draft-ietf-issll-rsvp-cap-01.txt					  draft-ietf-issll-rsvp-cap-02.txt

Internet Draft                                                 Syed, Hamid,
draft-ietf-issll-rsvp-cap-01.txt Hamid
draft-ietf-issll-rsvp-cap-02.txt			   Nortel Networks

                                			    November, 2000

                                			    February, 2001

		Capability Negotiation: The RSVP CAP Object

Status of this Memo

   This document is an Internet-Draft and is in full conformance with all
   provisions of Section 10 of RFC2026.

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   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2000). (2001). All Rights Reserved.

1. Abstract

   The DCLASS object resource reservation protocol [RSVP] is proposed in [DCLASS] to represent an end-to-end signaling
   protocol and it can be a useful mechanism to carry
   Differentiated Services Code Points (DSCPs) within the upstream node or
   network capabilities/willingness to the downstream network/nodes.

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

2. Introduction

   In today's heterogenous networking environment, it is important for each
   network to carry DSCP information
   between have a DS network and knowledge of its upstream nodes that may wish nodes/network capabilities
   before it can perform any actions to mark packets
   with DSCP values. A network element in support the QoS requirements of the

   draft-ietf-issll-rsvp-cap-02.txt	                     February, 2001

   flows from upstream networks. Such an advance information would help the DS
   network determines operator to configure the
   value for DSCP which is further carried as a DCLASS object in RSVP
   RESV message network according to the sender host.

   There may be situations where expected
   nature of traffic that the sender host is not capable or may
   not wish network devices have to mark the packets. Currently, there is no process and route.
   The current standards does not provide any way for to the end host or
   network devices to specify their capabilities to the downstream nodes.
   The resource reservation protocol [RSVP] is an end-to-end signaling
   protocol and has already been proposed in different scenarios to support
   end-to-end QoS [INTDIFF]. It can be a useful signaling mechanism to
   carry the upstream node/network capabilities or willingness to the
   downstream network or nodes.

   This draft proposes a capability object (CAP object) negotiation object, The RSVP CAP
   object, in the RSVP PATH message that can be used to convey end
   host/upstream node
   capabilities capabilities/willingness to the downstream network. It also defines one bit in the
   CAP field of the CAP object to convey the host/upstream node's

   draft-ietf-issll-rsvp-cap-01.txt	                   November, 2000

   marking capability/willingness for accepting
   This is a DCLASS generic object from the
   downstream network and marking that can be used to carry any meaningful
   capability information in the downstream packets.

2. Introduction

   The mechanics of using RSVP [RSVP] signalling and the DCLASS object
   for requesting PATH message.

3. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and applying the QoS "OPTIONAL" in a differentiated services [DS]
   network is this
   document are to be interpreted as described fully in [INTDIFF]. It assumes an architecture
   with RSVP senders and receivers and a differentiated services network
   somewhere between the sender and the receiver. At least one RSVP aware
   network element resides in the diff-serv network. This network element
   interacts with RSVP messages arriving from outside the DS network.

   The principle use of the DCLASS object is to carry DSCP information
   between a DS network and upstream nodes that may wish to mark packets
   with DSCP values. A network element in the DS network determines the
   value for DSCP which is further carried as a DCLASS object in RSVP
   RESV message to the sender host. If the network element determines
   that the request represented by the PATH and RESV messages is
   admissible to the diff-serv network, a desision is made to mark the
   arriving data packets for this traffic using MF classification, or
   to request upstream marking of packets with the appropriate DSCPs.
   If the network element decides the packets to be marked at the sender
   host for the data traffic, it adds a DCLASS object in the RSVP RESV
   message to the host. The use and format of DCLASS object is fully
   specified in [DCLASS].

   There may be situations where the sender host is not capable or may
   not wish to mark the packets. In the current definition of DCLASS
   object, the network edge device inserts the DCLASS object in the RSVP
   RESV message without having any prior knowledge of the host capability
   whether or not the host can make use of this object. This is one
   example where the network element needs to know the host capabilities
   before making a policy decision. Moreover, the definition of DCLASS
   object allows any DS domain to supply DCLASS object on a flow to the
   upstream DS domains. A prior knowledge of the upstream DS domain's
   marking capability could be useful for the downstream DS domain. There
   could be other scenerios where an advance knowledge of the host or a
   upstream node's capability  may help the network to provide better
   policy decisions to the end host. Currently, there is no way for the
   host or network devices to specify their capabilities.

   The decision where the data packets should be marked can be made at the
   DS network nodes assuming that the network edge devices have a prior
   knowledge of the marking capability of the upstream domains.
   Section 3 of this draft describes two scenarios to explain the use of
   CAP object in RSVP PATH message.

3. Capability Negotiation

   The capability object called 'CAP' object can be used as a mechanism
   for conveying node capabilities or willingness in RSVP messages. As an
   example, we will focus on the marking capability of nodes throughout
   this document and define a single bit for host marking information to
   be carried in the CAP field inside the CAP object of RSVP PATH message.

   draft-ietf-issll-rsvp-cap-01.txt	                   November, 2000

   However, the CAP is a generic object that can be used to carry any other
   meaningful capability information in the RSVP PATH message. To explain
   the use of CAP object in RSVP PATH message, we will describe two
   scenarios

       - Host-Edge router interaction
       - Border Router-Border Router interaction

   It should be noted that how and when the packets will be marked is a
   decision governed by the network policies. The network policy domain
   may or may not trust the end host marking. Hence, even though the network
   may have supplied the DCLASS object to the end host on request (via CAP)
   it may overwrite the marking based on the domain policy.

3.1 Host-Edge Router Capbility Negotiation

   The advance knowledge of the end host's capabilities may help the
   network edge devices to make policy decisions on end host's requests.
   These capabilities can be indicated in the RSVP PATH message to the
   downstream edge devices.

   The end hosts can be classiffied in two categories: Those capable of
   marking downstream packets and decide to do so. The other category of
   hosts either do not have the capability to mark packets or they decide
   not to mark packets. In either case, the network element needs to know
   the host packet marking capability/willingness. This information can
   help the network element to decide whether or not a DCLASS object must
   be added in a RSVP message for the flow. One way to convey the host
   capability/willingness to the network is to use the RSVP PATH message.
   We give examples here to explain the scenarios.

   If the sender host is ready to mark the downstream traffic (based on the
   DCLASS provided by the network element), it sets the marking bit of the
   CAP field inside the CAP object of the RSVP PATH message. On receiving
   the RSVP message, the network element at the DS edge records the host
   marking capability as the PATH state. It then resets the marking bit and
   sends the RSVP message to the downstream nodes. The treatment of the CAP
   object at the downstream nodes will be explained in next section. For now,
   consider the RESV message comes back to the edge device, it performs the
   necessary admission control. If the network element determines that the
   request represented by the PATH and RESV messages is admissible to the
   diff-serv network, it adds a DCLASS object after consulting the recorded
   state. It may decide to overwrite any DCLASS object inserted by the
   an downstream node/domain based on its own domain policies. This is
   exactly how the DCLASS object is defined.

   Another example could be the end host that is not capable of downstream
   packet marking. This either will not include a CAP object or the host
   will reset the marking bit of the CAP object as an indication of his
   unwillingness of packet marking. The network edge router will then know
   that the upstream node/end host does not require a DCLASS object. The
   edge router, in this case, would be responsible for marking the downstream
   packets from the end host.

   draft-ietf-issll-rsvp-cap-01.txt	                   November, 2000

3.2 Boundry router-Boundry Router Interaction

   The CAP object could be carried in the PATH message end-to-end. The RSVP
   PATH message is generated by the end host. The network edge router 'A'
   of the DS domain processes the message, resets the marking bit of the
   CAP object (if it comes as set from the host) and passes the PATH message
   to the next RSVP Hop. For a DS domain, the boundray router 'B' of the
   access/stub network receives the RSVP PATH message as next RSVP enabled
   node (Figure 1). It may set the marking bit again to advertise the marking
   capability of its own domain. The decision must be governed by the domain
   policy. The ingress boundary router 'C' of the downstream domain receives
   the CAP object with the marking bit set providing an indication of the
   marking capability of the upstream node/domain. It again stores this
   information as the PATH state, resets the marking bit and passes it to
   the downstream RSVP enabled network element. The boundary router 'D' of
   this domain may decide to set the marking bit again based on the domain
   policy. The PATH message may pass through more domains like this until
   it is received by the host. The RSVP RESV message is then generated and
   passed through the same route. The RSVP message arrives at the the
   router 'C' and it may contain a DCLASS object provided by an downstream
   node/domain. The PATH state of router 'C' indicates that the upstream
   node/domain is capable of packet marking and a DCLASS object is to be
   passed back. The domain policy/admission control decisions of router 'C'
   may not allow the router to use the same DCLASS value as it received
   from the downstream. So it may decide to overwrite the DCLASS value. The
   edge router 'A' may also decide to remark the DCLASS value in the RESV
   message following its admission control outcome and knowing the end
   host's willingness for packet marking. Finally, the end host receives
   the DCLASS value in RESV message and it may start marking the downstream
   packets with the appropriate DSCP.

   Once again, It should be noted that how and when the packets will be
   marked is a decision governed by the network policies. The network
   policy domain may or may not trust the end host marking. Hence, even
   though the network may have supplied the DCLASS object to the end host
   on request (via CAP) it may overwrite the marking based on the domain
   policy.

                 +----------+         +-----------+
                 |DS domain |         |DS domain  |
                 |     1    |         |     2     |
    +----+     +----+     +----+    +----+      +----+         +----+
    |Host|-----| A  |     | B  |----| C  |      | D  |---''''''|Host|
    +----+     +----+     +----+    +----+      +----+         +----+
                 |          |         |           |
                 |          |         |           |
                 +----------+         +-----------+

			      Figure 1 [RFC-2119].

4. Format of CAP Object

   The CAP object has the following format:

              0       |       1       |       2       |       3
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Length                   |   C-Num (226) (TBD) |      C-Type=1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 	CAP field		              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   draft-ietf-issll-rsvp-cap-01.txt	                   November, 2000

   CAP field:

	0x01: D_MARK

   The host marking capability/willingness identifier.
		If D_MARK bit CAP field is reset, defined with full 32 bits in the sender host/upstream node
                is not able to mark packets
		If D_MARK object. Each bit is set, in
   the sender host/upstream node is
                able/willing to mark packets

   Note: D_MARK field can be used for one specific capability representation.

5. Message Processing Rules

5.1 Message Generation (RSVP Host)

   An RSVP PATH message is a bit created as specified in [RSVP] with following
   modifications

     1. A capability (CAP) object is created and the CAP (capbility) field.

5. Deployment Scenarios

   There are a number field is set to
        indicate the various capabilities of hosts today which do have the marking capability
   and they even do not depend on end host. Only those bits
        are set that represent a DCLASS object from specific capability of the network. end host. The
        bits that are unused MUST be left reset

   draft-ietf-issll-rsvp-cap-02.txt	                     February, 2001

        An example;
          CAP field:

	  0x0X: A_Cap
		The
   marking host/node capability/willingness identifier.
		If A_Cap bit is based on a default mapping from requested service type to reset, the DSCP. In this section, we will briefly address sender host/upstream node
                does not have the deployment
   scenarios for such hosts which do mark without signaling network
   about their marking capability. capability
		If a host A_Cap bit is set, the sender host/upstream node does not provide a CAP object, then
                have the network edge must
   be provisioned (or be given policies) as to how it should react. This
   may be one of:
    - send a DCLASS object.
    - install capability

          Note: A_Cap represents a filter to mark the appropriate flow at single capability/willingness of the edge.
    - do both. end
                host/upstream network node

     2. The problem here CAP Object is ensuring that the mapping configured inserted in the host
   matches the allowed mappings configured RSVP message in the edge router. If there appropriate
        place.

5.2 Message Reception (Downstream Router)

   RSVP PATH message is a mismatch, the edge router will, processed at best, remark the packets to
   match its policies (possibly resulting in a treatment different from
   that expected by the host) or, at worst, mark packets downstream router as non-conforming
   and discard them. specified in
   [RSVP] with following modifications.

     1. The policy may be for a specific host address, for
   a specific interface, for a specific edge router or for records the entire
   domain. The bottom line is that manual provisioning would be required
   in CAP object as the interim until hosts support micro-flow PATH state

     2. The router modifies the CAP option. Once hosts support object by setting the CAP option, manual provisioning would no longer be required.

   In a multi-domain scenario, the boundary router 'B' could be the first
   and field to
        reflect its own capabilities

5.3 Message Reception (Upstream Router)

   RSVP RESV message is processed at the only upstream router as specified in the first DS domain who is dealing
   [RSVP] with following modifications.

     1. The router checks the
   CAP/DCLASS objects (maintaining the recorded PATH state information and deciding for
   a DSCP for the upstream end host). This will allow only one router
   in a domain with micro-flow and
        installs any rules required to handle the knowledge traffic

     2. If the router is not aware of the host's capability and will be rules, it SHOULD seek the one responsible for deciding/providing a DCLASS policy
        rules from the domain policy server

6. IANA Considerations

   The format of CAP object in requires a class number (C-Num) in RSVP
   RESV
   message. In this scenario, the boundary router 'B' becomes Moreover, the DS
   edge for capabilities defined through the end host.

  6. CAP object
   will be defined in other RFCs and their values will be assigned
   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
   [DS] An Architecture for Differentiated Services.  S. Blake, D. Black,
   M. Carlson, E. Davies, Z. Wang, W. Weiss,
   Operation over Diffserv Networks", RFC 2475, December 1998.

   draft-ietf-issll-rsvp-cap-01.txt	                   November, 2998, November 2000

   draft-ietf-issll-rsvp-cap-02.txt	                     February, 2001

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

   [DCLASS] Bernet, Y., "Format of the RSVP DCLASS Object",
   IETF <draft-ietf-isll-dclass-01.txt>, Oct., 1999.

7.

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

8. Acknowledgments

   Thanks to Bill Gage, Yoram Bernet, Goran Janevski, Gary Kenward,
   kwok Ho chan, Muhammad Jaseemuddin Bernet and Louis-Nicolas Hamer other ISSLL WG members for providing useful
   comments to make this one happen. Special thanks to Bill Gage for
   reviewing this draft and providing useful input.

8.

9. Author's Address

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

9.

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   draft-ietf-issll-rsvp-cap-01.txt	                   November, 2000

   draft-ietf-issll-rsvp-cap-02.txt	                   February, 2001