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rfc:rfc1754

Network Working Group M. Laubach Request for Comments: 1754 Com21, Inc. Category: Informational January 1995

                    IP over ATM Working Group's
       Recommendations for the ATM Forum's Multiprotocol BOF
                             Version 1

Status of this Memo

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

1. Abstract

 This document represents an initial list of requirements submitted to
 the ATM Forum's Multiprotocol BOF for the operation of IP over ATM
 networks as determined by the IETF IP over ATM Working Group and
 other working groups. This RFC is issued for the benefit of community
 members.  The information contained in this document is accurate as
 of the date of publication, but is subject to change.  Subsequent
 RFCs will reflect such changes.
 The content of this memo was submitted by the IETF Liaison to the ATM
 Forum as contribution number 94-0954 in the ATM Forum's documentation
 process on 14 September 1994.

2. Notice

 This contribution has been prepared to assist the ATM Forum.  This
 document is offered to the Forum as a basis for discussion between
 the ATM Forum Multiprotocol BOF and the IETF.  The statements are
 subject to change in form and content after further study and
 discussion.  Specifically, the IETF reserves reserves the right to
 add to, amend or modify the statements contained herein.

3. Introduction

 The following is the charter statement from the Internet Engineering
 Task Force's (IETF) IP over ATM Working Group (IPATM WG).  It is
 being reproduced here for the benefit of those in the ATM Forum who
 may not be familiar with it:
 "The IP over ATM Working Group will focus on the issues involved in
 running internetworking protocols over Asynchronous Transfer Mode
 (ATM) networks.  The final goal for the Working Group is to produce

Laubach [Page 1] RFC 1754 IPATM WG ATM Forum Recommendations V1 January 1995

 standards for the TCP/IP protocol suite and recommendations which
 could be used by other internetworking protocol standards (e.g., ISO
 CLNP and IEEE 802.2 Bridging).
 The Working Group will initially develop experimental protocols for
 encapsulation, multicasting, addressing, address resolution, call set
 up, and network management to allow the operation of internetwork
 protocols over an ATM network.  The Working Group may later submit
 these protocols for IETF standardization.
 The Working Group will not develop physical layer standards for ATM.
 These are well covered in other standards groups and do not need to
 be addressed in this Group.
 The Working Group will develop models of ATM internetworking
 architectures.  This will be used to guide the development of
 specific IP over ATM protocols.
 The Working Group will also develop and maintain a list of technical
 unknowns that relate to internetworking over ATM.  These will be used
 to direct future work of the Working Group or be submitted to other
 standards or research groups as appropriate.
 The Working Group will coordinate its work with other relevant
 standards bodies (e.g., ANSI T1S1.5) to insure that it does not
 duplicate their work and that its work meshes well with other
 activities in this area.  The Working Group will select among ATM
 protocol options (e.g., selection of an adaptation layer) and make
 recommendations to the ATM standards bodies regarding the
 requirements for internetworking over ATM where the current ATM
 standards do not meet the needs of internetworking."
 Historically, a large number of IETF IPATM WG participants are
 employees of companies who are principal members of the ATM Forum.
 Requirements between the two organizations have been communicated
 informally by these participants.  With the establishment of the ATM
 Forum's Multiprotocol BOF activities, it has become prudent now to
 document IETF requirements in a more formal fashion.
 At the July 1994 meeting of the IETF in Toronto, Canada, a request
 was presented to the IP over ATM Working Group by the ATM Forum
 Liaison, Drew Perkins, for the working group to prepare a list of
 requirements as input to the ATM Forum's Multiprotocol BOF
 activities.  This document is a response to that request.

Laubach [Page 2] RFC 1754 IPATM WG ATM Forum Recommendations V1 January 1995

4. List of Requirements for Consideration

4.1 Standardization & Logistics

  1. Formal communications between the IETF and the ATM Forum

should be made via IETF <> ATM Forum Liaison(s), specific

      written communications (such as this document), and/or
      presentations made at official IETF or ATM Forum meetings.
  1. IETF standards define how the TCP/IP protocol suite is defined,

deployed, and carried over specific network technologies,

      including ATM networks [1][2][8].
  1. Any formal communications that affect the IETF standards

or processes must be made publicly available as the IETF is

      a public international standards body.  Ideally, such
      communications should be written as Internet Drafts [1], the
      IETF's equivalent to incoming contributions.
  1. We invite and encourage ATM Forum members to participate in

the IETF standards process. See [1], [2], and [8] for

      information on how to participate.

4.2 IPv4 Encapsulation

  1. RFC 1483 [3] and RFC 1577 [4] define how IP is encapsulated

and carried over ATM networks. The IPATM WG requests that any

      ATM Forum Multiprotocol work support these standards as
      specified, and that any future changes to them be made via the
      IETF standards process.

4.3 Routing

  1. RFC 1577 defines the default Logical IP Subnet (LIS) model.
  1. The IETF Routing over Large Clouds Working Group is developing

the Next Hop Resolution Protocol, which allows the incremental

      optimization of routing (and subnets) by routing datagrams
      over preferential ATM paths [9].
  1. The IETF IP over ATM Working Group will be working on the

next generation IP over ATM standards after RFC 1577 moves

      from draft to proposed status.  Requirements to the ATM
      Forum will be forthcoming.
  1. ATM signaling should give an indication of connection

over LAN or WAN and include feedback of time vs byte

      charging.

Laubach [Page 3] RFC 1754 IPATM WG ATM Forum Recommendations V1 January 1995

4.4 Security

  1. ATM signaling should support a user information element

that is used to convey security and authentication information

      between IP members and applications.  The IETF IPATM WG would
      like to define the IP specific content of this IE.

4.5 Broadcast and Multicast

  1. The IPATM WG is currently discussing models of how best to map

IP multicast facilities onto ATM facilities. While this work is

      preliminary, the IETF does support the ATM Forum's currently
      planned multicasting enhancements, such as leaf-initiated joins
      and support of multiple multicast congestion management
      policies.  A further list of requirements will be presented at a
      later time.

4.6 Signaling and Addressing

  1. The IPATM WG is currently producing a specification for using

UNI 3.0 and 3.1 signaling to support RFCs 1483 and 1577. This

      specification will be published as an informational reference
      for UNI 3.0 signaling, and as a proposed standard for UNI 3.1
      signaling following UNI 3.1's ratification and official
      publication.
  1. IPv6 packets will include a Flow ID field intended to support

service classes in some way. Until the semantics of this field

      are fully defined it is hard to say much, but presumably a soft
      mapping between this and the VC to be used is desirable.  A
      further list of requirements will be presented at a later time.
  1. IPv6 addresses will be 16 bytes and there will likely be a

defined embedding of them inside 20-byte NSAP format. There will

      also likely be a mapping of US-GOSIP-like NSAPs into IPv6
      addresses (deleting the unuseful bytes), but that is still
      controversial in the IPv6 discussions.  A further list of
      requirements will be presented at a later time.

Laubach [Page 4] RFC 1754 IPATM WG ATM Forum Recommendations V1 January 1995

4.7 Quality of Service, Performance, and Traffic Management

  1. ATM should support extremely bursty applications with

significant elasticity in their bandwidth demands.

  1. ATM should support elastic applications as defined in

RFC-1633 [7] very efficiently. That means enable high

      bottleneck utilization while keeping delay reasonably bounded
      (i.e., doubling delay wouldn't be terrible for elastic apps).
      This should not be at the expense of delay sensitive classes
      of service.
  1. ATM should provide a a class of service which strives to

cooperate with existing TCP congestion avoidance, thereby

      explicitly providing support not only for directly ATM-attached
      and -aware endstations, but also for endstations on LANs (or
      using LAN Emulation) that are using current TCP implementations
      and interconnected via ATM-attached bridges and routers.
  1. Predictive QoS should be supported in addition to guaranteed QoS

to support applications which are somewhat tolerant of delay

      variation and low levels of loss.
  1. IP uses both point-to-point and point-to-multipoint (future)

connections. To satisfy IP's needs an ABR-like service

      would need to be applicable to both types of connections [6].
  1. No specification of minimum or maximum bandwidths by the ATM

end-systems [6].

  1. As simple as possible [6].
  1. Full line-rate transmission over otherwise-idle links [6].
  1. When end-to-end delay through the network is less than 1 second,

the cell loss for AAL5 frames over an ABR-like service should be

      on the order of 3 in 10**8 cells for 1500 byte frames, or 3 in
      10**9 cells for 18 Kbyte frames [6].

5. Security Considerations

 Security issues raised in this memo will be addressed by the IETF IP
 over ATM Working Group and presented in subsequent updates to this
 memo.

Laubach [Page 5] RFC 1754 IPATM WG ATM Forum Recommendations V1 January 1995

6. Acknowledgement

 The basis of this memo is a summary of comments made on the email
 discussion list of the IP over ATM Working Group.  The contribution
 was reviewed by Drew Perkins and Andy Malis as a sanity check before
 submission to the ATM Forum.

7. References

 [1]  IETF Secretariat and G. Malkin, "The Tao of the IETF - A Guide
      for New Attendees of the Internet Engineering Task Force",
      FYI 17, RFC 1718, CNRI, Xylogics, Inc., November 1994.
 [2]  Internet Architecture Board, and Internet Engineering Steering
      Group, "The Internet Standards Process -- Revision 2", RFC 1602,
      IAB, IESG, March 1994.
 [3]  Heinanen, J., "Multiprotocol Encapsulation over ATM Adaptation
      Layer 5", RFC 1483, Telecom Finland, July 1993.
 [4]  Laubach, M., "Classical IP and ARP over ATM", RFC 1577,
      Hewlett-Packard Laboratories, January 1994.
 [5]  Deering, S., "Host Extensions for IP Multicasting", STD 5,
      RFC 1112, Stanford University, August 1989.
 [6]  McCloghrie, K., "Lan-Emulation's Needs for Traffic Management",
      ATM-Forum/94-0533, ATM Forum, June 1994.
 [7]  Braden, R., Clark, D., and S. Shenker, "Integrated Services
      in the Internet Architecture: an Overview", RFC 1633,
      USC/Information Sciences Institute, MIT, Xerox PARC, June 1994.
 [8]  Postel, J., Editor, "Internet Official Protocol Standards",
      STD 1, RFC 1720, USC/Information Sciences Institute, July 1994.
 [9]  Malis, A., "Routing Over Large Clouds Liaison to the ATM Forum
      Multiprotocol BOF", ATM-Forum/94-0766, ATM Forum,
      September 1994.

Laubach [Page 6] RFC 1754 IPATM WG ATM Forum Recommendations V1 January 1995

8. IETF <> ATM Forum Liaison

 Drew Perkins
 FORE Systems, Inc.
 174 Thornhill Road
 Warrendale, PA 15086
 Phone: (412) 772-6527
 Fax:   (412) 772-6500
 Email: ddp@fore.com

9. Author's Address

 Mark Laubach
 Com21, Inc.
 2113 Landings Drive
 Mountain View, CA 94043
 Phone: (415) 254-5882
 Fax:   (415) 254-5883
 EMail: laubach@com21.com

Laubach [Page 7]

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