Internet Draft                                                    Hamid Syed
draft-ietf-issll-rsvp-cap-03.txt                             Nortel Networks

                                                                   May, 2001

                Capability Negotiation: The RSVP CAP Object

Status of this Memo

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Copyright Notice

   Copyright (C) The Internet Society (2001). All Rights Reserved.

1. Abstract

   The resource reservation protocol [RSVP] is an end-to-end signaling
   protocol and it can be a useful mechanism to carry the upstream node
   or network capabilities/willingness to the downstream network/nodes.

   This draft proposes a capability negotiation object, CAP object, in
   the RSVP PATH message that can be used to convey end host/upstream
   node capabilities to the downstream network/nodes.

2. Introduction

   In today's heterogeneous networking environment, it is important for
   each network node to have a knowledge of its upstream nodes'
   capabilities before it can perform any actions to support the QoS
   requirements of the flows from upstream nodes. The current standards

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   do not provide any way for the end host or upstream network nodes to
   specify their capabilities to the downstream nodes. Without this
   capability, network operators are forced to statically configure the
   behavior of downstream nodes.

   The resource reservation protocol [RSVP] is an end-to-end signaling
   protocol that has already been proposed in different scenarios to
   support end-to-end QoS [INTDIFF]. It can be a useful signaling
   mechanism to carry upstream node capabilities or willingness to
   perform certain functions to the downstream nodes.

   This draft proposes a capability negotiation object, The RSVP CAP
   object, in the RSVP PATH message that can be used to convey end
   host/upstream node capabilities/willingness to the downstream
   network. This is a generic object that can be used to carry any
   meaningful capability information in the RSVP PATH message.

3. 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].

4. Format of CAP Object

   The CAP object has the following format:

              0       |       1       |       2       |       3
      |      Length                   |   C-Num (TBD) |      C-Type=1 |
      |                         CAP field                             |

   The CAP field MUST be defined as a multiple of 32 bits within the
   object. Each capability MUST be defined using one or more bits within
   the CAP field. The associated processing rules specific to each
   capability MUST be explained in a separate section within this
   document. No limitation is imposed on the number of bits in the CAP
   field for the capability representation. Any unused bits in the CAP
   field (i.e. bits that are not assigned to capabilities defined by
   this document) SHOULD be set to zero by upstream originators of the
   CAP object and MUST be ignored by downstream receivers.

5. Capability Definition and Assignment

   This section captures the definition of required capabilities to be
   carried by the capability negotiation (CAP) object in the RSVP PATH
   message. Each subsection is targeted to define one capability, the
   definition of necessary bit assignments and an explanation of the
   processing rules for each capability.

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   Current bit assignments within the CAP field are defined as follows:

       3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0
       1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
      |                            MBZ                              |D|

   0x01 = D_MARK (DS Marking Capability)
   MBZ = not used; must be zero.

5.1 The DS Marking Capability

5.1.1 Description

   The DCLASS object is proposed in [DCLASS] to represent and carry the
   Differentiated Services Code Point (DSCP) to be used by an upstream
   node in an Intserv/Diffserv network [INTDIFF]. A network element in
   the DS network determines the value for DSCP which is carried as a
   DCLASS object in RSVP RESV message to the sender host or upstream
   node. The amount of traffic processing at the downstream network
   node depends on whether or not an upstream node marks the bearer
   packets with the DSCP. An advance knowledge of the upstream node's
   marking capability would allow intelligent decisions to be made at
   the downstream nodes in terms of determining the necessary bearer
   traffic treatment rules to be installed at the network node.

   The RSVP capability negotiation object SHOULD be used to carry the
   upstream node's marking capability to the downstream nodes in the DS
   network. A detailed explanation of how the DS marking capability
   negotiation helps determining the differentiated services packet
   treatment rules should be captured in a separate explanatory draft.

5.1.2 Field Values

   The D_MARK bit in the CAP field MUST be used to indicate the DiffServ
   marking capability/willingness of the upstream nodes as follows.

        If D_MARK bit is set to 0, the sender host/upstream node
        is not able or not willing to mark packets

        If D_MARK bit is set to 1, the sender host/upstream node is
        able and willing to mark packets.

5.1.3 Message Processing Rules PATH Message Generation (Upstream Node)

   An RSVP PATH message is created by an end host or modified by an
   RSVP-aware router as specified in [RSVP] with the following

     1. A capability (CAP) object is created and the D_MARK bit in the
        CAP field is set to indicate the marking capability or
        willingness for packet marking of the network node.

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           D_MARK MUST be set to 1 if the network node is willing and
           capable of packet marking.

           D_MARK MUST be set to 0 if the network node either is not
           capable or it is not willing to mark the packets for the
           requested flow.

     2. The CAP Object is inserted in the RSVP message in the
        appropriate place. PATH Message Reception (Downstream Router)

   RSVP PATH message is processed as specified in [RSVP] with following
   modifications at the downstream RSVP-enabled router in a DS domain.

     1. The router MUST record the status of the D_MARK bit as part of
        the micro-flow PATH state. If a CAP object is not included in
        the PATH message, the router MUST assume the D_MARK value is

     2. The router MUST set the D_MARK bit in the CAP object to reflect
        its own marking capability for the downstream nodes. RESV Message Reception (Downstream Router)

   RSVP RESV message is processed as specified in [RSVP] with following
   modifications at the downstream RSVP-enabled router in a DS domain.

     1. The router MUST check the recorded PATH state for the
         micro-flow and install the necessary treatment rules required
         to handle the traffic in a DS network.

     2. If the upstream node has specified its packet marking
         willingness by setting the D_MARK bit, the router MUST install
         configuration rules required for  receiving and forwarding DS
         marked packets from the upstream node. The router MAY insert a
         DCLASS object into the RESV message to indicate the DSCP to be
         used by the upstream node for this micro-flow.

     3. If the upstream node is not willing or capable of packet
         marking, the router MUST install the packet classification,
         marking and packet forwarding rules for the downstream traffic.

     4. If the router is not aware of the rules, it SHOULD seek the
         policy rules from the domain policy server.

6. IANA Considerations

   The format of CAP object requires a class number (C-Num) in RSVP
   message that MUST be supplied through IANA.

7. References

   [INTDIFF], Bernet, Y., Yavatkar, R., Ford, P., Baker, F., Zhang, L.,
   Speer, M., Braden, R., Davie, B., Wroclawski, J., "Integrated
   Services Operation over Diffserv Networks", RFC 2998, November 2000

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   [RSVP] Braden, R. ed., "Resource ReSerVation Protocol (RSVP) -
   Functional Specification.", IETF RFC 2205, Sep. 1997.

   [RFC-2119] S. Bradner, "keywords for use in RFCs to Indicate
   Requirement Levels", RFC 2119 (BCP), IETF, March 1997.

   [DCLASS] Bernet, Y., "Format of the RSVP DCLASS Object", RFC 2996,
   November 2000.

8. Acknowledgments

   Thanks to Yoram Bernet and other ISSLL WG members for providing
   useful input to make this one happen. Special thanks to Bill Gage for
   reviewing the draft

9. Author's Address

   Syed, Hamid
   Nortel Networks
   100 - Constellation Crescent,
   Nepean, ON K2G 6J8
   Phone: (613) 763-6553
   Email: hmsyed@nortelnetworks.com

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   This document and the information contained herein is provided on an

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