CCAMP Working Group Rakesh Gandhi
Internet-Draft Zafar Ali
Intended status: BCP Gabriele Maria Galimberti
Expires: January 16, 2014 Cisco Systems, Inc.
July 15, 2013
RSVP-TE Extensions For Signaling GMPLS Restoration LSP
draft-gandhi-ccamp-gmpls-restoration-lsp-01
Abstract
In transport networks, there are requirements where Generalized
Multi-Protocol Label Switching (GMPLS) recovery scheme need to employ
restoration LSP while keeping resources for the working and/ or
protecting LSPs reserved in the network. Existing GMPLS recovery
procedures do not address these requirements. This document describes
best common practice for using RSVP-TE for GMPLS recovery with
restoration LSP.
Status of this Memo
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This Internet-Draft will expire on May 31, 2013.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 4
3. Restoration LSP Signaling Extensions . . . . . . . . . . . . . 5
3.1. Signaling Procedure . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative references . . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
Generalized Multi-Protocol Label Switching (GMPLS) extends MPLS to
include support for different switching technologies [RFC3471]
[RFC3473]. These switching technologies provide several protection
schemes [RFC4426][RFC4427] (e.g. 1+1, 1:N and M:N). GMPLS RSVP-TE
signaling has been extended to support various recovery schemes to
establish Label Switched Paths (LSPs) [RFC4872][RFC4873], typically
working LSP and protecting LSP. [RFC4427] Section 7 specifies various
schemes for GMPLS restoration.
In GMPLS recovery schemes currently considered, restoration LSP is
signaled after the failure has been detected and notified on the
working LSP. These schemes assume that working LSP is removed from
the network before restoration LSP is signaled. In transport
networks, as working LSPs are typically signaled over a nominal path,
there are many scenarios where service providers would like to keep
resources associated with the working LSPs reserved. This is to make
sure that the service (working LSP) can use the nominal path when the
failure is repaired. Consequently, in transport networks one can
employ a recovery scheme where a new restoration LSP is signaled
while working LSP and/ or protecting LSP are not torn down in control
plane due to a failure. Restoration LSP differs from a secondary LSP
in the way that secondary LSP does not reserve resources in the data
plane and is not able to carry any traffic until it is refreshed
whereas restoration LSP does reserve resources and is able to carry
traffic.
One example of the recovery scheme considered in this draft is 1+R
recovery. The 1+R recovery is exemplified in Figure 1. In this
example, working LSP on path A-B-C-Z is pre-established. Typically
after a failure detection and notification on the working LSP, a
second LSP on path A-H-I-J-Z is established as a restoration LSP.
Unlike protection LSP, restoration LSP is signaled on as needed
basis.
A --- B --- C --- Z
\ /
H --- I --- J
Figure 1: An example of 1+R recovery scheme
During failure with 1+R recovery scheme, in general, working LSP
resources are not released and working and restoration LSPs coexist
in the network. Nonetheless, working and restoration LSPs can share
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network resources. Typically when failure is recovered on the working
LSP, restoration LSP is no longer required and torn down (e.g.
revertive mode).
Another example of the recovery scheme considered in this draft is
1+1+R. In 1+1+R, a restoration LSP is signaled for the working LSP
and/ or the protecting LSP after the failure has been detected and
notified on the working LSP or the protecting LSP. The 1+1+R recovery
is exemplified in Figure 2. In this example, working LSP on path A-B-
C-Z and protecting LSP on path A-D-E-F-Z are pre-established. After a
failure detection and notification on a working LSP or protecting
LSP, a third LSP on path A-H-I-J-Z is established as a restoration
LSP. The restoration LSP in this case provides protection against a
second order failure. Restoration LSP is torn down when the failure
on the working or protecting LSP is repaired.
D --- E --- F
/ \
A --- B --- C --- Z
\ /
H --- I --- J
Figure 2: An example of 1+1+R recovery scheme
[RFC4872] Section 14 defines PROTECTION object for GMPLS recovery
signaling. The PROTECTION object is used to identify primary and
secondary LSPs using S bit and protecting and working LSPs using P
bit. However, the PROTECTION object does not have a way to identify
restoration LSP. [RFC4872] and [RFC6689] define the usage of
ASSOCIATION object for further associating GMPLS working and
protecting LSPs for the case where restoration LSP is signaled for
GMPLS recovery after the working or protecting LSPs are removed.
This draft outlines the best common practice for identifying the
restoration LSP for GMPLS recovery where working and protecting LSP
resources are kept reserved.
2. 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 [RFC2119].
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3. Restoration LSP Signaling Extensions
3.1. Signaling Procedure
Where GMPLS recovery scheme need to employ restoration LSP while
keeping resources for the working and/ or protecting LSPs reserved in
the network, restoration LSP is signaled with ASSOCIATION object with
the association ID set to the LSP ID of the LSP it is restoring. For
example, when a restoration LSP is signaled for a working LSP, the
ASSOCIATION object in the restoration LSP contains the association ID
set to the LSP ID of the working LSP. Similarly, when a restoration
LSP is signaled for a protecting LSP, the ASSOCIATION object in the
restoration LSP contains the association ID set to the LSP ID of the
protecting LSP.
The procedure for signaling the PROTECTION object is specified in
[RFC4872][RFC4873] and does not change. Restoration LSP for the
working LSP is signaled with P bit cleared and restoration LSP for the
protecting LSP is signaled with P bit set.
When using a GMPLS recovery mode, where working LSP is destroyed, and
the restoration LSP is promoted to be the new working LSP, restoration
LSP RSVP Path message MUST be refreshed by using the
ASSOCIATION_OBJECT.LSP_ID from the destroyed working LSP
ASSOCIATION_OBJECT.LSP_ID.
When using a GMPLS recovery mode, where a protecting LSP is destroyed,
and the restoration LSP is promoted to be the new protecting LSP,
restoration LSP RSVP Path message MUST be refreshed by using the
ASSOCIATIN_OBJECT.LSP_ID from the destroyed protecting LSP
ASSOCIATION_OBJECT.LSP_ID.
4. IANA Considerations
This document makes no request for IANA action.
5. Security Considerations
This document introduces no additional security considerations. For a
general discussion on MPLS and GMPLS related security issues, see the
MPLS/GMPLS security framework [RFC5920]. In addition, the
considerations specified in [RFC4872] and [RFC4873] will apply.
6. Acknowledgement
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The authors would like to thank George Swallow for the discussion on
the GMPLS restoration.
7. References
7.1. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Functional Description", RFC
3471, January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC4872] Lang, J., Rekhter, Y., and D. Papadimitriou, "RSVP-TE
Extensions in Support of End-to-End Generalized Multi-
Protocol Label Switching (GMPLS) Recovery", RFC 4872, May
2007.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, May 2007.
[RFC6689] Berger, L, "Usage of the RSVP ASSOCIATION Object", RFC
6689, July 2012.
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7.2. Informative References
[RFC4426] Lang, J., Rajagopalan B., and D.Papadimitriou, Editors,
"Generalized Multiprotocol Label Switching (GMPLS)
Recovery Functional Specification", RFC 4426, March 2006.
[RFC4427] Mannie, E., Ed. and D. Papadimitriou, Ed., "Recovery
(Protection and Restoration) Terminology for Generalized
Multi-Protocol Label Switching, RFC 4427, March 2006.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
Authors' Addresses
Rakesh Gandhi
Cisco Systems, Inc.
Email: rgandhi@cisco.com
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
Gabriele Maria Galimberti
Cisco Systems, Inc.
Email: ggalimbe@cisco.com
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