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Versions: 00 01 02 03 04 05                                             
Network Working Group                                       G. Cristallo
Internet Draft                                                   Alcatel
Document: draft-jacquenet-qos-nlri-04.txt                   C. Jacquenet
Category: Experimental                                France Telecom R&D
Expires September 2002                                        March 2002

   Providing Quality of Service Indication by the BGP-4 Protocol: the
                           QOS_NLRI attribute

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC 2026 [1].

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that other
   groups may also distribute working documents as Internet-Drafts.
   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress".

   The list of current Internet-Drafts can be accessed at

   The list of Internet-Draft Shadow Directories can be accessed at

   NOTE: a PDF version of this document (that includes the figures
   mentioned in section 7) can be accessed at http://www.ist-


   This draft specifies an additional BGP4 (Border Gateway Protocol,
   version 4, [2]) attribute, named the "QOS_NLRI" attribute, which aims
   at providing QoS (Quality of Service)-related information associated
   to the NLRI (Network Layer Reachability Information) information
   conveyed in a BGP UPDATE message.

1. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [3].

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2. Introduction

   Providing end-to-end quality of service is probably one of the most
   important challenges of the Internet, not only because of the massive
   development of value-added IP service offerings, but also because of
   the various QoS policies that are currently deployed and enforced
   within an autonomous system, and which may well differ from one AS
   (Autonomous System) to another.

   For almost the last decade, value-added IP service offerings have
   been deployed over the Internet, thus yielding a dramatic development
   of the specification effort, as far as quality of service in IP
   networks is concerned. Nevertheless, providing end-to-end quality of
   service by crossing administrative domains still remains an issue,
   mainly because:

   - QoS policies may dramatically differ from one service provider to
   - The enforcement of a specific QoS policy may also differ from one
     domain to another, although the definition of a set of basic and
     common quality of service indicators may be shared between the
     service providers.

   Activate the BGP4 protocol for exchanging reachability information
   between autonomous systems has been a must for many years, and, from
   this standpoint, the BGP4 protocol is one of the key components for
   the enforcement of end-to-end QoS policies.

   Therefore, exchanging QoS-related information as well as reachability
   information in a given BGP UPDATE message appears to be helpful in
   enforcing an end-to-end QoS policy.

   This draft aims at specifying a new BGP4 attribute, the QOS_NLRI
   attribute, which will convey QoS-related information associated to
   the routes described in the corresponding NLRI field of the

   This document is organized into the following sections:

   - Section 3 identifies the changes that have been made in the
     document since the last version,

   - Section 4 describes the basic requirements that motivate the
     approach, based upon the use of an additional BGP4 attribute,

   - Section 5 describes the attribute and its mode of operation,

   - Section 6 elaborates on the use of the capabilities advertisement
     feature of the BGP4 protocol,

   - Section 7 depicts the preliminary results of an ongoing simulation

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   - Finally, sections 8 and 9 introduce IANA and some security
     considerations, respectively.

3. Changes since the last version of this draft

   The current version of this draft reflects the following changes:

   - Slight re-ordering of the beginning of the document,

   - Introduction of a Requirements section (section 4),

   - Developed the simulation results section (section 7),

   - The References section has been updated,

   - Correction of remaining typos.

4. Basic requirements

   The choice of using the BGP4 protocol for exchanging QoS information
   between domains is not only motivated by the fact this is currently
   the only inter-domain (routing) protocol activated in the Internet,
   but also because the manipulation of attributes is a powerful means
   for service providers to announce QoS information with the desired
   level of precision.

   The approach presented in this draft has identified the following

   - Keep the approach scalable. The scalability of the approach can be
     defined in many ways that include the convergence time to reach a
     consistent view of the network connectivity, the number of route
     entries that will have to be maintained by a BGP peer, the
     dynamics of the route announcement mechanism (e.g., how frequently
     and under which conditions should an UPDATE message containing QoS
     information be sent?), etc.

   - Keep the BGP4 protocol operation unchanged. The introduction of a
     new attribute should not affect the way the protocol operates, but
     the information contained in this attribute may very well
     influence the BGP route selection process.

   - Allow for a smooth migration. The use of a specific BGP attribute
     to convey QoS information should not constrain network operators
     to migrate the whole installed base at once, but rather help them
     in gradually deploying the QoS information processing capability.

5. The QOS_NLRI attribute (Type Code XY*)

   (*): "XY" is subject to the IANA considerations section of this

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   The QOS_NLRI attribute is an optional transitive attribute that can
   be used for the following purposes:

   (a) To advertise a QoS route to a peer. A QoS route is a route that
       meets one or a set of QoS requirement(s) to reach a given (set
       of) destination prefixes (see [4], for example). Such QoS
       requirements can be expressed in terms of minimum one-way delay
       ([5]) to reach a destination, the experienced delay variation
       for IP datagrams that are destined to a given destination prefix
       ([6]), the loss rate experienced along the path to reach a
       destination, and/or the identification of the traffic that is
       expected to use this specific route (identification means for
       such traffic include DSCP (DiffServ Code Point, [7]) marking).
       These QoS requirements can be used as an input for the route
       calculation process embedded in the BGP peers, e.g. thanks to
       the activation of a signaling protocol, such as RSVP (Resource
       ReSerVation Protocol, [8]),

   (b) To provide QoS information along with the NLRI information in a
       single BGP UPDATE message. It is assumed that this QoS
       information will be related to the route (or set of routes)
       described in the NLRI field of the attribute.

  From a service provider's perspective, the choice of defining the
  QOS_NLRI attribute as an optional transitive attribute is basically
  motivated by the fact that this kind of attribute allows for gradual
  deployment of QoS extensions to BGP4: not all the BGP peers are
  supposed to be updated accordingly, while partial deployment of such
  QoS extensions can already provide an added value.

  This draft makes no specific assumption about the means to actually
  value this attribute, since this is mostly a matter of
  implementation, but the reader is kindly suggested to have a look on
  document [9], as an example of a means to feed the BGP peer with the
  appropriate information. The QOS_NLRI attribute is encoded as

            | QoS Information Code (1 octet)                          |
            | QoS Information Sub-code (1 octet)                      |
            | QoS Information Value (2 octets)                        |
            | QoS Information Origin (1 octet)                        |
            | Address Family Identifier (2 octets)                    |
            | Subsequent Address Family Identifier (1 octet)          |
            | Network Address of Next Hop (4 octets)                  |

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            | Network Layer Reachability Information (variable)       |

   The use and meaning of the fields of the QOS_NLRI attribute are
   defined as follows:

   -   QoS Information Code:

       This field carries the type of the QOS information. The
       following types have been identified so far:

   (0) Reserved
   (1) Packet rate, i.e. the number of IP datagrams that can be
       transmitted (or have been lost) per unit of time, this number
       being characterized by the elaboration provided in the QoS
       Information Sub-code (see below)
   (2) One-way delay, as defined in [5]
   (3) Inter-packet delay variation, as defined in [6]
   (4) PHB Identifier, as defined in [10]

   -   QoS Information Sub-code:

       This field carries the sub-type of the QoS information. The
       following sub-types have been identified so far:

   (0) None (i.e. no sub-type, or sub-type unavailable, or unknown sub-
   (1) Reserved rate
   (2) Available rate
   (3) Loss rate
   (4) Minimum one-way delay
   (5) Maximum one-way delay
   (6) Average one-way delay

   The instantiation of this sub-code field MUST be compatible with the
   value conveyed in the QoS Information code field, as stated in the
   following table (the rows represent the QoS Information Code possible
   values, the columns represent the QoS Information Sub-code values
   identified so far, while the "X" sign indicates incompatibility).

            |    |  0 |  1 |  2 |  3 |  4 |  5 |  6 |
            |  0 |    |    |    |    |    |    |    |
            |  1 |    |    |    |    |  X |  X |  X |
            |  2 |    |  X |  X |  X |    |    |    |
            |  3 |    |  X |  X |  X |  X |  X |  X |

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            |  4 |    |  X |  X |  X |  X |  X |  X |

   -   QoS Information Value:

       This field indicates the value of the QoS information. The
       corresponding units obviously depend on the instantiation of the
       QoS Information Code. Namely, if:

   (a) QoS Information Code field is "0", no unit specified,
   (b) QoS Information Code field is "1", unit is kilobits per second
       (kbps), and the rate encoding rule is composed of a 3-bit
       exponent (with an assumed base of 8) followed by a 13-bit
       mantissa, as depicted in the figure below:

                             0      8       16
                             |       |       |
                             |Exp| Mantissa  |

       This encoding scheme advertises a numeric value that is (2^16 -1
       - exponential encoding of the considered rate), as depicted in
   (c) QoS Information Code field is "2", unit is milliseconds,
   (d) QoS Information Code field is "3", unit is milliseconds,
   (e) QoS Information Code field is "4", no unit specified.

   -   QoS Information Origin:

       This field provides indication on the origin of the path
       information, as defined in section 4.3.of [2].

   -   Address Family Identifier (AFI):

       This field carries the identity of the Network Layer protocol
       associated with the Network Address that follows. Presently
       defined values for this field are specified in [12] (see the
       Address Family Numbers section of this reference document).

   -   Subsequent Address Family Identifier (SAFI):

       This field provides additional information about the type of the
       NLRI carried in the QOS_NLRI attribute.

   -   Network Address of Next Hop:

       This field contains the IPv4 Network Address of the next router
       on the path to the destination prefix, (reasonably) assuming
       that such routers can at least be addressed according to the
       IPv4 formalism.

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   -   Network Layer Reachability Information:

       This variable length field lists the NLRI information for the
       feasible routes that are being advertised by this attribute. The
       next hop information carried in the QOS_NLRI path attribute
       defines the Network Layer address of the border router that
       should be used as the next hop to the destinations listed in the
       QOS_NLRI attribute in the UPDATE message.

   When advertising a QOS_NLRI attribute to an external peer, a router
   may use one of its own interface addresses in the next hop component
   of the attribute, given the external peer to which the route is being
   advertised shares a common subnet with the next hop address.  This is
   known as a "first party" next hop information.

   A BGP speaker can advertise to an external peer an interface of any
   internal peer router in the next hop component, provided the external
   peer to which the route is being advertised shares a common subnet
   with the next hop address.  This is known as a "third party" next hop

   A BGP speaker can advertise any external peer router in the next hop
   component, provided that the Network Layer address of this border
   router was learned from an external peer, and the external peer to
   which the route is being advertised shares a common subnet with the
   next hop address. This is a second form of "third party" next hop

   Normally the next hop information is chosen so that the shortest
   available path will be taken. A BGP speaker must be able to support
   disabling advertisement of third party next hop information to handle
   imperfectly bridged media or for reasons of policy.

   A BGP speaker must never advertise an address of a peer to that peer
   as a next hop, for a route that the speaker is originating.  A BGP
   speaker must never install a route with itself as the next hop.

   When a BGP speaker advertises the route to an internal peer, the
   advertising speaker should not modify the next hop information
   associated with the route. When a BGP speaker receives the route via
   an internal link, it may forward packets to the next hop address if
   the address contained in the attribute is on a common subnet with the
   local and remote BGP speakers.

   A BGP UPDATE message that carries the QOS_NLRI MUST also carry the
   ORIGIN and the AS_PATH attributes (both in eBGP and in iBGP
   exchanges). Moreover, in IBGP exchanges such a message MUST also
   carry the LOCAL_PREF attribute. If such a message is received from an
   external peer, the local system shall check whether the leftmost AS
   in the AS_PATH attribute is equal to the autonomous system number of
   the peer than sent the message. If that is not the case, the local

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   system shall send the NOTIFICATION message with Error Code UPDATE
   Message Error, and the Error Sub-code set to Malformed AS_PATH.

   An UPDATE message that carries no NLRI, other than the one encoded in
   the QOS_NLRI attribute, should not carry the NEXT_HOP attribute. If
   such a message contains the NEXT_HOP attribute, the BGP speaker that
   receives the message should ignore this attribute.

6. Use of Capabilities Advertisement with BGP-4

   A BGP speaker that uses the QOS_NLRI attribute SHOULD use the
   Capabilities Advertisement procedures, as defined in [13], so that it
   might be able to determine if it can use such an attribute with a
   particular peer.

   The fields in the Capabilities Optional Parameter are defined as

   -  The Capability Code field is set to N (127 < N < 256, when
      considering the "Private Use" range, as specified in [14]), while
      the Capability Length field is set to "1".

   -  The Capability Value field is a one-octet field, which contains
      the Type Code of the QOS_NLRI attribute, as defined in the
      introduction of section 4 of the present draft.

7. Preliminary simulation results

7.1. A phased approach

   The simulation work that has begun within the context of the TEQUILA
   project (see [4]) basically aims at qualifying the scalability of the
   usage of the QOS_NLRI attribute for propagating QoS-related
   information between domains. This work also aims at quantifying the
   added value provided by the QoS extensions to BGP4, as a function of
   the percentage of the accordingly updated BGP peers.

   This effort has also been launched to focus on the impact on the
   stability of the BGP routes, by defining a set of basic engineering
   rules for the introduction of new QoS information, as well as design
   considerations for the calculation of "QoS routes".

   This ongoing development effort is organized into a step-by-step
   approach, which consists in the following phases:

     1. Model an IP network composed of several autonomous systems.
        Since this simulation effort is primarily focused on the
        qualification of the scalability related to the use of the
        QOS_NLRI attribute for exchanging QoS-related information
        between domains, it has been decided that the internal
        architecture of such domains be kept very simple, i.e. without
        any specific IGP interaction,

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     2. Within this IP network, there are BGP peers that are QOS_NLRI
        aware, i.e. they have the ability to process the information
        conveyed in the attribute, while the other routers do not: these
        routers do not recognize the QOS_NLRI attribute by definition,
        and they will forward the information to other peers, by setting
        the Partial bit in the attribute, meaning that the information
        conveyed in the message is incomplete. This approach allows to
        elaborate on the added value introduced by a gradual deployment
        of the QoS extensions to BGP4,

     3. As far as QOS_NLRI aware BGP peers are concerned, they will
        process the information contained in the QOS_NLRI attribute to
        possibly influence the route decision process, thus yielding the
        selection (and the installation) of distinct routes towards a
        same destination prefix, depending on the QoS-related
        information conveyed in the QOS_NLRI attribute. From this
        implementation perspective, the BGP routing tables have been
        modeled so that they contain a "sub-section" where QOS_NLRI-
        capable peers will store the information conveyed in the

     4. Modify the BGP route decision process: at this stage of the
        simulation, the modified decision process relies upon the one-
        way delay information (which corresponds to the QoS Information
        Code field of the attribute valued at "2"), and it also takes
        into account the value of the Partial bit of the attribute.

   Once the creation of these components of the IP network has been
   completed (together with the modification of the BGP route selection
   process), the behavior of a QOS_NLRI-capable BGP peer is as follows:

   Upon receipt of a BGP UPDATE message that contains the QOS_NLRI
   attribute, the router will first check if the corresponding route is
   already stored in its local RIB, according to the value of the one-
   way delay information contained in both QoS Information Code and Sub-
   code fields of the attribute.

   If not, the BGP peer will install the route in its local RIB.
   Otherwise (i.e. an equivalent route already exists in its database),
   the BGP peer will select the best of both routes according to the
   following criteria:

   -   If both routes are said to be either incomplete (Partial bit has
       been set) or complete (Partial bit is unset), the route with the
       lowest delay will be selected,

   -   Otherwise, a route with the Partial bit unset is always
       preferred over any other route, even if this (complete) route
       reflects a higher transit delay.

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   If ever both Partial bit and transit delay information are not
  sufficient to make a decision, the standard BGP decision process
  (according to the breaking ties mechanism depicted in [2]) is

7.2. A case study

   As stated in the previous section 7.1, the current status of the
   simulation work basically relies upon the one-way transit delay
   information only, as well as the complete/incomplete indication of
   the Partial bit conveyed in the QOS_NLRI attribute.

   The following figures depict the actual processing of the QoS-related
   information conveyed in the QOS_NLRI attribute, depending on whether
   the peer is QOS_NRLI-aware or not.

                       [- Figure 1: a case study. -]

   Figure 1 depicts the IP network that has been modelled, while figure
   2 depicts the propagation of a BGP UPDATE message that contains the
   QOS_NLRI attribute, in the case where the contents of the attribute
   are changed, because of complete/incomplete conditions depicted by
   the Partial bit of the QOS_NLRI attribute.

    [- Figure 2: propagation of one-way delay information via BGP4. -]

   Router S in figure 2 is a QOS_NRLI-capable speaker. It takes 20
   milliseconds to node S to reach network this information
   will be conveyed in a QOS_NLRI attribute that will be sent by node S
   in a BGP UPDATE message with the Partial bit of the QOS_NLRI
   attribute unset.

   Router A is another QOS_NLRI BGP peer, and it takes 3 milliseconds
   for A to reach router S. Node A will update the QoS-related
   information of a QOS_NLRI attribute, indicating that, to reach
   network, it takes 23 milliseconds. Router A will install
   this new route in its database, and will propagate the corresponding
   UPDATE message to its peers.

   On the other hand, router B is not capable of processing the
   information conveyed in the QOS_NLRI attribute, and it will therefore
   set the Partial bit of the QOS_NLRI attribute in the corresponding
   UPDATE message, leaving the one-way delay information detailed in
   both QoS Information Code and Sub-code unchanged.

   Upon receipt of the UPDATE message sent by router A, router E will
   update the one-way delay information since it is a QOS_NRLI-capable
   peer. Finally, router D receives the UPDATE message, and selects a
   route  with  a  40  milliseconds  one-way  delay  to  reach  network, as depicted in figure 3.

           [- Figure 3: selecting QoS routes across domains. -]

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   This simulation result shows that the selection of a delay-based
   route over a BGP route (as depicted in [2]) may not yield an optimal
   decision. In the above example, the 40 ms-route goes through routers
   D-E-A-S, while a "truly optimal" BGP route would be through routers
   D-E-F-A-S, hence a 38 ms-route. This is because of a BGP4 rule that
   does not allow router F to send an UPDATE message towards router E,
   because router F received the UPDATE message from router A thanks to
   the iBGP connection it has established with A.

   These basic observations confirm that the enforcement of a QoS policy
   between domains by using the BGP4 protocol is obviously conditioned
   by the BGP4 routing policies that are enforced within each domain.

7.3. Preliminary results

   The following table reflects the first results obtained from a
   simulation network composed of 9 autonomous systems and 20 BGP peers.
   The numbers contained in the columns reflect the percentage of
   serviced requirements, where the requirements are expressed in terms
   of delay.

   Three parameters have been taken into account:

   -  The percentage of BGP peers that have the ability to process the
      information conveyed in the QOS_NLRI attribute (denoted as "x% Q-
      BGP" in the following table),

   -  The transit delays "observed" (and artificially simulated) on
      each transmission link: the higher the delays, the lower the
      percentage of serviced QoS requirements,

   -  The QoS requirements themselves, expressed in terms of delay: as
      such, the strongest requirements (i.e. the lowest delays) have
      less chance to be satisfied.

            | Delay | 0% Q-BGP | 50% Q-BGP | 100% Q-BGP |
            |  3    |    11    |    8,3    |    11      |
            |  5    |    30,5  |    30,5   |    36,1    |
            |  6    |    40    |    47,2   |    55,5    |
            |  7    |    47    |    59,7   |    72,2    |
            |  8    |    62,5  |    79     |    91,6    |
            |  9    |    63    |    84,7   |    97,2    |
            |  10   |    70,8  |    90,2   |    98,6    |

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            |  11   |    76,3  |    93     |    98,6    |
            |  12   |    86,1  |    97,2   |    100     |
            |  13   |    88,8  |    98,6   |    100     |
            |  14   |    94,4  |    100    |    100     |
            |  15   |    94,4  |    100    |    100     |
            |  16   |    94,4  |    100    |    100     |
            |  17   |    97,2  |    100    |    100     |
            |  18   |    98,6  |    100    |    100     |
            |  19   |    98,6  |    100    |    100     |
            |  20   |    98,6  |    100    |    100     |
            |  21   |    98,6  |    100    |    100     |
            |  22   |    100   |    100    |    100     |

   While this table demonstrates the technical feasibility of the
   approach (and how the use of the QOS_NLRI attribute can improve the
   percentage of serviced QoS requirements), the results presented here
   remain obviously preliminary, as discussed in the next section.

7.4. Next steps

   The above-mentioned simulation effort will be pursued in order to
   better qualify the interest of using the BGP4 protocol to convey QoS-
   related information between domains, from a scalability perspective,
   i.e. the increase of BGP traffic vs. the stability of the network.

   The stability of the IP network is probably one of the most important
   aspects, since QoS-related information is subject to very dynamic
   changes, thus yielding non-negligible risks of flapping.

   It is therefore expected that the upcoming versions of this draft
   will reflect the progress of this simulation work, which will take
   into account other types of QoS information, among other tracks of

8. IANA Considerations

   Section 5 of this draft documents an optional transitive BGP-4
   attribute named "QOS_NLRI" whose type value will be assigned by IANA.

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   Section 6 of this draft also documents a Capability Code whose value
   should be assigned by IANA.

9. Security Considerations

   This additional BGP-4 attribute specification does not change the
   underlying security issues inherent in the existing BGP-4 protocol
   specification [15].

10. References

   [1]  Bradner, S., "The Internet Standards Process -- Revision 3", BCP
      9, RFC 2026, October 1996.

   [2]  Rekhter Y., Li T., "A Border Gateway Protocol 4 (BGP-4)", RFC
      1771, March 1995.

   [3]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997.

   [4]  Goderis, D., T'Joens, Y., Jacquenet, C., Memenios, G., Pavlou,
      G., Egan, R., Griffin, D., Georgatsos, P., Georgiadis, L.,
      "Specification of a Service Level Specification (SLS) Template",
      draft-tequila-sls-01.txt, Work in Progress, June 2001. Check
      http://www.ist-tequila.org for additional information.

   [5]  Almes, G., Kalidindi, S., "A One-Way-Delay Metric for IPPM", RFC
      2679, September 1999.

   [6]  Demichelis, C., Chimento, P., "IP Packet Delay Variation Metric
      for IPPM", draft-ietf-ippm-ipdv-08.txt, Work in Progress, November

   [7]  Nichols, K., Blake, S., Baker, F., Black, D., "Definition of the
      Differentiated Services Field (DS Field) in the IPv4 and IPv6
      Headers", RFC 2474, December 1998.

   [8]  Braden, R., et al., "Resource ReSerVation Protocol (RSVP)-
      Version 1 Functional Specification", RFC 2205, September 1997.

   [9]  Jacquenet, C., "A COPS client-type for IP traffic engineering",
      draft-jacquenet-ip-te-cops-02.txt, Work in Progress, June 2001.

   [10] Black, D., Brim, S., Carpenter, B., Le Faucheur, F., "Per Hop
      Behavior Identification Codes", RFC 3140, June 2001.

   [11] Apostolopoulos, G. et al, "QoS Routing Mechanisms and OSPF
      Extensions", RFC 2676, August 1999.

   [12] Reynolds, J., Postel, J., "ASSIGNED NUMBERS", RFC 1700, October

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   [13] Chandra, R., Scudder, J., "Capabilities Advertisement with BGP-
      4", RFC 2842, May 2000.

   [14] Narten, T., Alvestrand, H., "Guidelines for Writing an IANA
      Considerations Section in RFCs", RFC 2434, October 1998.

   [15] Heffernan, A., "Protection of BGP sessions via the TCP MD5
      Signature Option", RFC 2385, August 1998.

11. Acknowledgments

   Part of this work is funded by the European Commission, within the
   context of the TEQUILA (Traffic Engineering for Quality of Service in
   the Internet At Large Scale, [4]) project, which is itself part of
   the IST (Information Society Technologies) research program.

   The author would also like to thank all the partners of the TEQUILA
   project for the fruitful discussions that have been conducted within
   the context of the traffic engineering specification effort of the
   project, as well as O. Bonaventure and B. Carpenter for their
   valuable input.

12. Authors' Addresses

   Geoffrey Cristallo
   Francis Wellesplein, 1
   2018 Antwerp
   Phone: +32 (0)3 240 7890
   E-Mail: geoffrey.cristallo@alcatel.be

   Christian Jacquenet
   France Telecom R & D
   42, rue des Coutures
   BP 6243
   14066 Caen Cedex 4
   Phone: +33 2 31 75 94 28
   Email: christian.jacquenet@rd.francetelecom.com

13. Full Copyright Statement

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   or assist its implementation may be prepared, copied, published and
   distributed, in whole or in part, without restriction of any kind,

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   provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
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   the copyright notice or references to the Internet Society or other
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   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

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