Network Working Group A. Takacs
Internet-Draft F. Fondelli
Intended status: Standards Track B. Tremblay
Expires: September 10, 2009 Ericsson
March 9, 2009
GMPLS RSVP-TE recovery extension for data plane initiated reversion
draft-takacs-ccamp-revertive-ps-03
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 10, 2009.
Takacs, et al. Expires September 10, 2009 [Page 1]
Internet-Draft GMPLS revertive protection signalling March 2009
Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Takacs, et al. Expires September 10, 2009 [Page 2]
Internet-Draft GMPLS revertive protection signalling March 2009
Abstract
GMPLS RSVP-TE recovery extensions are specified in [RFC4872] and
[RFC4873]. Currently these extensions cannot signal request for
revertive protection neither values for the associated timers to the
remote endpoint. This document extends the PROTECTION Object
allowing sub-TLVs, and defines two sub-TLVs to carry wait-to-restore
and hold-off intervals.
Takacs, et al. Expires September 10, 2009 [Page 3]
Internet-Draft GMPLS revertive protection signalling March 2009
Requirements Language
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
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. PROTECTION object extension . . . . . . . . . . . . . . . . . 7
3. Error handling . . . . . . . . . . . . . . . . . . . . . . . . 9
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
Intellectual Property and Copyright Statements . . . . . . . . . . 14
Takacs, et al. Expires September 10, 2009 [Page 4]
Internet-Draft GMPLS revertive protection signalling March 2009
1. Introduction
Generalised MPLS (GMPLS) extends MPLS to include support of different
switching technologies [RFC3471]. These switching technologies
provide several protection schemes [RFC4426][RFC4427] (e.g. 1+1, 1:N,
M:N). Many characteristics of those protection schemes are common
disregard of the switching technology (e.g. TDM, LSC, etc). GMPLS
RSVP-TE signalling has been extended to support the various
protection schemes and establish connections (Label Switched Paths
(LSPs)) configuring its specific protection characteristics
[RFC4426][RFC4872].
Currently RSVP-TE extensions do not address the configuration of
protection switching timers neither provide information on the
protection switching operation mode (i.e., revertive or non-
revertive).
The Hold-off time (HOFF) is defined as the time between the reporting
of signal fail or degrade, and the initialization of the recovery
switching operation [RFC4427]. This timer is useful to limit the
number of switch actions when multiple layers of recovery are being
used, or in case of 1+1 unidirectional protection scheme [G.808.1] to
prevent too early switching due to the differential delay difference
between the short and long path.
The Wait-to-Restore time (WTR) is defined as a period of time that
must elapse after a recovered fault before an LSP can be used again
to transport the normal traffic and/or to select the normal traffic
from the LSP [RFC4427]. The WTR time is fundamental in revertive
mode of operation, to prevent frequent operation of the protection
switch due to an intermittent defect [G.808.1].
Reversion refers to the process of moving normal traffic back to the
original working LSP after the failure is cleared and the path is
repaired [RFC4426][RFC4427][RFC4872]. In transport networks
reversion is desirable since the protection path may not be optimal
from a routing and resource consumption point of view, additionally,
moving traffic back to the working LSP allows the protection
resources to be used to protect other LSPs. On the other hand,
reversion requires that the working resources remain allocated during
failure. The operator needs to have the choice between revertive and
non-revertive protection to balance the pros and cons in a given
situation.
WTR and HOFF timers must be accurately configured at both ends of the
LSP. Operators may need to tune these timers on a per LSP basis to
ensure best protection switching performance (e.g., account for
differential delays between worker and protection paths). Currently
Takacs, et al. Expires September 10, 2009 [Page 5]
Internet-Draft GMPLS revertive protection signalling March 2009
these values are either pre-configured to a default value (and so may
be suboptimal for some of the LSPs) or need to be manually set/tuned
after the connections have been established. Since these parameters
are important for recovery in transport networks, it is desirable
that GMPLS RSVP-TE protection signalling carries the necessary
information.
This document extends the PROTECTION Object allowing sub-TLVs, and
defines sub-TLVs to carry WTR and HOFF values.
Takacs, et al. Expires September 10, 2009 [Page 6]
Internet-Draft GMPLS revertive protection signalling March 2009
2. PROTECTION object extension
In [RFC4872] and [RFC4873] the PROTECTION object is specified to
support end-to-end and segment recovery. In order to ease addition
of protection attributes the PROTECTION Object is extended to carry
sub-TLVs. This is depicted below. A new C-Type (3 IANA to assign)
is allocated for the new format. This document specifies two new
sub-TLVs.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num(37) | C-Type(3 IANA)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|P|N|O| Reserved | LSP Flags | Reserved | Link Flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
WTR - Wait-to-Restore time sub-TLV specifies the WTR time. If the
WTR field is 0 the protection switching operation mode is non-
revertive, otherwise revertive operation with the signalled timer (in
milliseconds) is requested. The value 0xffffffff is reserved, and
refers to a locally pre-configured WTR value.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (1) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| WTR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
HOFF - Hold-off time sub-TLV specifies the HOFF time. The values are
in milliseconds. The value 0xffffffff is reserved, and refers to a
locally pre-configured HOFF value.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (2) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HOFF |
Takacs, et al. Expires September 10, 2009 [Page 7]
Internet-Draft GMPLS revertive protection signalling March 2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In the case of end-to-end protection the PROTECTION Object is
inserted at the top level in the Path message, the WTR and HOFF
fields correspond to the end-to-end protection. In the case when a
segment of the LSP is to be protected and the WTR and HOFF timers for
the protection segment are to be set by signalling, explicit segment
recovery control has to be used, i.e., the PROTECTION Object with the
desired timers set must be inserted in the appropriate Secondary
Explicit Route Object (SERO).
Takacs, et al. Expires September 10, 2009 [Page 8]
Internet-Draft GMPLS revertive protection signalling March 2009
3. Error handling
In the case a specific configuration of the timers is not supported
the corresponding error should be generated and sent in the PathErr
message: "Routing Problem/Unsupported WTR value" and/or "Routing
Problem/Unsupported HOFF value".
Takacs, et al. Expires September 10, 2009 [Page 9]
Internet-Draft GMPLS revertive protection signalling March 2009
4. IANA Considerations
A new C-Type (3) is to be assigned for the modified PROTECTION Object
in the "Class Names, Class Numbers, and Class Types " Registry.
New error values need to be added to "Error Codes and Globally-
Defined Error Value Sub-Codes " Registry for the "Routing Problem"
Error Code: "Unsupported WTR value" and "Unsupported HOFF value".
Takacs, et al. Expires September 10, 2009 [Page 10]
Internet-Draft GMPLS revertive protection signalling March 2009
5. Security Considerations
This document introduces no new security issues. The considerations
in [RFC4872] and [RFC4873] apply.
Takacs, et al. Expires September 10, 2009 [Page 11]
Internet-Draft GMPLS revertive protection signalling March 2009
6. References
[G.808.1] "Generic protection switching -- Linear trail and
subnetwork protection", ITU-T Recommendation G.808.1,
March 2006.
[IEEE-PBBTE]
"IEEE 802.1Qay Draft Standard for Provider Backbone
Bridging Traffic Engineering", work in progress.
[RFC3471] "Generalized Multi-Protocol Label Switching (GMPLS)
Signaling Functional Description", RFC 3471, January 2003.
[RFC4426] "Generalized Multi-Protocol Label Switching (GMPLS)
Recovery Functional Specification", RFC 4426, March 2006.
[RFC4427] "Recovery (Protection and Restoration) Terminology for
Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4427, March 2006.
[RFC4872] "RSVP-TE Extensions in Support of End-to-End Generalized
Multi-Protocol Label Switching (GMPLS) Recovery",
RFC 4872, May 2007.
[RFC4873] "GMPLS Segment Recovery", RFC 4873, May 2007.
Takacs, et al. Expires September 10, 2009 [Page 12]
Internet-Draft GMPLS revertive protection signalling March 2009
Authors' Addresses
Attila Takacs
Ericsson
Laborc u. 1.
Budapest, 1037
Hungary
Email: attila.takacs@ericsson.com
Francesco Fondelli
Ericsson
Via Negrone
Genova, 16153
Italy
Email: francesco.fondelli.ericsson.com
Benoit Tremblay
Ericsson
8400 Decarie.
Montreal, Quebec H4P 2N2
Canada
Email: benoit.c.tremblay@ericsson.com
Takacs, et al. Expires September 10, 2009 [Page 13]
Internet-Draft GMPLS revertive protection signalling March 2009
Takacs, et al. Expires September 10, 2009 [Page 14]