draft-ietf-issll-rsvp-cap-03.txt
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
This document is an Internet-Draft and is in full conformance with
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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",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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
5.1.3.1 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
modifications.
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.
5.1.3.2 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
zero.
2. The router MUST set the D_MARK bit in the CAP object to reflect
its own marking capability for the downstream nodes.
5.1.3.3 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
10. Full Copyright Statement
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