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rfc:rfc3154

Network Working Group J. Kempf Request for Comments: 3154 C. Castelluccia Category: Informational P. Mutaf

                                                           N. Nakajima
                                                               Y. Ohba
                                                             R. Ramjee
                                                          Y. Saifullah
                                                           B. Sarikaya
                                                                 X. Xu
                                                           August 2001
            Requirements and Functional Architecture for
                   an IP Host Alerting Protocol

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 (2001).  All Rights Reserved.

Abstract

 This document develops an architecture and a set of requirements
 needed to support alerting of hosts that are in dormant mode.  The
 architecture and requirements are designed to guide development of an
 IP protocol for alerting dormant IP mobile hosts, commonly called
 paging.

Kempf, et al. Informational [Page 1] RFC 3154 Paging Requirements August 2001

Table of Contents

 1. Introduction ...................................................3
 2. Terminology ....................................................3
 3. Security Considerations ........................................3
  3.1.   DoS Amplification .........................................3
  3.2.   Queue Overflow ............................................4
  3.3.   Selective DoS against Hosts ...............................4
 4. Requirements ...................................................5
  4.1.   Impact on Power Consumption ...............................5
  4.2.   Scalability ...............................................5
  4.3.   Control of Broadcast/Multicast/Anycast ....................5
  4.4.   Efficient Signaling for Inactive Mode .....................6
  4.5.   No Routers ................................................6
  4.6.   Multiple Dormant Modes ....................................6
  4.7.   Independence of Mobility Protocol .........................6
  4.8.   Support for Existing Mobility Protocols ...................6
  4.9.   Dormant Mode Termination ..................................6
  4.10.  Network Updates ...........................................6
  4.11.  Efficient Utilization of L2 ...............................7
  4.12.  Orthogonality of Paging Area and Subnets ..................7
  4.13.  Future L3 Paging Support ..................................7
  4.14.  Robustness Against Failure of Network Elements ............7
  4.15.  Reliability of Packet Delivery ............................7
  4.16.  Robustness Against Message Loss ...........................7
  4.17.  Flexibility of Administration .............................7
  4.18.  Flexibility of Paging Area Design .........................8
  4.19.  Availability of Security Support ..........................8
  4.20.  Authentication of Paging Location Registration ............8
  4.21.  Authentication of Paging Area Information .................8
  4.22.  Authentication of Paging Messages .........................8
  4.23.  Paging Volume .............................................8
  4.24.  Parsimonious Security Messaging ...........................8
  4.25.  Noninterference with Host's Security Policy ...............8
  4.26.  Noninterference with End-to-end Security ..................9
  4.27.  Detection of Bogus Correspondent Nodes ....................9
 5. Functional Architecture ........................................9
  5.1.   Functional Entities .......................................9
  5.2.   Interfaces ...............................................10
  5.3.   Functional Architecture Diagram ..........................12
 6. Acknowledgements ..............................................12
 7. References ....................................................13
 8. Authors' Addresses ............................................13
 9. Full Copyright Statement ......................................16

Kempf, et al. Informational [Page 2] RFC 3154 Paging Requirements August 2001

1. Introduction

 In [1], a problem statement was developed to explain why an IP
 protocol was desirable for alerting hosts in dormant mode, commonly
 called paging.  In this document, a set of requirements is developed
 for guiding the development of an IP paging protocol.  Based on the
 requirements, an architecture is developed to represent the
 functional relationships between logical functional entities
 involved.

2. Terminology

 Please see [1] for definition of terms used in describing paging.  In
 addition, this document defines the following terms:
    Wide Casting - Either broadcasting or multicasting.
       Inactive Mode - The host is no longer listening for any
       packets, not even periodically, and not sending packets.  The
       host may be in a powered off state, it may have shut down all
       interfaces to drastically conserve power, or it may be out of
       range of a radio access point.

3. Security Considerations

 An IP paging protocol introduces new security issues.  In this
 section, security issues with relevance to formulating requirements
 for an IP paging protocol are discussed.

3.1. DoS Amplification

 A DoS (Denial-of-Service) or DDoS (Distributed DoS) attack generally
 consists of flooding a target network with bogus IP packets in order
 to cause degraded network performance at victim nodes and/or routers.
 Performance can be degraded to the point that the network cannot be
 used.  Currently, there is no preventive solution against these
 attacks, and the impacts can be very important.
 In general a DoS attacker profits from a so-called "amplifier" in
 order to increase the damage caused by his attack.  Paging can serve
 for an attacker as a DoS amplifier.
 An attacker (a malicious correspondent node) can send large numbers
 of packets pretending to be sent from different (bogus) correspondent
 nodes and destined for large numbers of hosts in inactive and dormant
 modes.  This attack, in turn, will be amplified by the paging agent
 which wide casts paging messages over a paging area, resulting in
 more than one networks being flooded.  Clearly, the damage can be

Kempf, et al. Informational [Page 3] RFC 3154 Paging Requirements August 2001

 more important in wireless networks that already suffer from scarce
 radio bandwidth.
 Alternatively, an attacker can sort out a host which:
    1. sends periodic messages declaring that it is in dormant mode,
    2. never replies to paging requests.
 Such a node may be the attacker's node itself, or a second node
 participating in the attack.
 That node is never in inactive mode because of behavior 1 above.  In
 this case, the attacker can send large numbers of packets destined
 for that host which periodically declares that it is in dormant mode
 but never replies to paging messages.  The impact will be the same as
 above however in this case the attack will be amplified indefinitely.

3.2. Queue Overflow

 For reliability reasons, the paging protocol may need to make
 provisions for a paging queue where a paging request is buffered
 until the requested host replies by sending a location registration
 message.
 An attacker can exploit that by sending large numbers of packets
 having different (bogus) correspondent node addresses and destined
 for one or more inactive hosts.  These packets will be buffered in
 the paging queue.  However, since the hosts are inactive, the paging
 queue may quickly overflow, blocking the incoming traffic from
 legitimate correspondent nodes.  As a result, all registered dormant
 hosts may be inaccessible for a while.  The attacker can re-launch
 the attack in a continuous fashion.
 An attacker together with a bogus host that fails to respond to pages
 can overflow the buffering provided to hold packets for dormant mode
 hosts.  If the attacker keeps sending packets while the dormant mode
 host fails to reply, the buffer can overflow.

3.3. Selective DoS against Hosts

 The following vulnerabilities already exist in the absence of IP
 paging.  However, they are included here since they can affect the
 correct operation of the IP paging protocol.
 These vulnerabilities can be exploited by an attacker in order to
 eliminate a particular host.  This, in turn, can be used by an
 attacker as a stepping stone to launch other attacks.

Kempf, et al. Informational [Page 4] RFC 3154 Paging Requirements August 2001

 Forced Battery Consumption
 An attacker can frequently send packets to a host in order to prevent
 that host from switching to dormant mode.  As a result the host may
 quickly run out of battery.
 Bogus Paging Areas
 An attacker can periodically emit malicious packets in order to
 confuse one or more hosts about their actual locations.  Currently,
 there is no efficient way to authenticate such packets.
 In the case of IP paging, these packets may also contain bogus paging
 area information.  Upon receipt of such a packet, a host may move and
 send a location registration message pointing to a non-existing or
 wrong paging area.  The functional entities of the IP paging protocol
 may loose contact with the host.
 More importantly, this attack can serve for sorting out a host which
 shows the behaviors 1 and 2 described in Section 3.1.
 Bogus Paging Agents
 An attacker can wide cast fake paging messages pretending to be sent
 by a paging agent.  The impacts will be similar to the ones described
 in Sections 4.1 and 4.3.1.  However, depending on how the IP paging
 protocol is designed, additional harm may be caused.

4. Requirements

 The following requirements are identified for the IP paging protocol.

4.1. Impact on Power Consumption

 The IP paging protocol MUST minimize impact on the Host's dormant
 mode operation, in order to minimize excessive power drain.

4.2. Scalability

 The IP paging protocol MUST be scalable to millions of Hosts.

4.3. Control of Broadcast/Multicast/Anycast

 The protocol SHOULD provide a filter mechanism to allow a Host prior
 to entering dormant mode to filter which broadcast/multicast/anycast
 packets active a page.  This prevents the Host from awakening out of
 dormant mode for all broadcast/multicast/anycast traffic.

Kempf, et al. Informational [Page 5] RFC 3154 Paging Requirements August 2001

4.4. Efficient Signaling for Inactive Mode

 The IP paging protocol SHOULD provide a mechanism for the Tracking
 Agent to determine whether the Host is in inactive mode, to avoid
 paging when a host is completely unreachable.

4.5. No Routers

 Since the basic issues involved in handling mobile routers are not
 well understood and since mobile routers have not exhibited a
 requirement for paging, the IP paging protocol MAY NOT support
 routers.  However, the IP paging protocol MAY support a router acting
 as a Host.

4.6. Multiple Dormant Modes

 Recognizing that there are multiple possible dormant modes on the
 Host, the IP paging protocol MUST work with different implementations
 of dormant mode on the Host.

4.7. Independence of Mobility Protocol

 Recognizing that IETF may support multiple mobility protocols in the
 future and that paging may be of value to hosts that do not support a
 mobility protocol, the IP paging protocol MUST be designed so there
 is no dependence on the underlying mobility protocol or on any
 mobility protocol at all.  The protocol SHOULD specify and provide
 support for a mobility protocol, if the Host supports one.

4.8. Support for Existing Mobility Protocols

 The IP paging protocol MUST specify the binding to the existing IP
 mobility protocols, namely mobile IPv4 [2] and mobile IPv6 [3].  The
 IP paging protocol SHOULD make use of existing registration support.

4.9. Dormant Mode Termination

 Upon receipt of a page (either with or without an accompanying L3
 packet), the Host MUST execute the steps in its mobility protocol to
 re-establish a routable L3 link with the Internet.

4.10. Network Updates

 Recognizing that locating a dormant mode mobile requires the network
 to have a rough idea of where the Host is located, the IP paging
 protocol SHOULD provide the network a way for the Paging Agent to
 inform a dormant mode Host what paging area it is in and the IP
 paging protocol SHOULD provide a means whereby the Host can inform

Kempf, et al. Informational [Page 6] RFC 3154 Paging Requirements August 2001

 the Target Agent when it changes paging area.  The IP paging protocol
 MAY additionally provide a way for the Host to inform the Tracking
 Agent what paging area it is in at some indeterminate point prior to
 entering dormant mode.

4.11. Efficient Utilization of L2

 Recognizing that many existing wireless link protocols support paging
 at L2 and that these protocols are often intimately tied into the
 Host's dormant mode support, the IP paging protocol SHOULD provide
 support to efficiently utilize an L2 paging protocol if available.

4.12. Orthogonality of Paging Area and Subnets

 The IP paging protocol MUST allow an arbitrary mapping between
 subnets and paging areas.

4.13. Future L3 Paging Support

 Recognizing that future dormant mode and wireless link protocols may
 be designed that more efficiently utilize IP, the IP paging protocol
 SHOULD NOT require L2 support for paging.

4.14. Robustness Against Failure of Network Elements

 The IP paging protocol MUST be designed to be robust with respect to
 failure of network elements involved in the protocol.  The self-
 healing characteristics SHOULD NOT be any worse than existing routing
 protocols.

4.15. Reliability of Packet Delivery

 The IP paging protocol MUST be designed so that packet delivery is
 reliable to a high degree of probability.  This does not necessarily
 mean that a reliable transport protocol is required.

4.16. Robustness Against Message Loss

 The IP paging protocol MUST be designed to be robust with respect to
 loss of messages.

4.17. Flexibility of Administration

 The IP paging protocol SHOULD provide a way to flexibly auto-
 configure Paging Agents to reduce the amount of administration
 necessary in maintaining a wireless network with paging.

Kempf, et al. Informational [Page 7] RFC 3154 Paging Requirements August 2001

4.18. Flexibility of Paging Area Design

 The IP paging protocol MUST be flexible in the support of different
 types of paging areas.  Examples are fixed paging areas, where a
 fixed set of bases stations belong to the paging area for all Hosts,
 and customized paging areas, where the set of base stations is
 customized for each Host.

4.19. Availability of Security Support

 The IP paging protocol MUST have available authentication and
 encryption functionality at least equivalent to that provided by
 IPSEC [5].

4.20. Authentication of Paging Location Registration

 The IP paging protocol MUST provide mutually authenticated paging
 location registration to insulate against replay attacks and to avoid
 the danger of malicious nodes registering for paging.

4.21. Authentication of Paging Area Information

 The IP paging protocol MUST provide a mechanism for authenticating
 paging area information distributed by the Paging Agent.

4.22. Authentication of Paging Messages

 The IP paging protocol MUST provide a mechanism for authenticating L3
 paging messages sent by the Paging Agent to dormant mode Hosts. The
 protocol MUST support the use of L2 security mechanisms so
 implementations that take advantage of L2 paging can also be secured.

4.23. Paging Volume

 The IP paging protocol SHOULD be able to handle large numbers of
 paging requests without denying access to any legitimate Host nor
 degrading its performance.

4.24. Parsimonious Security Messaging

 The security of the IP paging protocol SHOULD NOT call for additional
 power consumption while the Host is in dormant mode, nor require
 excessive message exchanges.

4.25. Noninterference with Host's Security Policy

 The IP paging protocol MUST NOT impose any limitations on a Host's
 security policies.

Kempf, et al. Informational [Page 8] RFC 3154 Paging Requirements August 2001

4.26. Noninterference with End-to-end Security

 The IP paging protocol MUST NOT impose any limitations on a Host's
 ability to conduct end-to-end security.

4.27. Detection of Bogus Correspondent Nodes

 The IP paging protocol SHOULD make provisions for detecting and
 ignoring bogus correspondent nodes prior to paging messages being
 wide cast on behalf of the correspondent node.

5. Functional Architecture

 In this section, a functional architecture is developed that
 describes the logical functional entities involved in IP paging and
 the interfaces between them.  Please note that the logical
 architecture makes absolutely no commitment to any physical
 implementation of these functional entities whatsoever.  A physical
 implementation may merge particular functional entities.  For
 example, the Paging Agent, Tracking Agent, and Dormant Monitoring
 Agent may all be merged into one in a particular physical
 implementation.  The purpose of the functional architecture is to
 identify the relevant system interfaces upon which protocol
 development may be required, but not to mandate that protocol
 development will be required on all.

5.1. Functional Entities

 The functional architecture contains the following elements:
    Host - The Host (H) is a standard IP host in the sense of [4]. The
    Host may be connected to a wired IP backbone through a wireless
    link over which IP datagrams are exchanged (mobile usage pattern),
    or it may  be connected directly to a wired IP network, either
    intermittently (nomadic usage pattern) or constantly (wired usage
    pattern).  The Host may support some type of IP mobility protocol
    (for example, mobile IP [2] [3]).  The Host is capable of entering
    dormant mode in order to save power (see [1] for a detailed
    discussion of dormant mode).  The Host also supports a protocol
    allowing the network to awaken it from dormant mode if a packet
    arrives.  This protocol may be a specialized L2 paging channel or
    it may be a time-slotted dormant mode in which the Host
    periodically wakes up and listens to L2 for IP traffic, the
    details of the L2 implementation are not important.  A dormant
    Host is also responsible for determining when its paging area has
    changed and for responding to changes in paging area by directly

Kempf, et al. Informational [Page 9] RFC 3154 Paging Requirements August 2001

    or indirectly informing the Tracking Agent about its location.
    Since routers are presumed not to require dormant mode support, a
    Host is never a router.
    Paging Agent - The Paging Agent is responsible for alerting the
    Host when a packet arrives and the Host is in dormant mode.
    Alerting of the Host proceeds through a protocol that is peculiar
    to the L2 link and to the Host's dormant mode implementation,
    though it may involve IP if supported by the L2.  Additionally,
    the Paging Agent maintains paging areas by periodically wide
    casting information over the Host's link to identify the paging
    area.  The paging area information may be wide cast at L2 or it
    may also involve IP.  Each paging area is served by a unique
    Paging Agent.
    Tracking Agent - The Tracking Agent is responsible for tracking a
    Host's location while it is in dormant mode or active mode, and
    for determining when Host enters inactive mode.  It receives
    updates from a dormant Host when the Host changes paging area.
    When a packet arrives for the Host at the Dormant Monitoring
    Agent, the Tracking Agent is responsible for notifying the Dormant
    Monitoring Agent, upon request, what Paging Agent is in the Host's
    last reported paging area.  There is a one to one mapping between
    a Host and a Tracking Agent.
    Dormant Monitoring Agent - The Dormant Monitoring Agent detects
    the delivery of packets to a Host that is in Dormant Mode (and
    thus does not have an active L2 connection to the Internet).  It
    is the responsibility of the Dormant Monitoring Agent to query the
    Tracking Agent for the last known Paging Agent for the Host, and
    inform the Paging Agent to page the Host.  Once the Paging Agent
    has reported that a routable connection to the Internet exists to
    the Host, the Dormant Monitoring Agent arranges for delivery of
    the packet to the Host.  In addition, the Host or its Tracking
    Agent may select a Dormant Monitoring Agent for a Host when the
    Host enters dormant mode, and periodically as the Host changes
    paging area.

5.2. Interfaces

 The functional architecture generates the following list of
 interfaces.  Note that the interfaces between functional entities
 that are combined into a single network element will require no
 protocol development.
    Host - Paging Agent (H-PA) - The H-PA interface supports the
    following types of traffic:

Kempf, et al. Informational [Page 10] RFC 3154 Paging Requirements August 2001

  1. Wide casting of paging area information from the Paging

Agent.

  1. The Paging Agent alerting the Host when informed by the

Dormant Monitoring Agent that a packet has arrived.

    Host - Tracking Agent (H-TA) - The H-TA interface supports the
    following types of traffic:
  1. The Host informing the Tracking Agent when it has changed

paging area, and, optionally, prior to entering dormant

          mode, in what paging area it is located.
  1. Optionally, the Host informs the Tracking Agent at a planned

transition to inactive mode.

    Dormant Monitoring Agent - Tracking Agent (DMA-TA) - The DMA-TA
    interface supports the following types of traffic:
  1. A report from the Dormant Monitoring Agent to the Tracking

Agent that a packet has arrived for a dormant Host for which

          no route is available.
  1. A report from the Tracking Agent to the Dormant Monitoring

Agent giving the Paging Agent to contact in order to page

          the Host.
  1. A report from the Tracking Agent to the Dormant Monitoring

Agent that a Host has entered inactive mode, if not provided

          directly by the Host
  1. A report from the Tracking Agent to the Dormant Monitoring

Agent that a Host has entered dormant mode, if not provided

          directly by the Host.
    Dormant Monitoring Agent - Paging Agent (DMA-PA) - The DMA-PA
    interface supports the following types of traffic:
  1. A request from the Dormant Monitoring Agent to the Paging

Agent to page a particular Host in dormant mode because a

          packet has arrived for the Host.
  1. Negative response indication from the Paging Agent if the

Host does not respond to a page.

  1. Positive response from the Paging Agent indication if the

Host does respond to a page.

Kempf, et al. Informational [Page 11] RFC 3154 Paging Requirements August 2001

  1. Delivery of the packet to the Host.
    Host - Dormant Monitoring Agent (H-DMA) - The H-DMA interface
    supports the following types of traffic:
  1. The Host registers to the Dormant Monitoring Agent prior to

entering dormant mode, (if needed) with filtering

          information on which broadcast/multicast/anycast packets
          trigger a page.
  1. The Host informs the Dormant Monitoring Agent, when it

directly deregisters from the Dormant Monitoring Agent due

          to a change from dormant mode to active or inactive mode.

5.3. Functional Architecture Diagram

 The functional architecture and interfaces lead to the following
 diagram.
          +------+          H-TA            +----------+
          | Host | <----------------------> | Tracking |
          +------+                          |   Agent  |
              ^ ^                           +----------+
              | |           H-DMA                 ^
              | +------------------------------+  |
              |                                |  | DMA-TA
              |                                |  |
              | H-PA                           |  |
              v                                v  v
          +--------+         DMA-PA         +------------+
          | Paging | <--------------------> |  Dormant   |
          | Agent  |                        | Monitoring |
          +--------+                        |   Agent    |
                                            +------------+
              Figure 1 - Paging Functional Architecture

6. Acknowledgements

 The authors would like to thank Arthur Ross for helpful comments on
 this memo.

Kempf, et al. Informational [Page 12] RFC 3154 Paging Requirements August 2001

7. References

 [1]   Kempf, J., "Dormant Mode Host Alerting ("IP Paging") Problem
       Statement", RFC 3132, June 2001.
 [2]   Perkins, C., ed., "IP Mobility Support", RFC 2002, October,
       1996.
 [3]   Johnson, D., and Perkins, C., "Mobility Support in Ipv6", Work
       in Progress.
 [4]   Braden, R., "Requirements for Internet Hosts - Communication
       Layers", STD 3, RFC 1122, October 1989.
 [5]   Kent, S., and R. Atkinson, "Security Architecture for the
       Internet Protocol", RFC 2401, November 1998.

8. Authors' Addresses

 James Kempf
 Sun Microsystems Laboratories
 901 San Antonio Rd.
 UMTV29-235
 Palo Alto, CA
 95303-4900
 USA
 Phone: +1 650 336 1684
 Fax:   +1 650 691 0893
 EMail: James.Kempf@Sun.COM
 Pars Mutaf
 INRIA Rhone-Alpes
 655 avenue de l'Europe
 38330 Montbonnot Saint-Martin
 FRANCE
 Phone:
 Fax:   +33 4 76 61 52 52
 EMail: pars.mutaf@inria.fr

Kempf, et al. Informational [Page 13] RFC 3154 Paging Requirements August 2001

 Claude Castelluccia
 INRIA Rhone-Alpes
 655 avenue de l'Europe
 38330 Montbonnot Saint-Martin
 FRANCE
 Phone: +33 4 76 61 52 15
 Fax:   +33 4 76 61 52 52
 EMail: claude.castelluccia@inria.fr
 Nobuyasu Nakajima
 Toshiba America Research, Inc.
 P.O. Box 136
 Convent Station, NJ
 07961-0136
 USA
 Phone: +1 973 829 4752
 EMail: nnakajima@tari.toshiba.com
 Yoshihiro Ohba
 Toshiba America Research, Inc.
 P.O. Box 136
 Convent Station, NJ
 07961-0136
 USA
 Phone: +1 973 829 5174
 Fax:   +1 973 829 5601
 EMail: yohba@tari.toshiba.com
 Ramachandran Ramjee
 Bell Labs, Lucent Technologies
 Room 4g-526
 101 Crawfords Corner Road
 Holmdel, NJ
 07733
 USA
 Phone: +1 732 949 3306
 Fax:   +1 732 949 4513
 EMail: ramjee@bell-labs.com

Kempf, et al. Informational [Page 14] RFC 3154 Paging Requirements August 2001

 Yousuf Saifullah
 Nokia Research Center
 6000 Connection Dr.
 Irving, TX
 75039
 USA
 Phone: +1 972 894 6966
 Fax:   +1 972 894 4589
 EMail:  Yousuf.Saifullah@nokia.com
 Behcet Sarikaya
 Alcatel USA, M/S CT02
 1201 Campbell Rd.
 Richardson, TX
 75081-1936
 USA
 Phone: +1 972 996 5075
 Fax:   +1 972 996 5174
 EMail: Behcet.Sarikaya@usa.alcatel.com
 Xiaofeng Xu
 Alcatel USA, M/S CT02
 1201 Campbell Rd.
 Richardson, TX
 75081-1936
 USA
 Phone: +1 972 996 2047
 Fax:     +1 972 996 5174
 Email:  xiaofeng.xu@usa.alcatel.com

Kempf, et al. Informational [Page 15] RFC 3154 Paging Requirements August 2001

9. Full Copyright Statement

 Copyright (C) The Internet Society (2001).  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.

Kempf, et al. Informational [Page 16]

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