draft-ietf-issll-rsvp-cap-01.txt   draft-ietf-issll-rsvp-cap-02.txt 
draft-ietf-issll-rsvp-cap-01.txt draft-ietf-issll-rsvp-cap-02.txt
Internet Draft Syed, Hamid, Internet Draft Syed, Hamid
draft-ietf-issll-rsvp-cap-01.txt Nortel Networks draft-ietf-issll-rsvp-cap-02.txt Nortel Networks
November, 2000 February, 2001
Capability Negotiation: The RSVP CAP Object Capability Negotiation: The RSVP CAP Object
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with all This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026. provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Task Internet-Drafts are working documents of the Internet Engineering Task
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Distribution of this memo is unlimited. Distribution of this memo is unlimited.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved. Copyright (C) The Internet Society (2001). All Rights Reserved.
1. Abstract 1. Abstract
The DCLASS object is proposed in [DCLASS] to represent and carry The resource reservation protocol [RSVP] is an end-to-end signaling
Differentiated Services Code Points (DSCPs) within RSVP messages. The protocol and it can be a useful mechanism to carry the upstream node or
principle use of the DCLASS object is to carry DSCP information network capabilities/willingness to the downstream network/nodes.
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.
There may be situations where the sender host is not capable or may
not wish to mark the packets. Currently, there is no way for the
host or network devices to specify their capabilities to the downstream
nodes.
This draft proposes a capability object (CAP object) in the RSVP PATH
message that can be used to convey end host/upstream node
capabilities 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 a DCLASS object from the This draft proposes a capability negotiation object, CAP object, in the
downstream network and marking the downstream packets. RSVP PATH message that can be used to convey end host/upstream node
capabilities to the downstream network/nodes.
2. Introduction 2. Introduction
The mechanics of using RSVP [RSVP] signalling and the DCLASS object In today's heterogenous networking environment, it is important for each
for requesting and applying the QoS in a differentiated services [DS] network to have a knowledge of its upstream nodes/network capabilities
network is described fully in [INTDIFF]. It assumes an architecture before it can perform any actions to support the QoS requirements of the
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 draft-ietf-issll-rsvp-cap-02.txt February, 2001
The capability object called 'CAP' object can be used as a mechanism flows from upstream networks. Such an advance information would help the
for conveying node capabilities or willingness in RSVP messages. As an network operator to configure the network according to the expected
example, we will focus on the marking capability of nodes throughout nature of traffic that the network devices have to process and route.
this document and define a single bit for host marking information to The current standards does not provide any way to the end host or
be carried in the CAP field inside the CAP object of RSVP PATH message. 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.
draft-ietf-issll-rsvp-cap-01.txt November, 2000 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.
However, the CAP is a generic object that can be used to carry any other 3. Conventions used in this document
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 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
- Border Router-Border Router interaction "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC-2119].
It should be noted that how and when the packets will be marked is a 4. Format of CAP Object
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 CAP object has the following format:
The advance knowledge of the end host's capabilities may help the 0 | 1 | 2 | 3
network edge devices to make policy decisions on end host's requests. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
These capabilities can be indicated in the RSVP PATH message to the | Length | C-Num (TBD) | C-Type=1 |
downstream edge devices. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CAP field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The end hosts can be classiffied in two categories: Those capable of The CAP field is defined with full 32 bits in the object. Each bit in
marking downstream packets and decide to do so. The other category of the field can be used for one specific capability representation.
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 5. Message Processing Rules
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 5.1 Message Generation (RSVP Host)
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 An RSVP PATH message is created as specified in [RSVP] with following
modifications
3.2 Boundry router-Boundry Router Interaction 1. A capability (CAP) object is created and the CAP field is set to
indicate the various capabilities of the end host. Only those bits
are set that represent a specific capability of the end host. The
bits that are unused MUST be left reset
The CAP object could be carried in the PATH message end-to-end. The RSVP draft-ietf-issll-rsvp-cap-02.txt February, 2001
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 An example;
marked is a decision governed by the network policies. The network CAP field:
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.
+----------+ +-----------+ 0x0X: A_Cap
|DS domain | |DS domain | The host/node capability/willingness identifier.
| 1 | | 2 | If A_Cap bit is reset, the sender host/upstream node
+----+ +----+ +----+ +----+ +----+ +----+ does not have the capability
|Host|-----| A | | B |----| C | | D |---''''''|Host| If A_Cap bit is set, the sender host/upstream node does
+----+ +----+ +----+ +----+ +----+ +----+ have the capability
| | | |
| | | |
+----------+ +-----------+
Figure 1 Note: A_Cap represents a single capability/willingness of the end
host/upstream network node
4. Format of CAP Object 2. The CAP Object is inserted in the RSVP message in the appropriate
place.
The CAP object has the following format: 5.2 Message Reception (Downstream Router)
0 | 1 | 2 | 3 RSVP PATH message is processed at the downstream router as specified in
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ [RSVP] with following modifications.
| Length | C-Num (226) | C-Type=1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CAP field |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
draft-ietf-issll-rsvp-cap-01.txt November, 2000 1. The router records the CAP object as the micro-flow PATH state
CAP field: 2. The router modifies the CAP object by setting the CAP field to
reflect its own capabilities
0x01: D_MARK 5.3 Message Reception (Upstream Router)
The host marking capability/willingness identifier.
If D_MARK bit is reset, the sender host/upstream node
is not able to mark packets
If D_MARK bit is set, the sender host/upstream node is
able/willing to mark packets
Note: D_MARK is a bit in the CAP (capbility) field. RSVP RESV message is processed at the upstream router as specified in
[RSVP] with following modifications.
5. Deployment Scenarios 1. The router checks the recorded PATH state for the micro-flow and
installs any rules required to handle the traffic
There are a number of hosts today which do have the marking capability 2. If the router is not aware of the rules, it SHOULD seek the policy
and they even do not depend on a DCLASS object from the network. The rules from the domain policy server
marking is based on a default mapping from requested service type to
the DSCP. In this section, we will briefly address the deployment
scenarios for such hosts which do mark without signaling network
about their marking capability.
If a host does not provide a CAP object, then the network edge must 6. IANA Considerations
be provisioned (or be given policies) as to how it should react. This
may be one of:
- send a DCLASS object.
- install a filter to mark the appropriate flow at the edge.
- do both.
The problem here is ensuring that the mapping configured in the host
matches the allowed mappings configured in the edge router. If there
is a mismatch, the edge router will, 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 as non-conforming
and discard them. The policy may be for a specific host address, for
a specific interface, for a specific edge router or for the entire
domain. The bottom line is that manual provisioning would be required
in the interim until hosts support the CAP option. Once hosts support
the CAP option, manual provisioning would no longer be required.
In a multi-domain scenario, the boundary router 'B' could be the first The format of CAP object requires a class number (C-Num) in RSVP
and the only router in the first DS domain who is dealing with the message. Moreover, the capabilities defined through the CAP object
CAP/DCLASS objects (maintaining the state information and deciding for will be defined in other RFCs and their values will be assigned
a DSCP for the upstream end host). This will allow only one router through IANA.
in a domain with the knowledge of the host's capability and will be
the one responsible for deciding/providing a DCLASS object in a RSVP
RESV message. In this scenario, the boundary router 'B' becomes the DS
edge for the end host.
6. References 7. References
[INTDIFF], Bernet, Y., Yavatkar, R., Ford, P., Baker, F., Zhang, L., [INTDIFF], Bernet, Y., Yavatkar, R., Ford, P., Baker, F., Zhang, L.,
Speer, M., Braden, R., Davie, B., Wroclawski, J., "Integrated Services Speer, M., Braden, R., Davie, B., Wroclawski, J., "Integrated Services
[DS] An Architecture for Differentiated Services. S. Blake, D. Black, Operation over Diffserv Networks", RFC 2998, November 2000
M. Carlson, E. Davies, Z. Wang, W. Weiss, RFC 2475, December 1998.
draft-ietf-issll-rsvp-cap-01.txt November, 2000 draft-ietf-issll-rsvp-cap-02.txt February, 2001
[RSVP] Braden, R. ed., "Resource ReSerVation Protocol (RSVP) - [RSVP] Braden, R. ed., "Resource ReSerVation Protocol (RSVP) -
Functional Specification.", IETF RFC 2205, Sep. 1997. Functional Specification.", IETF RFC 2205, Sep. 1997.
[DCLASS] Bernet, Y., "Format of the RSVP DCLASS Object", [RFC-2119] S. Bradner, "keywords for use in RFCs to Indicate Requirement
IETF <draft-ietf-isll-dclass-01.txt>, Oct., 1999. Levels", RFC 2119 (BCP), IETF, March 1997.
7. Acknowledgments 8. Acknowledgments
Thanks to Bill Gage, Yoram Bernet, Goran Janevski, Gary Kenward, Thanks to Yoram Bernet and other ISSLL WG members for providing useful
kwok Ho chan, Muhammad Jaseemuddin and Louis-Nicolas Hamer for comments to make this one happen. Special thanks to Bill Gage for
reviewing this draft and providing useful input. reviewing this draft
8. Author's Address 9. Author's Address
Syed, Hamid Syed, Hamid
Nortel Networks Nortel Networks
100 - Constellation Crescent, 100 - Constellation Crescent,
Nepean, ON K2G 6J8 Nepean, ON K2G 6J8
Phone: (613) 763-6553 Phone: (613) 763-6553
Email: hmsyed@nortelnetworks.com Email: hmsyed@nortelnetworks.com
9. Full Copyright Statement 10. Full Copyright Statement
"Copyright (C) The Internet Society (date). All Rights Reserved. "Copyright (C) The Internet Society (date). All Rights Reserved.
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others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. However, this are included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
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The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN
WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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