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rfc:rfc3441

Network Working Group R. Kumar Request for Comments: 3441 Cisco Systems Category: Informational January 2003

             Asynchronous Transfer Mode (ATM) Package
           for the Media Gateway Control Protocol (MGCP)

Status of this Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

 This document describes an Asynchronous Transfer Mode (ATM) package
 for the Media Gateway Control Protocol (MGCP).  This package includes
 new Local Connection Options, ATM-specific events and signals, and
 ATM connection parameters.  Also included is a description of codec
 and profile negotiation.  It extends the MGCP that is currently being
 deployed in a number of products.  Implementers should be aware of
 developments in the IETF Megaco Working Group and ITU SG16, which are
 currently working on a potential successor to this protocol.

Table of Contents

 1.0  Conventions Used in this Document..............................2
 2.0  Introduction...................................................2
 3.0  Local Connection Options.......................................3
   3.1 ATM Bearer Connection.........................................4
   3.2 ATM Adaptation Layer (AAL)....................................8
   3.3 Service Layer................................................15
   3.4 ATM Bearer Traffic Management................................19
   3.5 AAL Dimensioning.............................................27
 4.0 Signals and Events.............................................30
 5.0 Connection Parameters..........................................35
 6.0 Negotiation of Profiles and Codecs in ATM Applications.........37
   6.1  Consistency of Parameters...................................37
   6.2  Codec/Profile Negotiation in ATM Networks...................38
 7.0  Security Considerations.......................................45
 8.0  IANA Considerations...........................................45
 9.0  References....................................................45
 10.0 Acronyms......................................................48

Kumar Informational [Page 1] RFC 3441 ATM MGCP Package January 2003

 11.0 Acknowledgements..............................................49
 12.0 Author's Address..............................................49
 13.0 Full Copyright Statement......................................50

1.0 Conventions Used in this Document

 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
 document are to be interpreted as described in BCP 14, RFC 2119.
 MGCP identifiers are case-insensitive.  This includes package names,
 event names, local connection options and other elements of the MGCP
 header.

2.0 Introduction

 The Media Gateway Control Protocol or MGCP [36] is used to control
 voice media gateways from external call control elements.  Even
 though the bearer network might be IP, ATM, TDM or a mix of these,
 MGCP is transported over IP.  Packages such as the MGCP CAS packages
 [38] are modular sets of parameters such as connection options,
 signal, event and statistics definitions that can be used to extend
 it into specific contexts.  A related,  IP-based mechanism for the
 description of ATM connections [18] has been generated by the IETF
 MMUSIC group.  Due to the IP-centric nature of all aspects of the
 MGCP device control protocol, and for consistency with other MGCP
 package definitions, it is desirable to publish the MGCP ATM package
 in an IETF document.
 MGCP [36] allows the auditing of endpoints for package versions
 supported.  The package version for the MGCP ATM package, as
 specified in this document, is 0.  Even if the ATM package is the
 default package for some endpoints, the package prefix "atm" shall
 not be omitted in local connection option names, event names, signal
 names etc.  If the ATM package is the default package for an
 endpoint, it will be listed as the first package in the audit
 response list.  It is not necessary for the MGCP ATM package to be
 the default package for ATM to be supported on an endpoint.
 The ATM package in this document consists of Local Connection Options
 (Section 3.0), Events and Signals (Section 4.0) and ATM Statistics
 Parameters (Section 5.0).  Section 6.1 has guidelines for consistency
 in the use of Local Connection Options.  Section 6.2 describes codec
 and profile negotiation.  Section 7.0 addresses security
 considerations.

Kumar Informational [Page 2] RFC 3441 ATM MGCP Package January 2003

 In the ATM networks addressed in this document, services are carried
 directly over ATM without an intervening IP layer.  The Local
 Connection Options, Events, Signals and Statistics Parameters
 described in this section are not needed for VoIP calls which can be
 carried, in whole or in part, over an ATM network.  In that case, the
 constructs defined elsewhere for IP are sufficient.
 The ATM local connection option names, event names and signal names
 MUST always have an "atm" package prefix.  Backward compatibility
 with older implementations that use X-atm as the package name is
 desirable.
 MGCP grammar [36] must be followed with regard to the use of white
 spaces.  The examples in this document attempt to follow MGCP grammar
 in this and all other respects.

3.0 Local Connection Options

 The Local Connection Options (LCOs) defined in this section are
 specific to ATM applications.  Like other LCOs, these can be used in
 commands to create connections, modify connections and audit
 connections.  However, unless noted otherwise below, they are not to
 be returned when an endpoint is audited for capabilities.
 ATM Local Connection Options are divided into the following
 categories: ATM bearer connection, ATM adaptation layer, service
 layer, ATM bearer traffic management and AAL dimensioning.
 When parameter values are represented in decimal format, leading
 zeros are omitted.

Kumar Informational [Page 3] RFC 3441 ATM MGCP Package January 2003

3.1 ATM Bearer Connection

 These local connection options are used to parameterize ATM bearer
 connections.
 TABLE 1: Local Connection Options for ATM Bearers
 +---------+---------------+---------------------------------------+
 |  LCO    |    Meaning    |           Values                      |
 +---------+---------------+---------------------------------------+
 |   ct    | Connection    |AAL1, AAL1_SDT, AAL1_UDT, AAL2, AAL3/4,|
 |         | Type          |AAL5, USER_DEFINED_AAL                 |
 +---------+---------------+---------------------------------------+
 |   vc    |VC/Bearer type | PVC, SVC, CID                         |
 +---------+---------------+---------------------------------------+
 |   se    | Enable path   | on, off                               |
 |         | set-up        |                                       |
 +---------+---------------+---------------------------------------+
 |   ci    | Connection    | See below                             |
 |         | Element       |                                       |
 |         | Identifier    |                                       |
 +---------+---------------+---------------------------------------+
 Connection type (ct): This parameter describes the ATM adaptation
 layer.  The values that can be assigned to it are: AAL1, AAL1_SDT,
 AAL1_UDT, AAL2, AAL3/4, AAL5 and USER_DEFINED_AAL.  The user defined
 adaptation layer is per amendment 2 of ITU-T Q.2931.
 Type of Bearer/VC (vc): This indicates whether a PVC, CID or an SVC
 is to be used for an ATM connection.  Possible values are: PVC, SVC
 or CID.  Omitting this parameter will result in the use of a default,
 which could be embedded or provisioned.  The value "PVC" covers both
 classical PVCs and SPVCs.  The value "CID"  covers subchannels within
 AAL1 [35] and AAL2 [10] virtual circuits.  A value of "SVC" for
 atm/vc does not necessarily imply that the addressed media gateway
 should initiate signaling for bearer set-up, since this might be done
 by another node such as the far-end media gateway.
 Enable path set-up (se): This local connection option is used to
 explicitly enable or disable the use of bearer signaling for path
 set-up.  Permitted values of this local connection option are  "on"
 and "off".  Examples of bearer signaling are SVC signaling, ITU
 Q.2630.1 signaling and combinations thereof.  Examples of such
 combinations are the set-up of an AAL2 SVC and the assignment of a
 CID within it or the set-up of a concatenation of an AAL2 single-CID
 SVC and a CID channel within a multiplexed AAL2 VC.  This parameter
 can be used with both the backward and forward bearer connection

Kumar Informational [Page 4] RFC 3441 ATM MGCP Package January 2003

 set-up methods.  In the former case, the call-terminating gateway
 sets up the bearer connection.  In the latter case, the call-
 originating gateway sets up the bearer connection.
 This option may or may not be used in conjunction with atm/sc event
 notification.  When this option and the atm/sc event notification are
 omitted, creating and modifying connection commands, the call agent
 is deferring any relevant decision to set up an ATM or AAL2
 connection to the media gateways.  In the absence of this parameter,
 a media gateway's autonomous decision to set up an ATM or AAL2 path
 via bearer signaling depends on default/provisioned behaviors, such
 as the applicability and nature (backward/forward) of a bearer
 connection set-up model, the network type ('nt'), connection type
 ('atm/ct') and bearer type/VC ('atm/vc') local connection options,
 and the media gateway's awareness of whether it is the originating
 gateway or terminating gateway in a call.  This awareness may be
 based on the presence or absence of an SDP remote connection
 descriptor in the initial create connection command.
 Connection Element Identifier (ci): This indicates the Virtual
 Circuit or CID to be used for the bearer connection.  It is used when
 the call agent manages VC and/or CID resources in the bearer network.
 The ci parameter can be in one of the following formats:
  • VCCI-<vcci>
  • VCCI-<vcci>/CID-<cid>
  • <ATMaddressType>-<ATMaddress>/VCCI-<vcci>
  • <ATMaddress>/VCCI-<vcci>
  • <ATMaddressType>-<ATMaddress>/VCCI-<vcci>/CID-<cid>
  • <ATMaddress>/VCCI-<vcci>/CID-<cid>
  • BCG-<bcg>/VCCI-<vcci>
  • BCG-<bcg>/VCCI-<vcci>/CID-<cid>
  • BCG-<bcg>/VPI-<vpi>/VCI-<vci>
  • BCG-<bcg>/VPI-<vpi>/VCI-<vci>/CID-<cid>
  • PORT-<portId>/VPI-<vpi>/VCI-<vci>
  • PORT-<portId>/VPI-<vpi>/VCI-<vci>/CID-<cid>
  • VPCI-<vpci>/VCI-<vci>
  • VPCI-<vpci>/VCI-<vci>/CID-<cid>
  • <ATMaddressType>-<ATMaddress>/VPCI-<vpci>/VCI-<vci>
  • <ATMaddress>/VPCI-<vpci>/VCI-<vci>
  • <ATMaddressType>-<ATMaddress>/VPCI-<vpci>/VCI-<vci>/CID-<cid>
  • <ATMaddress>/VPCI-<vpci>/VCI-<vci>/CID-<cid>

Kumar Informational [Page 5] RFC 3441 ATM MGCP Package January 2003

 The subparameters of the ci parameter are defined as follows:
 |--------------|-----------------------|----------------------------|
 | Subparameter |    Meaning            |   Representation           |
 |--------------|-----------------------|----------------------------|
 |     vcci     | VC connection Id      | Decimal Integer            |
 |              |                       | (16-bit equivalent)        |
 |--------------|-----------------------|----------------------------|
 |     cid      | Channel Id            | Decimal Integer            |
 |              |                       | (8-bit equivalent)         |
 |--------------|-----------------------|----------------------------|
 |ATMaddressType| ATM address type      | "NSAP", "E164", "GWID",    |
 |              |                       | "ALIAS"                    |
 |--------------|-----------------------|----------------------------|
 | ATMaddress   | ATM address           | 40 hex digits   ("NSAP")   |
 |              |                       | upto 15 digits ("EI64")    |
 |              |                       | upto 32  chars ("GWID")    |
 |              |                       | upto 32  chars ("ALIAS")   |
 |--------------|-----------------------|----------------------------|
 |    bcg       |Bearer Connection Group| Decimal Integer            |
 |              |                       | (8-bit equivalent)         |
 |--------------|-----------------------|----------------------------|
 |    vpi       |    Virtual Path Id    | Decimal Integer            |
 |              |                       | (8 or 12-bit equivalent)   |
 |--------------|-----------------------|----------------------------|
 |    vci       |    Virtual Channel Id | Decimal Integer            |
 |              |                       | (16-bit equivalent)        |
 |--------------|-----------------------|----------------------------|
 |    portID    |    Port Id            | Decimal Integer            |
 |              |                       | (32-bit equivalent)        |
 |--------------|-----------------------|----------------------------|
 |    vpci      |    VP connection ID   | Decimal Integer            |
 |              |                       | (16-bit equivalent)        |
 |--------------|-----------------------|----------------------------|
 The CID, or Channel ID, can refer to AAL1 as well as AAL2
 applications.  In AAL1 applications based on [35], it refers to the
 octet position, starting from one, within an n x 64 SDT frame.
 The VPCI is a 16 bit field defined in Section 4.5.16 of ITU Q.2931.
 The VPCI is similar to the VPI, except for its width and the fact
 that it retains its value across VP crossconnects.
 The VCCI is a 16 bit field defined in ITU Recommendation Q.2941.2
 [14].  The VCCI is similar to the VCI, except for the fact that it
 retains its value across VC crossconnects.

Kumar Informational [Page 6] RFC 3441 ATM MGCP Package January 2003

 In general, <vpci> and <vcci> values are unique between a pair of
 nodes.  When they are unique between a pair of nodes, but not unique
 within a network, they need to be qualified at any node, by the ATM
 address of the remote node.  These parameters can be pre-provisioned
 or signaled via SVC signaling messages.  When VPCI and VCCI values
 are pre-provisioned, administrations have the option of provisioning
 them uniquely in a network.  In this case, the ATM address of the far
 end is not needed to qualify these parameters.
 The <portId> parameter is used to identify the physical trunk port on
 an ATM module.  It can be represented as a decimal or hex number of
 up to 32 digits.
 In some applications, it is meaningful to bundle a set of connections
 between a pair of ATM nodes into a bearer connection group.  The
 <bcg> subparameter is an eight bit field that allows the bundling of
 up to 255 VPCs or VCCs.
 In some applications, it is necessary to wildcard some elements of
 the ci local connection option.  The "$" wildcard character can be
 substituted for some of the terms of this parameter.  While
 wildcarding, the constant strings that qualify the terms in the ci
 parameter are retained.  The concatenation <ATMaddressType>-
 <ATMaddress> can be wildcarded in the following ways:
  • The entire concatenation, <ATMaddressType>-<ATMaddress>, is

replaced with a "$".

  • <ATMaddress> is replaced with a "$", but <ATMaddressType> is

not.

 Examples of wildcarding the ci parameter in the AAL1 and AAL5
 contexts are: VCCI-$, BCG-100/VPI-20/VCI-$.
 Examples of wildcarding the ci parameter in the AAL2 context are:
 VCCI- 40/CID-$, BCG-100/VPI-20/VCI-120/CID-$.
 If the addressType is NSAP, the address is expressed in the standard
 dotted hex form.  This is a string of 40 hex digits, with dots after
 the 2nd, 6th, 10th, 14th, 18th, 22nd, 26th, 30th, 34th and 38th
 digits.  The "0x" prefix is not used, since this is always
 represented in hex.  The last octet of the NSAP address is the
 'selector' field that is available for non-standard use.  For
 example:
L: atm/ci:NSAP-47.0091.8100.0000.0060.3e64.fd01.0060.3e64.fd01.00/
          VCCI-65

Kumar Informational [Page 7] RFC 3441 ATM MGCP Package January 2003

 If the ATMaddressType is E164, the ATMaddress is expressed as a
 decimal number with up to 15 digits.  For example:
    L: atm/ci:E164-9738294382/VCCI-100
 The E.164 numbers used can be in the International Format E.164 or
 conform to a private numbering plan.
 If the ATMaddressType is GWID, it means that the address is a Gateway
 Identifier or Node Alias.  This may or may not be globally unique.
 In this format, the ATMaddress is expressed as an alphanumeric string
 ("A"-"Z", "a"-"z", "0" - "9",".","-","_").  For example:
     L: atm/ci:GWID-officeABCmgx101vism12
 The keyword "ALIAS" can be substituted for "GWID".  For example:
     L: atm/ci:ALIAS-officeABCmgx101vism12
 An example of a GWID (ALIAS) is the CLLI code used for telecom
 equipment.  For all practical purposes, it should be adequate for the
 GWID (ALIAS) to be a variable length string with a maximum size of 32
 characters.
 When an endpoint supporting the ATM package is audited for
 capabilities, the following local connection options from Section 3.1
 shall be returned: connection type (atm/ct) and VC/bearer type
 (atm/vc).  If more than one value is supported, these shall be
 expressed as a list of semicolon-separated values.  Although this is
 not very useful, it is permissible for these values to have
 overlapping semantics (e.g., AAL1 and AAL1_SDT).  An example of
 returning, in audit response, the local connection options defined in
 Section 3.1 is:
    A: atm/ct:AAL1_SDT;AAL2, atm/vc:PVC;CID

3.2 ATM Adaptation Layer (AAL)

 These local connection options are used to parameterize the ATM
 adaptation layer (AAL).  These are further classified as: generic AAL
 connection options, AAL1-related connection options and AAL2-related
 connection options.  Currently, there are no local connection options
 defined in this category that pertain to AAL5.

Kumar Informational [Page 8] RFC 3441 ATM MGCP Package January 2003

 TABLE 2: Generic Local Connection Options for the AAL
 +---------+---------------+---------------------------------------+
 |  LCO    |    Meaning    |           Values                      |
 +---------+---------------+---------------------------------------+
 | aalApp  | Application   |itu_h323c,af83,AAL5_SSCOP,             |
 |         |               |itu_i3661_unassured, itu_i3661_assured |
 |         |               |itu_i3662, itu_i3651, itu_i3652,       |
 |         |               |itu_i3653, itu_i3654,                  |
 |         |               |FRF5, FRF8, FRF11,itu_h2221            |
 +---------+---------------+---------------------------------------+
 |   sbc   | Subchannel    | 1...24 for T1-based applications      |
 |         | Count         | 1...31 for E1-based applications      |
 +---------+---------------+---------------------------------------+
 AAL application (aalApp): This connection option specifies the
 controlling standard for an application layer above the ATM
 adaptation layer.  Other strings can be defined.  If used, these need
 to be prefixed with an "X-".
    "itu_h323c"             Annex C of H.323 which specifies direct
                            RTP on AAL5 [12].
    "af83"                  af-vtoa-0083.001, which specifies
                            variable size AAL5 PDUs with PCM voice
                            and a null SSCS [13].
    "AAL5_SSCOP"            SSCOP as defined in ITU Q.2110 [14]
                            running over an AAL5 CPS [27].
                            No information is provided regarding
                            any layers above SSCOP such as Service
                            Specific Coordination Function  (SSCF)
                            layers.
    "itu_i3661_unassured"   SSCS with unassured transmission,
                            per ITU I.366.1 [11].
    "itu_i3661_assured"     SSCS with assured transmission,
                            per ITU I.366.1 [11].  This uses SSCOP
                            [14].
    "itu_i3662"             SSCS per ITU I.366.2 [2].
    "itu_i3651"             Frame relay SSCS per ITU I.365.1 [15].
    "itu_i3652"             Service-specific coordination function,
                            as defined in ITU I.365.2, for Connection
                            Oriented Network Service (SSCF-CONS)
                            [16].  This uses SSCOP [14].

Kumar Informational [Page 9] RFC 3441 ATM MGCP Package January 2003

    "itu_i3653"             Service-specific coordination function,
                            as defined in ITU I.365.3, for Connection
                            Oriented Transport Service (SSCF-COTS)
                            [17].  This uses SSCOP [14].
    "itu_i3654"             Service-specific coordination function,
                            as defined in ITU I.365.4 [28].
    "FRF5"                  Use of the FRF.5 frame relay standard
                            [23], which references ITU I.365.1 [15].
    "FRF8"                  Use of the FRF.8 frame relay standard
                            [24].  This implies a null SSCS and the
                            mapping of the frame relay header
                            into the ATM header.
    "FRF11"                 Use of the FRF.11 frame relay standard
                            [25].
    "itu_h2221"             Use of the ITU standard H.222.1 for
                            audiovisual communication over AAL5
                            [22].
 Subchannel count (sbc): This parameter indicates the number of DS0s
 in an n x 64 connection.  Such connections use an ATM adaptation
 layer 1 (ATM forum af-vtoa-78) or 2 (ITU I.366.2).  For T1-based
 applications, it can take on integral values in the inclusive range
 [1...24].  For E1-based applications, it can take on integral values
 in the inclusive range [1...31].  When this parameter is omitted, the
 subchannel count must be known by other means.
 TABLE 3: Local Connection Options for AAL Type 1
 +---------+---------------+---------------------------------------+
 |  LCO    |    Meaning    |           Values                      |
 +---------+---------------+---------------------------------------+
 |   pf    | Partial fill  | 1...48                                |
 |         |               |                                       |
 +---------+---------------+---------------------------------------+
 |   crt   | Clock Recovery|  NULL, SRTS, ADAPTIVE                 |
 |         | Type          |                                       |
 +---------+---------------+---------------------------------------+
 |   fe    | FEC enable    | NULL, DELAY_SENSITIVE,LOSS_SENSITIVE  |
 +---------+---------------+---------------------------------------+

Kumar Informational [Page 10] RFC 3441 ATM MGCP Package January 2003

 Partial Fill Count (pf): When present, the 'pf' parameter is used to
 indicate the fill level of cells.  When this local connection option
 is absent, then other means (such as provisionable defaults) are used
 to determine the presence and level of partial fill.
 This parameter indicates the number of non-pad payload octets, not
 including any AAL SAR or convergence sublayer octets.  For example,
 in some AAL1 applications that use partially filled cells with
 padding at the end, this attribute indicates the number of leading
 payload octets not including any AAL overhead.
 In general, permitted values of the pf parameter are integers in the
 range 1 - 48 inclusive.  However, this upper bound is different for
 different adaptations since the AAL overhead, if any, is different.
 If a specified partial fill (e.g. 47) is greater than or equal to the
 maximum fill (in this example, 46 for AAL1 P-cells), then complete
 fill (46 in this example) is used.  Using a 'partial' fill of 48
 effectively disables partial fill. Values below or above the
 permissible range of 1-48 MUST be rejected with an error code of 532
 {Unsupported value(s) in LocalConnectionOptions}.
 In the AAL1 context, this parameter applies uniformly to both P and
 non-P cells.  In AAL1 applications that do not distinguish between P
 and non-P cells, a value of 47 indicates complete fill (i.e., the
 absence of partial fill).  In AAL1 applications that distinguish
 between P and non-P cells, a value of 46 indicates no padding in
 P-cells and a padding of one in non-P cells.
 If partial fill is enabled (i.e., there is padding in at least some
 cells), then AAL1 structures must not be split across cell
 boundaries.  These shall fit in any cell.  Hence, their size shall be
 less than or equal to the partial fill size.  Further, the partial
 fill size is preferably an integer multiple of the structure size.
 If it is not, then the partial fill size stated in the local
 connection options shall be truncated to an integer multiple of the
 structure size (e.g., a partial fill size of 40 is truncated to 36 to
 support six 6 x 64 channels).
 Clock recovery type (crt): This is used in AAL1 UDT (unstructured
 data transfer) applications only.  It can be assigned the values:
 "NULL", "SRTS", or "ADAPTIVE".  A value of "NULL" is equivalent to
 omitting this parameter and implies that the stream (T1 or E1)
 encapsulated in ATM is either synchronous to the ATM network or is
 re-timed, before AAL1 encapsulation, via slip buffers.  The default
 value used in the absence of this LCO can be hardcoded or
 provisioned.

Kumar Informational [Page 11] RFC 3441 ATM MGCP Package January 2003

 Forward Error Correction Enable (fe): This indicates whether FEC, as
 defined in ITU I.363.1 [1], is enabled or not.  Possible values are:
 "NULL", "DELAY_SENSITIVE" and "LOSS_SENSITIVE".  FEC can be enabled
 differently for delay-sensitive and loss-sensitive connections.  A
 "NULL" value implies disabling FEC for an AAL1 connection.
 TABLE 4: Local Connection Options for AAL Type 2
 +---------+---------------+---------------------------------------+
 |  LCO    |    Meaning    |           Values                      |
 +---------+---------------+---------------------------------------+
 |   pfl   | Profile List  |  See below                            |
 |         |               |                                       |
 +---------+---------------+---------------------------------------+
 | smplCPS | Simplified CPS|  on, off                              |
 |         | [21]          |                                       |
 +---------+---------------+---------------------------------------+
 |   tmcu  | Combined use  | Integer microseconds                  |
 |         | timer         | (32-bit equivalent)                   |
 +---------+---------------+---------------------------------------+
 |  aalsap |Service access | AUDIO, MULTIRATE                      |
 |         |point          |                                       |
 +---------+---------------+---------------------------------------+
 |   cktmd | Circuit mode  | on, off                               |
 |         |               |                                       |
 +---------+---------------+---------------------------------------+
 |   frmd  | Frame mode    | on,off                                |
 |         | enable        |                                       |
 +---------+---------------+---------------------------------------+
 | genpcm  | Generic PCM   | PCMA, PCMU                            |
 |         | setting       |                                       |
 +---------+---------------+---------------------------------------+
 |  ted    | Transmission  | on,off                                |
 |         |error detection|                                       |
 +---------+---------------+---------------------------------------+
 |rastimer | SSSAR         |                                       |
 |         | reassembly    | Integer microseconds                  |
 |         | timer         | (32-bit equivalent)                   |
 +---------+---------------+---------------------------------------+
 Profile List (pfl): This is a list of profiles.  Profile types are
 followed by profile numbers for each type.  The ordering of profiles
 can imply preference, with the most preferred profile first.  There
 can be multiple instances of the same profile type in this list.
 Spaces are used as delimiters within this list.  Therefore, to comply
 with MGCP syntax [36], it is necessary to enclose this list in double
 quotes.

Kumar Informational [Page 12] RFC 3441 ATM MGCP Package January 2003

 The format of the pfl parameter is as follows:
 "<profileType#1><format list#1><profileType#2><format list#2> ...
 <profileType #M><format list#M>"
 where <format list#i> has the form <profile#i_1>...<profile#i_N>
 The <profileType> parameter indicates the type of profile.  It is
 expressed in the format AAL2/<profileClass> where <profileClass>
 identifies the source of the definition of the profile.
 The <profileClass> can be assigned a string value indicating the
 source of the subsequent profile numbers until the next <profileType>
 field.  The following rules apply to the contents of the
 <profileClass> field:
  1. <profileClass> = "ITU" indicates profiles defined by ITU.

Examples: profiles defined in the I.366.2 specification [2].

  1. <profileClass> = "ATMF" indicates profiles defined by ATM

forum. Examples: profiles defined in af-vtoa-0113 [3] or af-

       vmoa-0145.000 [21].
    -  <profileClass> = "custom"  indicates profiles defined by a
       corporation or a multi-vendor agreement.  Since there is no
       standard administration of this convention, care should be
       taken to preclude inconsistencies within the scope of a
       deployment.
    - <profileClass> = <corporateName>
       An equipment vendor or service provider can use its registered,
       globally unique corporate name (e.g., Cisco, Telcordia etc.) as
       a string value of the <profileClass>.  It is suggested that
       organizations maintain consistent definitions of the advertised
       AAL2 profiles that bear their corporate name.
    -  The <profileClass> can be based on IEEE Standard 802-1990,
       Section 5.1, which defines the globally unique, IEEE-
       administered, three-octet OUIs used in MAC addresses and
       protocol identifiers.  In this case, the <profileClass> field
       shall be assigned a string value of "IEEE:" concatenated with
       <oui> where <oui> is the hex representation of a three-octet
       field identical to the IEEE OUI.  Since this is always
       represented in hex, the "0x" prefix is not used.  Leading zeros
       may be omitted.  For example, "IEEE:00000C" and "IEEE:C" both
       refer to Cisco Systems, Inc.
 The <profile#> parameter is expressed as a decimal number in the
 range 1-255.

Kumar Informational [Page 13] RFC 3441 ATM MGCP Package January 2003

 An example of the use of the pfl parameter is:

L: atm/pfl:"AAL2/ITU 8 AAL2/ATMF 7 8 AAL2/custom 100 AAL2/cisco 200"

 The syntax for pfl can be represented compactly in the following ABNF
 (RFC2234) form:
   pfl  = "%x22" 1*(profileType (1*profile#))"%x22"
   profileType = "AAL2/" profileClass space
   profile# = 1-255 space ; decimal integer followed by space
   profileClass  =
           "ATMF"/"ITU"/"custom"/corporateName/("IEEE:" oui)
   corporateName =  1*ALPHA   ;one or more alphanumeric characters
   oui  = 1*6 HEXDIG; 1-6 hex digits per IEEE Standard 802-1990
   space = %d32
 Simplified CPS (smplCPS): This enables the AAL2 CPS simplification
 described in [21].  It can be assigned the following values: on, off.
 Under this simplification, each ATM cell contains exactly one AAL2
 packet.  If necessary, octets at the end of the cell are padded with
 zeros.
 AAL2 combined use timer (tmcu): This is defined in ITU I.363.2 [10].
 It is an integer number of microseconds, represented as the decimal
 equivalent of 32 bits.
 AAL service access point (aalsap): The service access point for AAL2
 is defined in ITU I.366.2 [2].  The aalsap local connection option
 can take on the following string values: AUDIO, MULTIRATE.
 Circuit mode (cktmd): This is used to enable circuit mode data [2].
 It can be assigned a value of "on" or "off".
 Frame mode (frmd): This is used to enable frame mode data [2].  It
 can be assigned a value of "on" or "off".
 Generic PCM setting (genpcm): This indicates whether generic PCM
 encoding in AAL2 profiles is A-law or Mu-law.  It can be assigned the
 string values of "PCMA" and "PCMU".
 Transmission error detection (ted): Transmission error detection is
 defined in ITU I.366.1 [11].  The ted local connection option can
 take on the following values: on, off.  This local connection option
 is useful in qualifying the aalApp local connection option, when the
 value of the latter is "itu_i3661_unassured".

Kumar Informational [Page 14] RFC 3441 ATM MGCP Package January 2003

 SSSAR reassembly timer (rastimer): This is defined in ITU I.366.1
 [11].  It is an integer number of microseconds, represented as the
 decimal equivalent of 32 bits.
 When an endpoint supporting the ATM package is audited for
 capabilities, the following local connection options from Section 3.2
 shall be returned: application (atm/aalApp).  Further, if one of the
 values atm/ct is "AAL2", the following additional local connection
 options shall be returned: profile list (atm/pfl), simplified CPS
 (atm/smplCPS), service access point (atm/aalsap), circuit mode
 enable(atm/cktmd), frame mode enable (atm/frmd) and generic PCM
 setting (atm/genpcm).  If more than one value is supported, these
 shall be expressed as a list of semicolon-separated values.  For
 atm/smplCPS, atm/cktmd and atm/frmd, an audit can return "on", "off"
 or "on;off" depending on whether the mode is mandatory, unsupported
 or optional for the endpoint.
 An example of returning, in audit response, the local connection
 options defined in Section 3.2 is:
 A: atm/aalApp:itu_i3662, atm/pfl:"AAL2/ATMF 7 8", smplCPS:on;off,
 aalsap:MULTIRATE, cktmd:off, frmd:off, genpcm:PCMU;PCMA

3.3 Service Layer

 TABLE 5: Local Connection Options for the Service Layer
 +--------------+---------------+----------------------------------+
 |  LCO         |    Meaning    |           Values                 |
 +--------------+---------------+----------------------------------+
 |  vsel        | Voice codec   | See below                        |
 |              | Selection     |                                  |
 +--------------+---------------+----------------------------------+
 |  dsel        | Data codec    | See below                        |
 |              | Selection     |                                  |
 +--------------+---------------+----------------------------------+
 |  fsel        | Fax codec     | See below                        |
 |              | Selection     |                                  |
 +--------------+---------------+----------------------------------+
 |  ccnf        | Codec         | Even number (4 - 32) hex digits  |
 |              | Configuration |                                  |
 +--------------+---------------+----------------------------------+
 |  usi         | ISUP User     | Two hex digits                   |
 |              | Information   |                                  |
 +--------------+---------------+----------------------------------+

Kumar Informational [Page 15] RFC 3441 ATM MGCP Package January 2003

 Voice codec selection (vsel): This is a prioritized list of one or
 more 3-tuples describing voice service.  Each vsel 3-tuple indicates
 a codec, an optional packet length and an optional packetization
 period.
 The vsel local connection option is structured as follows:
    "<encodingName #1> <packetLength #1><packetTime #1>
    <encodingName #2> <packetLength #2><packetTime #2>
       ...
    <encodingName #N> <packetLength #N><packetTime #N>"
 where the <encodingName> refers to a codec name such as PCMU, G726-
 32, G729 etc.  See [18] and [34] for a list of codecs with static
 payload types.  The <packetLength> is a decimal integer
 representation of the packet length in octets.  The <packetTime> is a
 decimal integer representation of the packetization interval in
 microseconds.
 Voiceband data codec selection (dsel): This is a prioritized list of
 one or more 3-tuples describing voiceband data passthrough service.
 Each dsel 3-tuple indicates a codec, an optional packet length and an
 optional packetization period.  Depending on the application, the
 dsel local connection option may or may not cover facsimile service.
 This is indicated via an <fxIncl> flag preceding the list of 3-
 tuples.  This flag indicates whether the dsel list explicitly
 addresses facsimile ("on" value) or not ("off" value).  This flag can
 also be set to "-", which is equivalent to setting it to "off".
 If <fxIncl> is "on", then it is rarely useful to also include an fsel
 option.  However, it is syntactically correct to do so as long as the
 dsel and fsel options include an identical set of 3-tuples, perhaps
 in a different order.
 If <fxIncl> is "off", then any fsel list may still be ignored if the
 media gateway does not provide separate treatment of voiceband data
 passthrough and fax.  Since, in this case, there is no distinct
 facsimile service from the media gateway's perspective, any fsel list
 does not apply.
 The dsel local connection option is structured as follows:
    "<fxIncl> <encodingName #1> <packetLength #1><packetTime #1>
             <encodingName #2> <packetLength #2><packetTime #2>
             ...
             <encodingName #N> <packetLength #N><packetTime #N>"

Kumar Informational [Page 16] RFC 3441 ATM MGCP Package January 2003

 where the <encodingName> refers to a codec name such as PCMU, G726-
 32, G729 etc.  The <packetLength> is a decimal integer representation
 of the packet length in octets.  The <packetTime> is a decimal
 integer representation of the packetization interval in microseconds.
 Facsimile codec selection (fsel): This is a prioritized list of one
 or more 3-tuples describing fax service.  Each fsel 3-tuple indicates
 a codec, an optional packet length and an optional packetization
 period.  If the dsel option includes facsimile, the fsel connection
 option should be consistent with it.  Each fsel 3-tuple indicates a
 codec, an optional packet length and an optional packetization
 period.  The fsel local connection option is structured as follows:
       "<encodingName #1> <packetLength #1><packetTime #1>
       <encodingName #2> <packetLength #2><packetTime #2>
       ...
       <encodingName #N> <packetLength #N><packetTime #N>"
 where the <encodingName> refers to a codec name such as PCMU, G726-
 32, G729 etc.  The <packetLength> is a decimal integer representation
 of the packet length in octets.  The <packetTime> is a decimal
 integer representation of the packetization interval in microseconds.
 Since spaces are used as delimiters within the vsel, dsel and fsel
 lists, it is necessary to enclose these lists in double quotes [36].
 The vsel, fsel and dsel parameters complement the rest of the local
 connection options and should be consistent with them.
 Examples of the use of these parameters are:
    L: atm/vsel:"G729 10 10000 G726-32 40 10000"
    L: atm/dsel:"off PCMA 10 10000 G726-32 40 10000"
    L: atm/fsel:"PCMU 40 5000 G726-32 20 5000"
    L: atm/vsel:"G729 10 10000 G726-32 40 10000"
    L: atm/dsel:"on  PCMA 10 10000 G726-32 40 10000"
 The <packetLength>and <packetTime> can be set to "-" when not needed.
 A <fxIncl> value of "-" is equivalent to setting it to "off".  For
 example:
    L: atm/vsel:"G729 - - G726-32 - -"
    L: atm/dsel:"- G729 - - G726-32 - -"
    L: atm/fsel:"G729-24 - -"

Kumar Informational [Page 17] RFC 3441 ATM MGCP Package January 2003

 The vsel, dsel and fsel local connection options can be used in the
 AAL1, AAL2 and AAL5 contexts.  The <packetLength> and <packetTime>
 are not meaningful in the AAL1 case and should be set to "-".  In the
 AAL2 case, these local connection options indicate the preferred use
 of some or all of the rows in a given profile table.  If multiple 3-
 tuples are present, they can indicate a preferentially ordered
 assignment of some rows in that profile to voice, voiceband data
 passthrough or facsimile service (e.g., row A preferred to row B
 etc).  If multiple profiles are specified in the pfl parameter
 (described in section 3.2), the profile qualified by these local
 connection options is the first profile in the list.
 Codec configuration (ccnf): This is used to convey the contents of
 the single codec information element (IE) defined in [30].  The
 contents of this IE are: a single-octet Organizational Identifier
 (OID) field, followed by a single-octet Codec Type field, followed by
 zero or more octets of a codec configuration bit-map.  The semantics
 of the codec configuration bit-map are specific to the
 organization[30, 31].  Since this bit-map is always represented in
 hex format, the "0x" prefix is omitted.  Leading zeros are not
 omitted.  For example:
    L: atm/ccnf:01080C
 indicates an Organizational Identifier of 0x01(the ITU-T).  Using
 [57], the second octet (0x08) indicates a codec type of G.726
 (ADPCM).  The last octet, 0x0C indicates that 16 kbps and 24 kbps
 rates are NOT supported, while the 32 kbps and 40 kbps rates ARE
 supported.
 ISUP User Information (usi): This is used to convey the contents of
 the 'User Information Layer 1 protocol' field within the bearer
 capability information element defined in Section 4.5.5 of [32], and
 reiterated as the user service information element (IE) in Section
 3.57 of [33].  The 'User Information Layer 1 protocol' field consists
 of the five least significant bits of Octet 5 of this information
 element.
 The usi LCO represented as a string of two hex digits.  The "0x"
 prefix is omitted since this value is always hexadecimal.  These hex
 digits are constructed from an octet with three leading '0' bits and
 the last five bits equal to the 'User Information Layer 1 protocol'
 field described above.  Digits to the left are more significant than
 digits to the right.  The resulting values of the usi local
 connection option are as follows:

Kumar Informational [Page 18] RFC 3441 ATM MGCP Package January 2003

    VALUE   MEANING
    0x01    CCITT standardized rate adaption V.110 and X.30
    0x02    Recommendation G.711 Mu-law
    0x03    Recommendation G.711 A-law
    0x04    Recommendation G.721 32 kbps ADPCM
            and Recommendation I.460
    0x05    Recommendations H.221 and H.242
    0x06    Recommendation  H.223 and H.245
    0x07    Non-ITU-T standardized rate adaption
    0x08    ITU-T standardized rate adaption V.120
    0x09    CCITT standardized rate adaption X.31 HDLC flag stuffing

3.4 ATM Bearer Traffic Management

 These local connection options are used to convey ATM traffic
 parameters.
 TABLE 6: Local Connection Options for ATM bearer traffic management
 +---------+---------------+---------------------------------------+
 | ATM LCO |    Meaning    |           Values                      |
 +---------+---------------+---------------------------------------+
 | atc     | ATM transfer  |CBR, nrt-VBR, rt-VBR, UBR, ABR, GFR,   |
 |         | capability or |DBR,SBR,ABT/IT,ABT/DT                  |
 |         | service       |                                       |
 |         | category      |                                       |
 +---------+---------------+---------------------------------------+
 | sbt     |atc subtype    | 1...5                                 |
 +---------+---------------+---------------------------------------+
 | qos     | QoS class     | 0...5                                 |
 +---------+---------------+---------------------------------------+
 | bcob    |Broadband      | 0...31                                |
 |         |Connection     |(Defined values listed below)          |
 |         |-Oriented      |                                       |
 |         |Bearer Class   |                                       |
 +---------+---------------+---------------------------------------+
 | eetim   |End-to-end     |on,off                                 |
 |         |timing required|                                       |
 +---------+---------------+---------------------------------------+
 | stc     |Susceptibility | 0...3                                 |
 |         |to clipping    |(Defined values listed below)          |
 +---------+---------------+---------------------------------------+
 | upcc    |User plane     |0...3                                  |
 |         |connection     |(Defined values listed below)          |
 |         |configuration  |                                       |
 +---------+---------------+---------------------------------------+

Kumar Informational [Page 19] RFC 3441 ATM MGCP Package January 2003

 +---------+---------------+---------------------------------------+
 | aqf     |ATM QoS        | List, see below                       |
 |         |parameters,    |                                       |
 |         |forward        |                                       |
 |         |direction      |                                       |
 +---------+---------------+---------------------------------------+
 | aqb     |ATM QoS        | List, see below                       |
 |         |parameters,    |                                       |
 |         |backward       |                                       |
 |         |direction      |                                       |
 +---------+---------------+---------------------------------------+
 | adf0+1  |ATM traffic    | List, see below                       |
 |         |descriptor,    |                                       |
 |         |forward        |                                       |
 |         |direction,     |                                       |
 |         |CLP-independent|                                       |
 +---------+---------------+---------------------------------------+
 | adf0    |ATM traffic    | List, see below                       |
 |         |descriptor,    |                                       |
 |         |forward        |                                       |
 |         |direction,     |                                       |
 |         |CLP=0          |                                       |
 +---------+---------------+---------------------------------------+
 | adb0+1  |ATM traffic    | List, see below                       |
 |         |descriptor,    |                                       |
 |         |backward       |                                       |
 |         |direction,     |                                       |
 |         |CLP-independent|                                       |
 +---------+---------------+---------------------------------------+
 | adb     |ATM traffic    | List, see below                       |
 |         |descriptor,    |                                       |
 |         |backward       |                                       |
 |         |direction,     |                                       |
 |         |CLP=0          |                                       |
 +---------+---------------+---------------------------------------+
 | abrf    |ABR parameters,| List, see below                       |
 |         |forward        |                                       |
 |         |direction      |                                       |
 +---------+---------------+---------------------------------------+
 | abrb    |ABR parameters,| List, see below                       |
 |         |backward       |                                       |
 |         |direction      |                                       |
 +---------+---------------+---------------------------------------+
 |abrSetup |ABR connection | List, see below                       |
 |         |set-up         |                                       |
 |         |parameters     |                                       |
 +---------+---------------+---------------------------------------+

Kumar Informational [Page 20] RFC 3441 ATM MGCP Package January 2003

 ATM transfer capability (atc): This parameter indicates the ATM
 Transfer Capability described in ITU I.371 [19], equivalent to the
 ATM Service Category described in the UNI 4.1 Traffic Management
 specification [8].  In applications conforming to ITU I.371, this
 parameter can be assigned the following values: DBR, SBR, ABT/IT,
 ABT/DT, ABR.  In applications conforming to the UNI 4.1 Traffic
 Management specification, this parameter can be assigned the
 following values: CBR, nrt-VBR, rt-VBR, UBR, ABR, GFR.
 Subtype (sbt): This qualifies the atc local connection option.  It
 can be assigned integer values of 1...5.  The following combinations
 of the atc and sbt local connection options are meaningful:

atc sbt Resulting transport

CBR/DBR 1 Voiceband signal transport (ITU G.711, G.722, I.363) CBR/DBR 2 Circuit transport (ITU I.363) CBR/DBR 4 High-quality audio signal transport (ITU I.363) CBR/DBR 5 Video signal transport (ITU I.363) nrt-VBR 1 nrt-VBR.1 nrt-VBR 2 nrt-VBR.2 nrt-VBR 3 nrt-VBR.3 rt-VBR 1 rt-VBR.1 rt-VBR 2 rt-VBR.2 rt-VBR 3 rt-VBR.3 UBR 1 UBR.1 UBR 2 UBR.2 GFR 1 GFR.1 GFR 2 GRR.2 SBR 1 SBR1 SBR 2 SBR2 SBR 3 SBR3

 Subtypes for the atc values of CBR or DBR are per [29].  Subtypes for
 the remaining atc values are per [8] and [19].

Kumar Informational [Page 21] RFC 3441 ATM MGCP Package January 2003

 QoS class (qos): This indicates the QoS class specified in ITU
 I.2965.1 [4].  It can take on the integer decimal values in the range
 0 - 5.  These values are mapped into QoS classes as follows:
  1. ———————————————————

| VALUE | MEANING |

  1. ———————————————————

| 0 | Default QoS |

  1. ———————————————————

| 1 | Stringent |

  1. ———————————————————

| 2 | Tolerant |

  1. ———————————————————

| 3 | Bi-level |

  1. ———————————————————

| 4 | Unbounded |

  1. ———————————————————

| 5 | Stringent bi-level |

  1. ———————————————————
 Broadband Connection-Oriented Bearer Class (bcob): The bcob local
 connection option indicates the Broadband Connection-Oriented Bearer
 Class specified in ITU Q.2961.2 [5].  It is represented as a decimal
 number in the range 0 - 31, or its hex equivalent (range 0x0 - 0x1F).
 The following values are currently defined:
  1. ———————————————————

| VALUE | MEANING |

  1. ———————————————————

| 1 | BCOB-A |

  1. ———————————————————

| 3 | BCOB-C |

  1. ———————————————————

| 5 | Frame relaying bearer service |

  1. ———————————————————

| 16 | BCOB-X |

  1. ———————————————————

| 24 | BCOB-VP (transparent VP service) |

  1. ———————————————————
 End-to-end timing (eetim): This indicates whether end-to-end timing
 is required (Table 4-8 of [29]).  It can be assigned a value of "on"
 or "off".

Kumar Informational [Page 22] RFC 3441 ATM MGCP Package January 2003

 Susceptibility to clipping (stc): The stc local connection option
 indicates susceptibility to clipping.  It is represented as a decimal
 number in the range 0 - 3, or its hex equivalent (range 0x0 - 0x3).
 All values except those listed below are reserved.
  1. ———————————————————

| VALUE | MEANING |

  1. ———————————————————

| 0 | Not susceptible to clipping |

  1. ———————————————————

| 1 | Susceptible to clipping |

  1. ———————————————————
 User plane connection configuration (upcc): The upcc local connection
 option is represented as a decimal number in the range 0 - 3, or its
 hex equivalent (range 0x0 - 0x3).  All values except those listed
 below are reserved.
  1. ———————————————————

| VALUE | MEANING |

  1. ———————————————————

| 0 | Point to point |

  1. ———————————————————

| 1 | Point to multipoint |

  1. ———————————————————
 ATM QoS parameters, forward direction (aqf) and backward direction
 (aqb): Here, forward is the direction away from the media gateway,
 backward is the direction towards the gateway.  If the directional
 convention used by bearer signaling at the gateway is different, then
 appropriate translations must be done by the media gateway.  These
 parameters have the following format:
    "<cdvType><acdv><ccdv><eetd><cmtd><aclr>"
 Since spaces are used in this list, it must be enclosed in double
 quotes for MGCP compliance [36].
 The <cdvType> parameter can take on the string values of "PP" and
 "2P".  These refer to the peak-to-peak and two-point CDV as defined
 in UNI 4.0 [6] and ITU Q.2965.2 [7] respectively.
 The CDV parameters, <acdv> and <ccdv>, refer to the acceptable and
 cumulative CDVs respectively.  These are expressed in units of
 microseconds and represented as the decimal or hex equivalent of 24-
 bit fields.  These use the cell loss ratio, <aclr>, as the "alpha"
 quantiles defined in the ATMF TM 4.1 specification [8] and in ITU
 I.356 [9].

Kumar Informational [Page 23] RFC 3441 ATM MGCP Package January 2003

 The transit delay parameters, <eetd> and <cmtd>, refer to the end-to-
 end and cumulative transit delays respectively in milliseconds.
 These are represented as the decimal equivalents of 16-bit fields.
 These parameters are defined in Q.2965.2 [7], UNI 4.0 [8] and Q.2931
 [29].
 The <aclr> parameter refers to forward and backward acceptable cell
 loss ratios.  This is the ratio between the number of cells lost and
 the number of cells transmitted.  It is expressed as the decimal or
 hex equivalent of an 8-bit field.  This field expresses an order of
 magnitude n, where n is an integer in the range 1-15.  The Cell Loss
 Ratio takes on the value 10 raised to the power of minus n.
 If any of these parameters is not specified, is inapplicable or is
 implied, then it is set to "-".
 Examples of the use of the aqf and aqb local connection options are:
    L: atm/aqf:"PP 8125 3455 32000 - 11"
    L: atm/aqb:"PP 4675 2155 18000 - 12"
 This implies a forward acceptable peak-to-peak CDV of 8.125 ms, a
 backward acceptable peak-to-peak CDV of 4.675 ms, forward cumulative
 peak-to-peak CDV of 3.455 ms, a backward cumulative peak-to-peak CDV
 of 2.155 ms, a forward end-to-end transit delay of 32 ms, a backward
 end-to-end transit delay of 18 ms, an unspecified forward cumulative
 transit delay, an unspecified backward cumulative transit delay, a
 forward cell loss ratio of 10 raised to minus 11 and a backward cell
 loss ratio of 10 to the minus 12.
 ATM traffic descriptors, forward direction CLP=0+1 (adf0+1), backward
 direction CLP=0+1 (adb0+1), forward direction CLP=0 (adf0), backward
 direction CLP=0 (adb0): Here, forward is the direction away from the
 media gateway, backward is the direction towards the gateway.  If the
 directional convention used by bearer signaling at the gateway is
 different, then appropriate translations must be done by the media
 gateway.  The adf0+1, adb0+1, adf0 and adb0 local connection options
 have the following format:
    "<pcr><scr><mbs><cdvt><mcr><mfs><fd><te>"
 Since spaces are used in these lists, they must be enclosed in double
 quotes for MGCP compliance [36].
 These parameters are defined per the ATMF TM 4.1 specification [8].
 Each of these parameters can be set to "-" if the intent is to not
 specify it via MGCP.  These definitions are listed briefly in Table 7
 below.

Kumar Informational [Page 24] RFC 3441 ATM MGCP Package January 2003

 TABLE 7: ATM Traffic Descriptor Parameters
 PARAMETER        MEANING                            UNITS
   pcr            Peak Cell Rate                     Cells per second
   scr            Sustained Cell Rate                Cells per second
   mbs            Maximum Burst Size                 Cells
   cdvt           Cell Delay Variation Tolerance     Microseconds
   mcr            Minimum Cell Rate                  Cells per second
   mfs            Maximum Frame Size                 Cells
   fd             Frame Discard Allowed              on/off
   te             CLP tagging enabled                on/off
 The pcr, scr, cdvt and mbs can be represented as the decimal
 equivalents of 24-bit fields.  The mbs and mfs can be represented as
 the decimal equivalents of 16-bit fields.
 Examples of these local connection options are:
    L: atm/adf0+1:"200   100  20   - - - on  -",
       atm/adf0:"200   80   15   - - - -  off",
       atm/adb0+1:"200   100  20   - - - on -",
       atm/adb0:"200   80   15   - - - -  off"
 This implies a forward and backward PCR of 200 cells per second for
 all cells regardless of CLP, forward and backward PCR of 200 cells
 per second for cells with CLP=0, a forward and backward SCR of 100
 cells per second for all cells regardless of CLP, a forward and
 backward SCR of 80 cells per second for cells with CLP=0, a forward
 and backward MBS of 20 cells for all cells regardless of CLP, a
 forward and backward MBS of 15 cells for cells with CLP=0, an
 unspecified CDVT which can be known by other means, and an MCR and
 MFS which are unspecified because they are inapplicable.  Frame
 discard is enabled in both the forward and backward directions.
 Tagging is not enabled in either direction.
 ABR parameters, forward direction (abrf) and backward direction
 (abrb): Here, forward is the direction away from the media gateway,
 backward is the direction towards the gateway.  If the convention
 used by bearer signaling at the gateway is different, then
 appropriate translations must be done by the media gateway.  The abrf
 and abrb local connection options have the following format:
    "<nrm><trm><cdf><adtf>"
 Since spaces are used in these lists, they must be enclosed in double
 quotes for MGCP compliance [36].

Kumar Informational [Page 25] RFC 3441 ATM MGCP Package January 2003

 These ABR parameters are defined per [6] and [8].  Their definition
 is summarized in Table 8 below.  In MGCP, these are represented as
 the decimal equivalent of the binary fields mentioned below.  If any
 of these parameters is meant to be left unspecified, it is set to "-
 ".

TABLE 8: ABR Parameters +———–+———————————+———————–+

PARAMETER MEANING FIELD SIZE

+———–+———————————+———————–+

NRM Maximum number of cells per 3 bits
forward Resource Management cell

+———–+———————————+———————–+

TRM Maximum time between 3 bits
forward Resource Management cells

+———–+———————————+———————–+

CDF Cutoff Decrease Factor 3 bits

+———–+———————————+———————–+

ADTF Allowed Cell Rate Decrease 10 bits
Time Factor

+———–+———————————+———————–+

 ABR set-up parameters (abrSetup): This local connection option is
 used to indicate the ABR parameters needed during call/connection
 establishment (Section 10.1.2.2 of the UNI 4.0 signaling
 specification [6]).  The abrSetup local connection option has the
 following format:
    "<ficr><bicr><ftbe><btbe><crmrtt><frif><brif><frdf><brdf>"
 Since spaces are used in this list, it must be enclosed in double
 quotes for MGCP compliance [36].
 These parameters are defined per [6].  Their definitions are listed
 briefly in Table 9 below.  In these definitions, forward is the
 direction away from the media gateway, backward is the direction
 towards the gateway.  If the convention used by bearer signaling at
 the gateway is different, then appropriate translations must be done
 by the media gateway.  If any of these parameters is meant to be left
 unspecified, it is set to "-".

Kumar Informational [Page 26] RFC 3441 ATM MGCP Package January 2003

TABLE 9: ABR Set-up Parameters +———–+———————————-+———————+

PARAMETER MEANING REPRESENTATION

+———–+———————————-+———————+

<ficr> Forward Initial Cell Rate Decimal equivalent
(Cells per second) of 24-bit field

+———–+———————————-+———————+

<bicr> Backward Initial Cell Rate Decimal equivalent
(Cells per second) of 24-bit field

+———–+———————————-+———————+

<ftbe> Forward transient buffer Decimal equivalent
exposure (Cells) of 24-bit field

+———–+———————————-+———————+

<btbe> Backward transient buffer Decimal equivalent
exposure (Cells) of 24-bit field

+———–+———————————-+———————+

<crmrtt> Cumulative RM round-trip time Decimal equivalent
(Microseconds) of 24-bit field

+———–+———————————-+———————+

<frif> Forward rate increase factor Decimal integer
(used to derive cell count) 0 -15

+———–+———————————-+———————+

<brif> Backward rate increase factor Decimal integer
(used to derive cell count) 0 -15

+———–+———————————-+———————+

<frdf> Forward rate decrease factor Decimal integer
(used to derive cell count) 0 -15

+———–+———————————-+———————+

<brdf> Backward rate decrease factor Decimal integer
(used to derive cell count) 0 -15

+———–+———————————-+———————+

3.5 AAL Dimensioning

 The Local Connection Options in Table 10 are used to dimension the
 operation of the AAL.  In these parameters, forward is the direction
 away from the media gateway.  Backward is the direction towards the
 media gateway.  These parameters are represented as decimal integers
 in the ranges listed in Table 10.
 TABLE 10: Local Connection Options used to dimension the AAL
 +---------+---------------+---------------------------------------+
 |  LCO    |    Meaning    | Values (Decimal Integer)              |
 +---------+---------------+---------------------------------------+
 |   str   | Structure     |  1...65,535                           |
 |         | Size          |                                       |
 +---------+---------------+---------------------------------------+

Kumar Informational [Page 27] RFC 3441 ATM MGCP Package January 2003

 +---------+---------------+---------------------------------------+
 | cbrRate | CBR rate      | Bit map per Table 4-6 of [29]         |
 +---------+---------------+---------------------------------------+
 |  fcpcs  | Forward       | AAL2: 45 or 64                        |
 |         | maximum CPCS  | AAL5: 1-65,535                        |
 |         | SDU size      |                                       |
 +---------+---------------+---------------------------------------+
 |  bcpcs  | Backward      | AAL2: 45 or 64                        |
 |         | maximum CPCS  | AAL5: 1-65,535                        |
 |         | SDU size      |                                       |
 +---------+---------------+---------------------------------------+
 |fSDUrate | Forward       | 24-bit equivalent                     |
 |         | maximum AAL2  |                                       |
 |         | CPS SDU rate  |                                       |
 +---------+---------------+---------------------------------------+
 |bSDUrate | Backward      | 24-bit equivalent                     |
 |         | maximum AAL2  |                                       |
 |         | CPS SDU rate  |                                       |
 +---------+---------------+---------------------------------------+
 | ffrm    |Forward maximum| 1-65,535                              |
 |         |frame block    |                                       |
 |         |size           |                                       |
 +---------+---------------+---------------------------------------+
 | bfrm    |Backward       | 1-65,535                              |
 |         |maximum frame  |                                       |
 |         |block size     |                                       |
 +---------+---------------+---------------------------------------+
 |fsssar   |Forward maximum| 1-65,568                              |
 |         |SSSAR-SDU      |                                       |
 |         |size           |                                       |
 +---------+---------------+---------------------------------------+
 |bsssar   |Backward       | 1-65,568                              |
 |         |maximum SSSAR  |                                       |
 |         |SDU size       |                                       |
 +---------+---------------+---------------------------------------+
 |fsscopsdu|Forward maximum| 1-65,528                              |
 |         |SSCOP-SDU      |                                       |
 |         |size           |                                       |
 +---------+---------------+---------------------------------------+
 |         |               |                                       |
 |bsscopsdu|Backward       | 1-65,528                              |
 |         |maximum SSCOP  |                                       |
 |         |SDU size       |                                       |
 +---------+---------------+---------------------------------------+
 |fsscopuu |Forward maximum| 1-65,524                              |
 |         |SSCOP-UU field |                                       |
 |         |size           |                                       |
 +---------+---------------+---------------------------------------+

Kumar Informational [Page 28] RFC 3441 ATM MGCP Package January 2003

 +---------+---------------+---------------------------------------+
 |bsscopuu |Backward       | 1-65,524                              |
 |         |maximum SSCOP  |                                       |
 |         |UU size        |                                       |
 +---------+---------------+---------------------------------------+
 Structured Data Transfer Block Size (str): This parameter is
 meaningful only when structured AAL1 is used.  It indicates the size
 (in octets) of the block used for structured data transfer.  If not
 included as a local connection option, the structure size is to be
 known by other means.  For instance, af-vtoa-78 [20] fixes the
 structure size for n x 64 service, with or without CAS.  The
 L: atm/str parameter is coded as the decimal equivalent of a 16-bit
 field [29].  The theoretical maximum value of this parameter is
 65,535, although most services use much less.
 CBR Rate (cbrRate): This is a hexadecimal representation of the bit
 map defined in Table 4-6 of ITU Q.2931 [29].  This is represented as
 exactly two hex digits.  For example:
    L: atm/cbrRate:04
 implies a CBR rate of 1.544 Mbps.
 Forward maximum CPCS-SDU size (fcpcs): This is the maximum size of
 the AAL2 or AA5 CPCS SDU in the forward direction.
 Backward maximum CPCS-SDU size (bcpcs): This is the maximum size of
 the AAL2 or AA5 CPCS SDU in the backward direction.
 Forward maximum AAL2 CPCS-SDU rate (fSDUrate): This is the maximum
 rate of the AAL2 CPCS-SDUs in the forward direction.
 Backward maximum AAL2 CPCS-SDU rate (bSDUrate): This is the maximum
 rate of the AAL2 CPCS-SDUs in the backward direction.
 The fSDUrate and bSDUrate local connection options can be used to
 rate-limit AAL2 CIDs, especially when used in the SSSAR [1] and frame
 mode [2] contexts.
 Forward maximum frame mode block size (ffrm): This is the maximum
 size, in the forward direction, of the AAL2 frame mode data unit
 (I.366.2) [2].
 Backward maximum frame mode block size (bfrm): This is the maximum
 size, in the backward direction, of the AAL2 frame mode data unit
 (I.366.2) [2].

Kumar Informational [Page 29] RFC 3441 ATM MGCP Package January 2003

 Forward maximum SSSAR-SDU size (fsssar): This is the maximum size, in
 the forward direction, of the AAL2-based SSSAR-SDU (I.366.1) [1].
 Backward maximum SSSAR-SDU size (bsssar): This is the maximum size,
 in the backward direction, of the AAL2-based SSSAR-SDU (I.366.1) [1].
 Forward maximum SSCOP-SDU size (fsscopsdu): This is the maximum size,
 in the forward direction, of the AAL2-based SSCOP-SDU (I.366.1) [1].
 Backward maximum SSCOP-SDU size (bsscopsdu): This is the maximum
 size, in the backward direction, of the AAL2-based SSCOP-SDU
 (I.366.1) [1].
 Forward maximum SSCOP-UU size (fsscopuu): This is the maximum size,
 in the forward direction, of the AAL2-based SSCOP-UU field(I.366.1)
 [1].
 Backward maximum SSCOP-UU size (bsscopuu): This is the maximum size,
 in the backward direction, of the AAL2-based SSCOP- UU field
 (I.366.1) [1].

4.0 Signals and Events

 Standard MGCP syntax and keywords [36] are used in Table 11 to define
 the events in this package.  Since these are all connection events,
 they cannot be requested for endpoints.  For consistency with MGCP
 [36], it is required that the suffix @<connection-id> NOT be omitted
 even if there is only one connection to an endpoint.  This suffix can
 also be wildcarded per MGCP rules.
 There are no auditable event-states associated with the ATM package.
 Set-up complete ("sc"):
 Within the RequestedEvents (R:) structure, "sc" is used to request
 notification of successful ATM or AAL2 connection set-up.  The ATM OR
 AAL2 bearer path is ready for subscriber payload carriage when this
 notification is sent.
 This could be the set-up of an SVC, the assignment of an AAL2 CID
 path and combinations thereof.  Examples of such combinations are the
 set-up of an AAL2 SVC and the assignment of a CID within it or the
 set-up of a concatenation of an AAL2 single-CID SVC and a CID channel
 within a multiplexed AAL2 VC.
 This event is included for backward compatibility.  It is preferred
 that the call agent and the media gateway rely on provisional
 acknowledgements in the case in which connection set-up has a long

Kumar Informational [Page 30] RFC 3441 ATM MGCP Package January 2003

 latency.  However, if this event is requested, the media gateway must
 issue notification of connection set-up via this event.  In this
 case, a provisional acknowledgement is not very useful, and full
 acknowledgement of the create connection or modify connection need
 not be deferred until connection set up.
 The designated trigger for an ATM OR AAL2 connection set-up is an
 "on" value of the L: atm/se local connection option provided with a
 create or modify connection command.  However, it is recognized that
 certain applications use the presence of an atm/sc event notification
 to initiate the set-up of an ATM or AAL2 connection.
 TABLE 11: Signals and Events in the ATM package
 |---------------|-----------------------|-----|------|--------------|
 |    SYMBOL     |  DEFINITION           | R   |   S  |   DURATION   |
 |---------------|-----------------------|-----|------|--------------|
 |      sc       |  Bearer path set-up   |  C  |      |              |
 |               |  complete             |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 |      sf       |  Bearer path set-up   |  C  |      |              |
 |               |  failed               |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 |      ec       |  Enable CAS via       |     |  oo  |              |
 |               |  type 3 packets       |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 |     etd       |  Enable DTMF tone     |     |  oo  |              |
 |               |  forwarding via       |     |      |              |
 |               |  packets              |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 |     etm       |  Enable MF tone       |     |  oo  |              |
 |               |  forwarding via       |     |      |              |
 |               |  packets              |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 |     etr1      |  Enable MF-R1 tone    |     |  oo  |              |
 |               |  forwarding via       |     |      |              |
 |               |  packets              |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 |     etr2      |  Enable MF-R2 tone    |     |  oo  |              |
 |               |  forwarding via       |     |      |              |
 |               |  packets              |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 | uc (string)   |  Used codec changed   |  C  |      |              |
 |               |  to codec named by    |     |      |              |
 |               |  the string           |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 | ptime (#)     |  Packetization period |  C  |      |              |
 |               |  changed to #         |     |      |              |
 |---------------|-----------------------|-----|------|--------------|

Kumar Informational [Page 31] RFC 3441 ATM MGCP Package January 2003

 |---------------|-----------------------|-----|------|--------------|
 | pftrans (#)   |  Profile element      |  C  |      |              |
 |               |  changed to  row #    |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 | cle  (#)      |  Cell Loss            |  C  |      |              |
 |               |  threshold (# )       |     |      |              |
 |               |  exceeded             |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 | pl   (#)      |  Packet Loss Threshold|  C  |      |              |
 |               |  exceeded (# )        |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 | qa            |  Quality Alert        |  C  |      |              |
 |               |                       |     |      |              |
 |---------------|-----------------------|-----|------|--------------|
 | of   (#)      |  Operation failure:   |  C  |      |              |
 |               |  Loss of connectivity |     |      |              |
 |               |  with reason code #   |     |      |              |
 -------------------------------------------------------------------
 Set-up failed ("sf"):
 Within the RequestedEvents (R:) structure, "sf" is used to request
 notification of a failed ATM OR AAL2 connection set-up.  The ATM OR
 AAL2 connection set-ups addressed by "sf" are the same as for the
 "sc" event.
 In some ATM OR AAL2 applications with SVC set-up or bearer-signalled
 AAL2 path assignment, the "sf" event might not be used.  In these
 cases, the following options are available:
  • the call agent receives a spontaneous delete from the media

gateway with an appropriate reason code (902).

  • the call agent receives the "of" event described below with the

optional reason code (902).

 Enable CAS via type 3 packets ("ec"):
 This signal indicates that the media gateway is to forward CAS
 signaling via type 3 packets on an AAL2 connection.  This does not
 preclude the call agent from requesting notification of CAS state
 changes.  On receiving this signal request, the gateway sustains a
 bidirectional type 3 CAS protocol over the AAL2 path.  This comes to
 an end when the request is cancelled through a subsequent
 NotificationRequest command or when the VoAAL2 connection is deleted.

Kumar Informational [Page 32] RFC 3441 ATM MGCP Package January 2003

 Enable DTMF tones via type 3 packets ("etd"):
 A gateway will ignore this signal request if it normally forwards and
 receives DTMF tones via type 3 packets.  This signal indicates that
 the media gateway is to forward and receive DTMF tones via type 3
 packets on an AAL2 connection.  This does not preclude the call agent
 from requesting notification of DTMF tones.
 Enable MF tones via type 3 packets ("etm"):
 A gateway will ignore this signal request if it normally forwards and
 receives MF tones via type 3 packets.  This signal indicates that the
 media gateway is to forward and receive MF tones via type 3 packets
 on an AAL2 connection.  This does not preclude the call agent from
 requesting notification of MF tones.  This signal request does not
 specify the MF tone type, which is known by other means.
 Enable R1 MF tones via type 3 packets ("etr1"):
 A gateway will ignore this signal request if it normally forwards and
 receives R1 MF tones via type 3 packets.  This signal indicates that
 the media gateway is to forward and receive R1 MF tones via type 3
 packets on an AAL2 connection.  This does not preclude the call agent
 from requesting notification of R1 MF tones.
 Enable R2 MF tones via type 3 packets ("etr2"):
 A gateway will ignore this signal request if it normally forwards and
 receives R2 MF tones via type 3 packets.  This signal indicates that
 the media gateway is to forward and receive R2 MF tones via type 3
 packets on an AAL2 connection.  This does not preclude the call agent
 from requesting notification of R2 MF tones.
 Used codec changed ("uc (string)"):
 If armed via an R:atm/uc, a media gateway signals a codec change
 through an O:atm/uc.  The alphanumeric string in parentheses is
 optional.  It is the encoding name of the codec to which the switch
 is made.  Although this event can be used with all ATM adaptations
 (AAL1, AAL2 and AAL5):
  • The pftrans event is more suited to AAL2 applications.
  • Codec switches do not generally occur mid-call in AAL1

applications.

Kumar Informational [Page 33] RFC 3441 ATM MGCP Package January 2003

 Packet time changed ("ptime(#)"):
 If armed via an R:atm/ptime, a media gateway signals a packetization
 period change through an O:atm/ptime.  The decimal number in
 parentheses is optional.  It is the new packetization period in
 milliseconds.  In AAL2 applications, the pftrans event can be used to
 cover packetization period changes (and codec changes).
 Profile element changed ("pftrans(#)"):
 If armed via an R:atm/pftrans, a media gateway signals a mid-call
 profile element change through an O:atm/ptime.  This event is used
 with AAL2 adaptation only.  A profile element is a row in a profile
 table.  Profile elements indicating silence should not trigger this
 event.  The decimal number in parentheses is optional.  It is the row
 number to which the switch is made.  Rows are counted downward,
 beginning from 1.
 Cell loss exceeded ("cle(#)"):
 This event indicates that the cell loss rate exceeds the threshold #.
 If the threshold is omitted in the requested events and observed
 events parameters, it is known by other means.  The optional decimal
 number is the number of dropped cells per 100,000 cells.  For
 example, cle(10) indicates cells are being dropped at a rate of 1 in
 10,000 cells.
 Packet loss exceeded ("ple(#)"):
 This event indicates that the packet loss rate exceeds the threshold
 #.  If the threshold is omitted in the requested events and observed
 events parameters, it is known by other means.  The optional decimal
 number is the number of dropped packets per 100,000 packets.  For
 example, ple(10) indicates packets are being dropped at a rate of 1
 in 10,000 packets.
 When the bearer connection uses an AAL2 CID within a multiplexed VCC
 rather than an entire VCC, the 'ple' event is used instead of 'cle'.
 The packets are AAL2 CPS PDUs.
 Quality alert ("qa"):
 This event indicates that the bearer path fails to any predetermined
 combination of quality criteria such as loss, delay, jitter etc.
 This criterion is not defined and is left to the application.  The
 gateway reports this quality violation to the call agent if armed to
 do so.

Kumar Informational [Page 34] RFC 3441 ATM MGCP Package January 2003

 Report failure ("of (#)"):
 This indicates a connection failure.  It can also indicate failure to
 establish a connection, in lieu of "sf".
 The most common response to these events is for the media gateway to
 delete the connection.  Some applications might choose to report an
 "of" with the appropriate reason code, a decimal number, optionally
 included in parentheses.  Reason codes are the same as for
 spontaneous deletes by the gateway.

5.0 Connection Parameters

 The MGCP connection parameters structure is returned in an autonomous
 delete connection message, and in a response to a delete or audit
 connection command.  The standard connections parameters [36] it
 contains are redefined below for ATM.  Also, a new extension
 parameter specific to the ATM package is defined.
 The standard connection parameters redefined for ATM are:
 Number of packets sent: If a VCC is assigned to the connection, this
 is the total number of ATM cells transmitted for the duration of the
 connection.  If a CID within an AAL2 VCC is assigned to the
 connection, it is the number of AAL2 common part sublayer (CPS)
 packets transmitted for the duration of the connection.
 Number of octets sent: If a VCC is assigned to the connection, this
 is the total number of ATM payload octets transmitted for the
 duration of the connection.  If a CID within an AAL2 VCC is assigned
 to the connection, this is the total number of AAL2 CPS payload
 octets transmitted for the duration of the connection.
 Number of packets received: If a VCC is assigned to the connection,
 this is the total number of ATM cells received for the duration of
 the connection.  If a CID within an AAL2 VCC is assigned to the
 connection, it is the number of AAL2 common part sublayer (CPS)
 packets received for the duration of the connection.
 Number of octets received: If a VCC is assigned to the connection,
 this is the total number of ATM payload octets received for the
 duration of the connection.  If a CID within an AAL2 VCC is assigned
 to the connection, this is the total number of AAL2 CPS payload
 octets received for the duration of the connection.
 Number of packets lost: If a VCC is assigned to the connection, this
 is the total number of ATM cells lost for the duration of the
 connection, in the direction towards the gateway.  If a CID within an

Kumar Informational [Page 35] RFC 3441 ATM MGCP Package January 2003

 AAL2 VCC is assigned to the connection, it is the number of AAL2
 common part sublayer (CPS) packets lost for the duration of the
 connection, in the direction towards the gateway.  If these losses
 cannot be assessed, then the gateway omits this parameter.
 Interarrival jitter: If a VCC is assigned to the connection, this is
 the interarrival jitter for ATM cells.  If a CID within an AAL2 VCC
 is assigned to the connection, this is the interarrival jitter for
 AAL2 common part sublayer (CPS) packets.  If this cannot be
 determined, then it is omitted or set to 0.
 Average Transmission Delay: This should be understood to be the
 average cell transmission delay in both cases: VCC assignment and CID
 assignment to the connection.  This requires the use of ATM
 performance monitoring techniques.  If it is not possible to assess
 this delay, it is omitted or set to 0.
 The following extension parameter is defined for the connection
 parameters structure:
 Connection qualification ("atm/CQ"): This qualifies the connection
 with enough granularity to be able to use the other connection
 parameters without a priori knowledge of network or connection type.
 Defined values are:
    1              ATM Virtual Circuit Connection (VCC)
    2              AAL2 Channel Identifier (CID)
    3              Direct transfer i.e., without an ATM or other
                   packet path
 When omitted, the connection parameters must be interpreted on one of
 the following bases:
  • The default interpretations for MGCP in Ref. 36.
  • The call agent's prior knowledge, if it governs the type of

network and connection through the network type 'nt' LCO [Ref.

       36] and/or the connection type 'ct' LCO defined here.
    *  The call agent's snooping of the local connection descriptor
       provided by one or more media gateway.  This is used to
       determine the network and connection type.
 An example of connection parameter encoding for an ATM VCC is the
 following:
 P: PS=1245, OS=59760, PR=1244, OR=59712, PL=20, JI=0, LA=0,atm/CQ=1

Kumar Informational [Page 36] RFC 3441 ATM MGCP Package January 2003

 Note that the PL value refers to the receive direction and is
 unrelated to PS.  Also, since atm/CQ=1, these parameters refer to ATM
 cells rather than to AAL2 CPS packets.
 As in other applications, any of these parameters can be omitted if
 not relevant to an application.  Also, the entire P: structure is
 optional.
 When connection parameters are audited, all parameters normally
 returned with a delete connection are returned.  This includes the
 connection qualification parameter, atm/CQ.
 The measurement or estimation of some or all of these connection
 parameters might not be feasible or beneficial in some applications.
 In such cases, these may be individually omitted, or the entire
 connection parameters structure, which is optional in MGCP, might be
 omitted.  Further, parameters which indicate impairments might be set
 to 0 to nullify their impact, if any.

6.0 Negotiation of Profiles and Codecs in ATM Applications

6.1 Consistency of Parameters

 For ATM networks, the "nt" local connection option in MGCP must be
 set to "ATM".
 In any ATM application, the following Local Connection Options should
 not be used:
    Type of service, L: t
    Resource reservation, L: r
 This is because the Local Connection Options listed in Table 6
 provide information equivalent to the L: t and L: r local connection
 options.
 The following Local Connection Option is not meaningful in the AAL1
 case and should not be used:
    Packetization period, L: p
 In AAL2 applications, the following Local Connection Options should
 not be used:
    Encoding algorithm, L: a
    Packetization period, L: p

Kumar Informational [Page 37] RFC 3441 ATM MGCP Package January 2003

 The following ATM Local Connection Options provide equivalent
 information in the AAL2 case:
 Profile list, L: atm/pfl
 Priority list of voice codec selections, L: atm/vsel
 Priority list of voiceband data passthrough codec selections,
 L: atm/dsel
 Priority list of fax codec selections, L: atm/fsel
 The use of a disallowed local connection option should be flagged
 with a return code of 524 (inconsistent local connection options).
 Although it is not recommended that these be ignored, it is
 recognized some applications choose to do so for the sake of backward
 compatibility.  Note that the inconsistency in this case is between
 the local connection option (e.g., L:a) and the application (e.g.,
 AAL2) which does not allow it.

6.2 Codec/Profile Negotiation in ATM Networks

 In AAL1 and AAL5 applications, codec negotiation is similar to the IP
 case, although some of the local connection options and SDP
 connection descriptor parameters are different.  See [18] for
 conventions for the use of the Session Description Protocol [26] in
 the ATM context.
 In AAL2 applications, the L:a and L:p parameters are disallowed.
 Profile negotiation takes the place of codec negotiation.  The
 remainder of this section addresses how this is done.
 The specifics of the AAL2 bearer are not germane to profile
 negotiation.  The bearer could be PVC-based or SVC-based, based on
 single-CID or multi-CID VCs, subcell multiplexed or not.
 The most general case involves different prioritized lists of
 profiles at the originating gateway, the terminating gateway, the
 originating call agent and the terminating call agent.  Whether these
 lists are based on network policies, end subscriber service level
 agreements or equipment design is immaterial to the profile
 negotiation that is done as part of the connection establishment
 process.  It is also irrelevant whether these lists are hardcoded
 defaults or provisionable.  In the connection establishment process,
 a series of ordered intersections is performed.  This leaves a single
 ordered list in the end.  The highest priority profile in this list
 is the selected profile.

Kumar Informational [Page 38] RFC 3441 ATM MGCP Package January 2003

 The call agent conveys its priority list through the pfl local
 connection option.  The gateway conveys intersection results through
 the media information line in SDP [18].  Whether these lists imply a
 real priority or not, a profile is, as a general rule, preferred to
 profiles that follow it in a list.
 Each media gateway has a policy for assigning priorities to different
 lists (inter-list priority) which is different from the positional
 ordering of profiles within a list (intra-list priority).  This
 policy might be a hardcoded default or provisioned.  The inter-list
 priority specifies an ordering of the following lists with respect to
 each other:
  • 'C-list', which is the priority list from the call agent,

received through L: atm/pfl.

  • 'R-list', which is the priority list from the remote end,

received through the SDP remote connection descriptor.

  • 'L-list', which is the local priority list, hardcoded or

provisioned.

 Depending on the application, different inter-list priorities may be
 used in cases where the gateway originates and terminates a call.
 The policy mentioned above will vary depending on the type,
 capabilities and deployment of the media gateway.  Network
 administrations or equipment vendors will provision/default this
 policy for various reasons such as resource usage optimization,
 quality of service, likelihood of finding a common profile etc.
 When doing an ordered intersection of lists, the intra-list
 priorities of the highest priority list are used.  Any profile that
 cannot be supported due to resource (bandwidth, processing power
 etc.)  limitations is eliminated from the intersection.
 In the absence of one or more of these lists, the remaining list(s)
 are used in the profile selection process.  If the call agent does
 not provide a list of profiles, the C-list is absent.  In this case,
 the intersection of the C-list, R-list and L-list simply becomes the
 intersection of the R-list and the L-list.  If the R-list is also
 absent, no intersection is performed and the result of this null
 operation is the L-list.  Previous values, if any, of the C-list and
 R-list are not used.

Kumar Informational [Page 39] RFC 3441 ATM MGCP Package January 2003

 The process of profile negotiation is as shown below:
        ORIGINATING                     TERMINATING
              GATEWAY                           GATEWAY
 (1) On receiving CRCX
     do a policy-based ordered
     intersection of the C-list,
     and L-list. No R-list present.
                       ---------------------------------->
                       (2)Send resulting ordered list
                          to the terminating gateway
                          via SDP.
                                             (3) On receiving CRCX do
                                                 a policy-based
                                                 ordered
                                                 intersection of the
                                                 C-list, R-list and
                                                 L-list.
                                             (4) The highest priority
                                                 profile in the
                                                 resulting
                                                 list is the
                                                 selected
                                                  profile.
                            <-----------------------------------
                             (5) Send selected profile
                                 to the originating gateway
                                 via SDP.
 Prior to receiving the final profile in step 5, if the originating
 gateway has indicated multiple profiles in step 2, the originating
 gateway does not always have a usable basis for decoding AAL2
 packets.  This is because a combination of packet length and UUI
 (user-to-user indication) codepoint range may indicate different
 codecs in different profiles.  The time lag between when the
 terminating gateways start sending AAL2 packets and when the
 originating gateway becomes aware of the selected AAL2 profile should
 be minimized so that any ensuing clipping of the front-end of the
 audio stream is tolerable for voice circuits.  It is unlikely that
 this will introduce errors in modem or fax circuits since these will
 not have entered their user data transfer phase at this time.
 When connection establishment is complete, there is only one profile
 associated with a connection.  This implies that both endpoints are
 ready to receive, on the fly, packets that comply with any row in the
 profile.  Some applications may elect to associate profile rows with

Kumar Informational [Page 40] RFC 3441 ATM MGCP Package January 2003

 one or more of the following service types: voice service, voiceband
 data (modem) passthrough service and fax service.  This binding can
 be by default, through provisioning or as part of profile negotiation
 during call establishment.  Such service type associations, when
 communicated to another entity, are advisory and do not limit the
 requirement for supporting, at any time, on-the-fly switches to any
 profile element.
 Media gateways can have internal default (or provisioned) bindings
 between service types and profile elements.  Note that not all of
 these bindings might be meaningful in an application context (e.g.,
 the fax service binding might be ignored and omitted).  As part of
 profile negotiation, applications might choose to coordinate those
 bindings that are meaningful.  When this is done, the vsel, dsel and
 fsel LCOs described in this document, and the vsel, dsel and fsel
 media attribute lines [18] are used to effect this coordination.
 Using these constructs, entities such as call agents and media
 gateways can indicate preferred bindings for the first, most
 preferred profile in a profile list.
 When performing ordered intersections of the C-list, L-list and
 R-list in the call flow above, media gateways MUST use the inter-list
 priority to choose between a service to profile row binding suggested
 by the call agent, the remote gateway or it own internal (provisioned
 or default) binding.  Thus, a service type to profile row binding
 inherits its relative priority from the profile list generated by the
 same source.  If the C-list has the highest priority, and the first
 profile in the C-list is selected as the first profile of the
 intersected list, then any service type to profile row bindings
 provided by the call agent via the vsel, dsel and fsel LCOs are
 associated with the first profile.  If the R-list has the highest
 priority, and the first profile in the R-list is selected as the
 first profile of the intersected list, then any service type to
 profile row bindings provided by the remote gateway via the vsel,
 dsel and fsel SDP attributes [18] are associated with the first
 profile.  If the L-list has the highest priority, then any internal
 (default or provisioned) service to profile row bindings are
 associated with the first profile.  At the end of profile negotiation
 (step 4 in the call flow above), there is one profile selected by the
 terminating media gateway.  It MAY convey any applicable service type
 to profile row bindings for this profile to the originating gateway
 via the vsel, dsel and fsel SDP attributes [18].
 If the first profile in the intersected list is not the first profile
 in the highest priority profile list, then any service to profile row
 bindings associated with the highest priority profile list cannot be
 used with the first (or only profile) in the intersected list.  In
 this case, the originating or terminating media gateway MUST attempt

Kumar Informational [Page 41] RFC 3441 ATM MGCP Package January 2003

 to associate internal (default or provisioned) service to profile row
 bindings with the first (or only profile) in the intersected list.
 Since there is more than one service type, it is possible that the
 service type to profile row bindings for the first profile in the
 intersected list be derived from different sources (the call agent,
 the remote media gateway, internal defaults or provisioning).  For
 consistency, if the voiceband data (passthrough) service mappings
 include fax, then a different set of fax service mappings cannot
 apply to the profile under consideration.  If applied in this case,
 the set of fax service mappings must include the same codecs, packet
 lengths and packetization periods as the voiceband data service
 mappings.  However, they may be in a different order.
 If the media gateway lumps fax service with voiceband data (modem)
 passthrough service, then it can ignore any fax service to profile
 row bindings provided by another entity such as the call agent or the
 remote gateway.  From the media gateway's perspective, there is no
 distinct fax service in this case.  In this case, the media gateway
 will not indicate a separate preference for the use of certain
 profile rows in conjunction with fax service.
 It is possible that the procedure described in this section for
 associating service types with profile rows fail to yield mappings
 between a given service type and the row(s) of the first profile in
 the intersected list of profiles.  This is acceptable since these
 bindings are merely indications of the preferred codecs and
 packetizations in the context of a given service.  They do not
 obviate the AAL2 requirement that, given a profile that is bound to a
 connection, a transmitter may switch to any profile row on the fly.
 An example of profile negotiation:
 The L-list at gateway #1, which is the originating gateway in this
 example, is:
    custom 100, itu 3, itu 1, itu 8

Kumar Informational [Page 42] RFC 3441 ATM MGCP Package January 2003

 The L-list at gateway #2, which is the terminating gateway in this
 example, is:
    itu 2, itu 3, itu 1, itu 5
 The originating call agent sends the following profile list (C-list)
 to the originating gateway in the first create connection command:
    itu 8, itu 9, atmf 7, itu 3, itu 1, custom 100
 Further, the originating call agent qualifies the first profile in
 its list with the following service type bindings:
    L: atm/vsel:"G729 10 10000", atm/dsel:"on PCMU 40 5000"
 There is no atm/fsel local connection option.  Facsimile is included
 with voiceband data in the atm/dsel local connection option.
 In step 1 at the originating gateway, there is no remote connection
 descriptor, hence no R-list.  The policy for originating calls at
 gateway #1 is:
    C-List > R-list > L-list
 where '>' means 'has higher priority than'.  The term 'R-list' can be
 omitted from this series of inequalities since, in case under study,
 profile negotiation does not include any further ordered
 intersections at the originating gateway.
 In accordance with this policy, the originating gateway performs an
 ordered intersection of the C-list and the L-list to produce:
    itu 8, itu 3, itu 1, custom 100
 Since the C-list has the highest priority and the first profile in
 the intersected profile list is also the first profile in the C-list,
 the service bindings provided by the originating call agent are
 associated with the first profile, itu 8.  The originating gateway
 sends this result(intersected profile list and service bindings for
 the first profile, itu 8) via the SDP remote session descriptor to
 the terminating gateway.  The service bindings are expressed as
 follows [18]:
    a=vsel:G729 10 10000
    a=dsel:on PCMU 40 5000

Kumar Informational [Page 43] RFC 3441 ATM MGCP Package January 2003

 The intersected profile list produced by gateway 1 becomes the R-list
 for gateway #2.  The terminating call agent sends the following
 profile list (C-list) to the terminating gateway in the first create
 connection command:
    itu 1, itu 4,   itu 3, custom 110, custom 100, itu 2
 Any service bindings (not shown) sent by the terminating call agent
 apply to the first profile in this list, itu 1.
 The policy for terminating calls at gateway #2 is:
    R-list > L-list > C-list
 Using this policy, gateway #2 produces the following ordered
 intersection of R-list, L-list and C-list:
    itu 3, itu 1
 The first profile in this list, itu 3, is to be used for this
 connection.  Gateway 2 indicates this to the call agent through the
 SDP local connection descriptor.
 Note that the service bindings provided by the originating gateway
 have not been specified with respect to itu 3.  Therefore, these
 cannot be used even though the R-list has the highest priority at the
 terminating gateway.  Any existing internal (default or provisioned)
 service bindings for AAL2 profile itu 3 must be associated by the
 terminating gateway with the selected profile, itu 3.  Those service
 bindings that are internally unavailable are left unspecified.
 Since the internal service type bindings do exist for the profile itu
 3 at the terminating gateway, they are selected and bound to the
 connection.  In these, fax service is lumped with voiceband data
 passthrough.  These bindings are indicated to the originating gateway
 via the following SDP media attribute lines:
    a=vsel:G726-32 20 5000 G726-24 15 5000
    a=dsel:on PCMU 40 5000 G726-40 25 5000

Kumar Informational [Page 44] RFC 3441 ATM MGCP Package January 2003

 The vsel line maps voice service to certain rows in the itu 3 profile
 table.  The dsel line maps voiceband data service to certain rows in
 the itu 3 profile table.  The "on" in the dsel line indicates that
 voiceband data includes fax, otherwise a separate fsel line might
 have been used.  Two codecs each are indicated for voice and for
 voiceband data, with the first codec being the preferred one.
 Although the originating gateway is not constrained by these advisory
 indications of profile element to service type mapping, applications
 may choose to limit on-the-fly switches based on the current service
 state (voice, voiceband data etc.).  If done, this provides greater
 simplicity at the expense of flexibility.

7.0 Security Considerations

 The ATM package extends the base Media Gateway Control Protocol
 (MGCP) [36].  This package specifies no additional security
 requirements or recommendations over those of the base MGCP protocol.

8.0 IANA Considerations

 The ATM package described in this document has been registered as an
 MGCP package under the name "atm", without the quotes.  The current
 version of this package is 0 (default).  This registration has been
 completed per the IANA considerations in the MGCP specification [36].
 The contact for the MGCP ATM package is the author of this document
 (Section 12).

9.0 References

 [1]  ITU-T I.366.1, B-ISDN ATM Adaptation Layer Specification: Type 1
      AAL.
 [2]  ITU-T I.366.2, AAL Type 2 Reassembly Service Specific
      Convergence Sublayer for Trunking, Nov. 2000.
 [3]  af-vtoa-0113.000, ATM trunking using AAL2 for narrowband
      services.
 [4]  ITU Q. 2965.1, Digital subscriber signalling system no.2 (DSS 2)
      - Support of Quality of Service classes.
 [5]  ITU Q.2961, Digital subscriber signalling system no.2 (DSS 2) -
      additional traffic parameters.  Also, Amendment 2 to Q.2961.
 [6]  ATMF UNI 4.0 Signaling Specification, af-sig-0061.000.

Kumar Informational [Page 45] RFC 3441 ATM MGCP Package January 2003

 [7]  ITU Q. 2965.2, Digital subscriber signalling system no.2 (DSS 2)
      - Signalling of individual Quality of Service parameters.
 [8]  ATMF Traffic Management Specification, Version 4.1, af-tm-
      0121.000.
 [9]  I.356, BISDN ATM layer cell transfer performance.
 [10] ITU-T I.363.2, B-ISDN ATM Adaptation Layer Specification: Type 2
      AAL, Sept. 1997.
 [11] ITU-T I.366.1, Segmentation and Reassembly Service Specific
      Convergence Sublayer for AAL Type 2, June 1998.
 [12] H.323-2, Packet-based multimedia communications systems.
 [13] af-vtoa-0083.000, Voice and Telephony Over ATM to the Desktop.
 [14] Q.2110, B-ISDN ATM adaptation layer - service specific
      connection oriented protocol (SSCOP).
 [15] I.365.1,Frame relaying service specific convergence sublayer
      (FR-SSCS).
 [16] I.365.2, B-ISDN ATM adaptation layer sublayers: service specific
      coordination function to provide the connection oriented network
      service.
 [17] I.365.3, B-ISDN ATM adaptation layer sublayers: service specific
      coordination function to provide the connection-oriented
      transport service.
 [18] Kumar, R. and M. Mostafa, "Conventions for the use of the
      Session Description Protocol (SDP) for ATM Bearer Connections",
      RFC 3108, May 2001.
 [19] ITU I.371, Traffic Control and Congestion Control in the BISDN.
 [20] ATMF Circuit Emulation Service (CES) Interoperability
      Specification, af-vtoa-0078.000.
 [21] af-vmoa-0145.000, Voice and Multimedia over ATM, Loop Emulation
      Service using AAL2.
 [22] ITU-T H.222.1, Multimedia multiplex and synchronization for
      audiovisual communication in ATM environments.

Kumar Informational [Page 46] RFC 3441 ATM MGCP Package January 2003

 [23] FRF.5, Frame Relay/ATM PVC Network Interworking Implementation
      Agreement.
 [24] FRF.8, Frame Relay/ATM PVC Service Interworking Implementation
      Agreement.
 [25] FRF.11, Voice over Frame Relay Implementation Agreement.
 [26] Handley, M. and V. Jacobson, "SDP: Session Description
      Protocol", RFC 2327, April 1998.
 [27] ITU-T I.363.5, B-ISDN ATM Adaptation Layer Specification: Type 5
      AAL, Aug. 1996.
 [28] I.365.4, B-ISDN ATM adaptation layer sublayers: Service specific
      convergence sublayer for HDLC applications.
 [29] ITU-T Q.2931, B-ISDN Application Protocol for Access Signaling.
 [30] ITU Q.765.5, Application Transport Mechanism - Bearer
      Independent Call Control.
 [31] http://www.3gpp.org/ftp/Specs for specifications related to
      3GPP, including AMR codecs.
 [32] ITU Q.931, Digital Subscriber Signaling System No. 1: Network
      Layer.
 [33] ITU Q.763, SS7 - ISUP formats and codes.
 [34] http://www.iana.org/assignments/rtp-parameters
 [35] ATMF Voice and Telephony over ATM - ATM Trunking using AAL1 for
      Narrowband Services, version 1.0, af-vtoa-0089.000, July 1997.
 [36] Andreasen, F. and B. Foster, "Media Gateway Control Protocol
      (MGCP) Version 1.0", RFC 3435, January 2003.
 [37] Handley, M. and V. Jacobson, "SDP: Session Description
      Protocol", RFC 2327, April 1998.
 [38] Foster, B., "MGCP CAS Packages", RFC 3064, February 2001.

Kumar Informational [Page 47] RFC 3441 ATM MGCP Package January 2003

10.0 Acronyms

 AAL  ATM Adaptation Layer
 ABR  Available Bit Rate
 ABT/DT ATM Block Transfer/Delayed Transmission
 ABT/IT ATM Block Transfer/Immediate Transmission
 ATM  Asynchronous Transfer Mode
 ATMF ATM Forum
 BCG  Bearer Connection Group
 CAS  Channel Associated Signaling
 CBR  Constant Bit Rate
 CDV  Cell Delay Variation
 CDVT Cell Delay Variation Tolerance
 CID  Channel Identifier
 CLR  Cell Loss Ratio
 CPS  Common Part Sublayer
 DBR  Deterministic Bit Rate
 FEC  Forward Error Correction
 FRF  Frame Relay Format
 GFR  Guaranteed Frame Rate
 GWID Gateway Identifier
 IP   Internet Protocol
 ITU  International Telecommunications Union
 LCO  Local Connection Option
 MBS  Maximum Burst Size
 MCR  Minimum Cell Rate
 MFS  Maximum Frame Size
 MGCP Media Gateway Control Protocol
 nrt-VBR   Non-real-time Variable Bit Rate
 NSAP Network Service Access Point
 PCR  Peak Cell Rate
 PDU  Protocol Data Unit
 PVC  Permanent Virtual Circuit
 QoS  Quality of Service
 rt-VBR    Real-time Variable Bit Rate
 SAR  Segmentation and Re-assembly
 SCR  Sustained Cell Rate
 SDT  Structured Data Transfer
 SDU  Service Data Unit
 SPVC Switched Permanent Virtual Circuit
 SRTS Synchronous Residual Time-Stamp
 SSCOP Service-specific Connection Oriented Protocol
 SSSAR Service-specific Segmentation and Re-assembly
 SVC  Switched Virtual Circuit
 TDM  Time-Division Multiplexing
 UBR  Unspecified Bit Rate
 UDT  Unstructured Data Transfer
 VC   Virtual Circuit

Kumar Informational [Page 48] RFC 3441 ATM MGCP Package January 2003

 VCCI Virtual Circuit Connection Identifier
 VCI  Virtual Circuit Identifier
 VP   Virtual Path
 VPCI Virtual Path Connection Identifier
 VPI  Virtual Path Identifier

11.0 Acknowledgements

 The author wishes to thank several colleagues at Cisco and the
 industry who have contributed towards the development of the MGCP ATM
 package, and who have implemented and tested these constructs.
 Special thanks are due to Bill Foster, Flemming Andreasen, Raghu
 Thirumalai Rajan, Joe Stone, Hisham Abdelhamid, Joseph Swaminathan,
 Sushma Srikanth, Amit Agrawal, Mohamed Mostafa, Latha Idury, David
 Auerbach and Robert Biskner of Cisco systems and to Mahamood Hussain
 of Hughes Software Systems for their contributions.  Finally, thanks
 are due to Scott Bradner for guiding the final phase of the
 publication of this document.

12.0 Author's Address

 Rajesh Kumar
 Cisco Systems, Inc.
 170 West Tasman Drive
 San Jose, CA 95134-1706
 Phone: 1-408-527-0811
 EMail: rkumar@cisco.com

Kumar Informational [Page 49] RFC 3441 ATM MGCP Package January 2003

13.0 Full Copyright Statement

 Copyright (C) The Internet Society (2003).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

 Funding for the RFC Editor function is currently provided by the
 Internet Society.

Kumar Informational [Page 50]

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