Internet DRAFT - draft-takacs-ccamp-revertive-ps
draft-takacs-ccamp-revertive-ps
Network Working Group A. Takacs
Internet-Draft F. Fondelli
Intended status: Standards Track B. Tremblay
Expires: January 5, 2016 Ericsson
Z. Ali
Cisco Systems
July 6, 2015
RSVP-TE Recovery Extension for data plane initiated reversion,
and protection timer signaling
draft-takacs-ccamp-revertive-ps-11
Abstract
RSVP-TE recovery extensions are specified in [RFC4872] and
[RFC4873]. Currently recovery signaling does not support the
request for revertive protection and recovery timers values. This
document extends the PROTECTION Object format allowing sub-TLVs, and
defines two sub-TLVs to carry wait-to-restore and hold-off
intervals.
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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
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on January 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Updated PROTECTION Object format and sub-TLVs . . . . . . . . 6
3. Error handling . . . . . . . . . . . . . . . . . . . . . . . . 9
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
Generalized MPLS (GMPLS) extends MPLS to include support for
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 regardless of the switching technology (e.g. TDM,
LSC, etc). GMPLS RSVP-TE signaling has been extended to support the
various protection schemes and establish Label Switched
Paths (LSPs) configuring its specific protection characteristics
[RFC4426][RFC4872].
Currently RSVP-TE extensions do not address the values of
protection switching timers. It also does not provide information on
the protection switching operation mode (i.e., revertive or non-
revertive) and sub-network connection (SNC) protection options.
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
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.
WTR, HOFF timers and SNC protection options must be accurately
configured at both ends of the LSP. Operators may need to tune WTR
and HOFF timers on a per LSP basis to ensure best protection
switching performance (e.g., account for differential delays between
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worker and protection paths). Currently 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
signaling carries the necessary information.
This document extends the PROTECTION Object format allowing sub-TLVs,
and defines three sub-TLVs to carry WTR, HOFF timer values and SNC
protection options.
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2. Updated PROTECTION Object format and sub-TLVs
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. The new format updates the PROTECTION Object format of
C-Type TBD (suggested value 3). The updated format is depicted below.
IANA is requested to maintain the TLV space for the PROTECTION Object.
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(TBD) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|P|N|O| Reserved | LSP Flags | Reserved | Link Flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I|R| Reserved | Seg.Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub-TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This document specifies three new 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
SNC protection options sub-TLV specifies attributes of the SNC
protection.
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 (3) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|mode | TCM-ID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mode field (3 bits): The mode values are defined as follows:
SNC Protection Mode Value
------------------- -----
Reserved 0x0
SNC/N 0x1
(Sub Network Connection protection
with Non-intrusive monitoring)
SNC/I 0x2
(Sub Network Connection protection
with Inherent monitoring)
SNC/S 0x3
(Sub Network Connection protection
with Sub-layer monitoring)
TCM-ID: Tandem Connection Monitoring Identifier used. This is applicable
when SNC mode is set to SNC/S.
Reserved field (29 bits): This field is reserved for future use. It
MUST be set to 0 when sent and MUST be ignored when received.
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
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options sub-TLVs 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 signaling, 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).
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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" or
"Routing Problem/Unsupported HOFF value".
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4. IANA Considerations
4.1. New TLV space for the PROTECTION object
A new TLV space needs to be opened and maintained for the PROTECTION
Object in the "Class Names, Class Numbers, and Class Types "
Registry.
4.3. New RSVP error sub-code
For Error Code = 24 "Routing Problem" (see [RFC3209]) the following
sub-codes are defined.
Sub-code Value
-------- -----
Unsupported WTR value To be assigned by IANA
Unsupported HOFF value To be assigned by IANA
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5. Security Considerations
This document introduces no new security issues. The considerations
in [RFC4872] and [RFC4873] apply.
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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.
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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
Zafar Ali
Cisco Systems
Email: zali@cisco.com
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