MPLS Working Group Z. Ali
G. Swallow
Internet Draft Cisco Systems, Inc.
R. Aggarwal
Juniper Networks
Intended status: Standard Track February 2007
Expires: August 2007
Non PHP Behavior and out-of-band mapping for RSVP-TE LSPs
draft-ali-mpls-rsvp-te-no-php-oob-mapping-00.txt
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Abstract
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There are many deployment scenarios which require Egress LSR to
receive binding of the RSVP-TE TE LSP to an application, and
payload identification, using some "out-of-band" (OOB) mechanism.
This document proposes protocol mechanisms to address this
requirement. The procedures described in this document are
equally applicable for point-to-point (P2P) and point-to-
multipoint (P2MP) LSPs.
Conventions used in this document
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
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 0.
Table of Contents
1. Introduction...............................................2
2. RSVP-TE signaling extensions...............................3
2.1. Signaling non-PHP behavior............................3
2.2. Signaling OOB Mapping Indication......................4
2.3. Relationship between OOB and non-PHP bits.............4
2.4. Egress Procedure for label binding....................5
3. Security Considerations....................................5
4. IANA Considerations........................................5
4.1. Attribute Flags for LSP_ATTRIBUTES object.............5
5. Acknowledgments............................................6
6. References.................................................6
6.1. Normative References..................................6
6.2. Informative References................................6
Author's Addresses............................................7
Intellectual Property Statement...............................7
Disclaimer of Validity........................................7
1. Introduction
When RSVP-TE is used for applications like MVPN [MVPN] and VPLS
[VPLS], an Egress LSR receives the binding of the RSVP-TE TE LSP
to an application, and payload identification, using an "out-of-
band" (OOB) mechanism (e.g., using BGP). In such cases, the
Egress LSR cannot make correct forwarding decision until such OOB
mapping information is received. Furthermore, in order to apply
the binding information, the Egress needs to identify the
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incoming LSP. Therefore, non Penultimate Hop Popping (non-PHP)
behavior is required at the Egress for OOB mapping.
There are other applications that require non-PHP behavior. When
RSVP-TE P2MP LSPs are used to carry IP multicast traffic non-PHP
behavior enables a leaf LSR to identify the P2MP TE LSP, on which
traffic is received. Hence the egress LSR can determine whether
traffic is received on the expected P2MP LSP and discard traffic
that is not received on the expected P2MP LSP. Non-PHP behavior
is also required to determine the context of upstream assigned
labels [UPSTREAM] when the context is a MPLS LSP.
This document defines two new bits in the Attributes Flags TLV of
the LSP_ATTRIBUTES object defined in [RFC4420]: one bit for
communication of non-PHP behavior, and one bit to indicate that
the binding of the LSP to an application and payload identifier
(Id) needs to be learned via an out-of-band mapping mechanism.
The procedures described in this document are equally applicable
for P2P and P2MP LSPs. Specification of the OOB communication
mechanism(s) is beyond the scope of this document.
2. RSVP-TE signaling extensions
This section describes the signaling extensions required to
address the above-mentioned requirements.
2.1. Signaling non-PHP behavior
In order to request non-PHP behavior for RSVP-TE LSP, this
document defines a new bit in the Attributes Flags TLV of the
LSP_ATTRIBUTES object defined in [RFC4420]:
Bit Number 6 (TBD): non-PHP behavior desired bit.
This bit SHOULD be set by Ingress node in the Attributes Flags
TLV of the LSP_ATTRIBUTES object in the Path message for the LSP
that desires Non-PHP behavior. This bit MUST NOT be modified by
any other nodes in the network. Nodes other than the Egress nodes
SHOULD ignore this bit.
If an egress node receiving the Path message, supports the
LSP_ATTRIBUTES object and the Attributes Flags TLV, and also
recognizes the "non-PHP behavior desired bit", it MUST allocate a
non-NULL local label. If the egress node supports the
LSP_ATTRIBUTES object but does not recognize the Attributes Flags
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TLV, or supports the TLV as well but does not recognize this
particular bit, then it SHOULD simply ignore the above request.
An ingress node requesting non-PHP behavior MAY examine the label
value corresponding to the Egress node(s) in the RRO, and MAY
send a Path Tear to the Egress which assigns a Null label value.
2.2. Signaling OOB Mapping Indication
In order to indicate to the Egress LSR that binding of RSVP-TE
LSP to an application and payload identification is being
communicated by an OOB mechanism, this document defines a new bit
in the Attributes Flags TLV of the LSP_ATTRIBUTES object defined
in [RFC4420]:
Bit Number 7 (TBD): OOB mapping indication bit.
This bit SHOULD be set by Ingress node in the Attributes Flags
TLV of the LSP_ATTRIBUTES object in the Path message for the LSP
that desires OOB mapping. This bit MUST NOT be modified by any
other nodes in the network. Nodes other than the Egress nodes
SHOULD ignore this bit.
If an egress node receiving the Path message, supports the
LSP_ATTRIBUTES object and the Attributes Flags TLV, and also
recognizes the "OOB mapping indication bit", it MUST wait for the
OOB mapping before accepting traffic on the P2MP LSP. This
implies that the egress node MUST NOT setup forwarding state for
the P2MP LSP before it receives the OOB mapping, though it SHOULD
proceed with RSVP-TE signaling and send RESV messages as per
regular RSVP-TE procedures. It MUST also ignore L3PID in the
Label Request Object [RFC3209]. If the egress node supports the
LSP_ATTRIBUTES object but does not recognize the Attributes Flags
TLV, or supports the TLV as well but does not recognize this
particular bit, then it SHOULD simply ignore the above request.
2.3. Relationship between OOB and non-PHP bits
Non-PHP behavior desired and OOB mapping indication bit can
appear and be processed independently of each other. However, as
mentioned earlier, in the context of application discussed in
this draft, OOB mapping require non-PHP behavior. An Ingress node
requesting OOB mapping MAY also set non-PHP behavior desired bit
in the LSP_ATTRIBUTES object in the Path message.
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2.4. Egress Procedure for label binding
RSVP-TE signaling completion and the OOB mapping information
reception happen asynchronously at the Egress. As mentioned in
Section 2, Egress waits for the OOB mapping before accepting
traffic on the P2MP LSP.
In order to avoid unnecessary use of the resources and possible
block-holing of traffic, if the OOB mapping information is not
received within a reasonable time, Egress MAY trigger a Path
Error message with the error code/sub-code "Notify Error/ no OOB
mapping received" for all affected LSPs. If available, and where
notify requests were included when the LSPs were initially setup,
Notify message (as defined in [RFC3473]) MAY also be used for
delivery of this information to the Ingress node. Egress node may
implement a cleanup timer for this purpose. The time-out value is
a local decision at the Egress, with recommended default value is
(to be decided).
3. Security Considerations
This document does not introduce any new security issues above
those identified in [RFC3209], [RFC4420] and [RSVP-TE-P2MP].
4. IANA Considerations
4.1. Attribute Flags for LSP_ATTRIBUTES object
The following new bit is being defined for the Attributes Flags
TLV in the LSP_ATTRIBUTES object. The numeric value is to be
assigned by IANA.
o Non-PHP behavior desired bit - Bit Number 6 (Suggested value).
o OOB mapping indication bit - Bit Number 7 (Suggested value).
These bits are only to be used in the Attributes Flags TLV on a
Path message.
The following new error sub-code for Error Code = 25 "Notify
Error" (see [RFC3209]) is needed. The numeric value for this sub-
code is to be assigned by IANA.
o No OOB mapping received.
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5. Acknowledgments
The authors would like to thank Yakov Rekhter for his suggestions
on the draft.
6. References
6.1. Normative References
[RFC4420] A. Farrel, D. Papadimitriou, J. P. Vasseur and A.
Ayyangar, "Encoding of Attributes for Multiprotocol
Label Switching (MPLS) Label Switched Path (LSP)
Establishment Using RSVP-TE", RFC 4420, February 2006.
[RFC3209] D. Awduche, L. Berger, D. Gan, T. Li, V. Srinivasan,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RSVP-TE-P2MP] R. Aggarwal, D. Papadimitriou, S. Yasukawa, et al,
"Extensions to RSVP-TE for Point-to-Multipoint TE
LSPs", draft-ietf-mpls-rsvp-te-p2mp-07.txt.
[RFC3473] L. Berger, Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
3473, January 2003.
6.2. Informative References
[MVPN] E. Rosen, R. Aggarwal et al, "Multicast in MPLS/BGP IP
VPNs", draft-ietf-l3vpn-2547bis-mcast-03.txt.
[VPLS] R. Aggarwal, et al, "Propagation of VPLS IP Multicast
Group Membership Information", draft-raggarwa-l2vpn-
vpls-mcast-ctrl-00.txt, work in progress.
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[UPSTREAM] R. Aggarwal, J. L. Le Roux "MPLS Upstream Label
Assignment for RSVP-TE", draft-ietf-mpls-rsvp-
upstream-01.txt, work in progress.
Author's Addresses
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
George Swallow
Cisco Systems, Inc.
Email: swallow@cisco.com
Rahul Aggarwal
Juniper Networks
rahul@juniper.net
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