[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]
Versions: 00 01 02 03 04 05 06 07 08
draft-ietf-mpls-tp-mfp-use-case-and-requirements
Network Working Group Z. Cui
Internet-Draft R. Winter
Intended status: Standards Track NEC
Expires: April 30, 2015 H. Shah
Ciena
S. Aldrin
Huawei Technologies
M. Daikoku
KDDI
October 27, 2014
Use Cases and Requirements for MPLS-TP multi-failure protection
draft-cui-mpls-tp-mfp-use-case-and-requirements-03
Abstract
The basic survivability technique has been defined in Multiprotocol
Label Switching Transport Profile (MPLS-TP) network [RFC6378]. That
protocol however is limited to 1+1 and 1:1 protection, not designed
to handle multi-failure protection.
This document introduces some use cases and requirements for multi-
failure protection functionality.
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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."
This Internet-Draft will expire on April 30, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
Cui, et al. Expires April 30, 2015 [Page 1]
Internet-DrafUse Cases and Requirements for MPLS-TP multi-f October 2014
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. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Document scope . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements notation . . . . . . . . . . . . . . . . . . 3
2. m:n protection architecture . . . . . . . . . . . . . . . . . 3
3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. m:1 (m > 1) protection . . . . . . . . . . . . . . . . . 4
3.1.1. pre-configuration . . . . . . . . . . . . . . . . . . 4
3.1.2. on-demand configuration . . . . . . . . . . . . . . . 5
3.1.3. on-demand activation . . . . . . . . . . . . . . . . 5
3.2. m:n (m, n > 1) protection . . . . . . . . . . . . . . . . 5
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Today's packet optical transport networks are able to concentrate
large volumes of traffic onto a relatively small number of nodes and
links. As a result, the failure of a single network element can
potentially interrupt a large amount of traffic. For this reason,
ensuring survivability through network design is an important network
design objective.
The basic survivability technique has been defined in MPLS-TP network
[RFC6378]. That protocol however is limited to 1+1 and 1:1
protection, not designed to handle multi-failure protection.
The multi-failure protection is required for disaster recovery, e.g.,
even during natural disasters and other catastrophic events such as
earthquake or tsunami, the network availability must be provided
especially for high-priority services such as emergency telephone
calls. Existing 1+1 or 1:n protection however is limited to cover
single failure and no sufficient to maintain disaster recovery.
Cui, et al. Expires April 30, 2015 [Page 2]
Internet-DrafUse Cases and Requirements for MPLS-TP multi-f October 2014
The multi-failure protection is also required for hazardous contion,
e.g., when a working path or protection path was closed by network
operator for construction work, the network service will become a
hazardous condition. During this condition time, if another failure
(e.g. a human-error or network entities failure) is occurred on the
protection path, than the operator can't meet service level
agreements (SLA). Thus, the multi-failure condition could put
pressure on network operations.
On the other hand, many network operators have a very limited budget
for improving network survivability. This requires a design
approach, which takes budget limitations into consideration.
To increase the service availability and to reduce the backup network
costs, we propose extend the 1+1 and 1:1 protection protocol to
support the m:1 and m:n architecture type.
1.1. Document scope
This document describes the use cases and requirements for multi-
failure protection in MPLS-TP networks without the use of control
plane protocols. Existing solutions based on control plane such as
GMPLS may be able to restore user traffic when multiple failures
occur. Some networks however do not use full control plane operation
for reasons such as service provider preferences, certain limitations
or the requirement for fast service restoration (faster than
achievable with control plane mechanisms). These networks are the
focus of this document which defines a set of requirements for multi-
failure protection not based on control plane support.
1.2. Requirements notation
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].
2. m:n protection architecture
The following Figure 1 shows a protection domain with n working paths
and m protection paths between ingress node LER-A and egress node
LER-Z.
At the ingress node LER-A, the normal traffic is either permanently
connected to its working path and may be connected to one of the
protection paths (case of broadcast bridge), or is connected to
either its working path or one of the protection paths (case of
selector bridge). At the egress node LER-Z, the normal traffic is
selected from either its working or one of the protection paths.
Cui, et al. Expires April 30, 2015 [Page 3]
Internet-DrafUse Cases and Requirements for MPLS-TP multi-f October 2014
+-----+ +-----+
|LER-A| Working Path #1 |LER-Z|
| |=============================| |
| | .... | |
| | Working Path #n | |
| |=============================| |
| | | |
| | | |
| | Protection Path #1 | |
| |*****************************| |
| | .... | |
| | Protection Path #m | |
| |*****************************| |
+-----+ +-----+
|--------Protection Domain--------|
Figure 1: m:n protection domain
3. Use cases
3.1. m:1 (m > 1) protection
In the MPLS-TP linear protection such as 1+1/1:1 MPLS-TP protection,
when a single failure is detected on the working path, the normal
traffic can be restored to a protection path. The normal traffic
however into a unprotected condition until the working path is
completely repaired, that could put pressure on network operations.
The m:1 protection can increase service availability and reduce
operator's pressure, because it take multiple protection paths to
ensuring high-priority services continue to operate on the 2nd, 3rd
or N th alternate backup, at least one of m protection paths is an
available.
The 2nd, 3rd or N th alternate backup paths may be provided in
following cases.
3.1.1. pre-configuration
Before failure detection and/or notification, the protection
relationship between the working and two or more protection paths
SHOULD be configured and the protection path MUST be identified prior
to use of the protection paths.
The unprotected extra traffic can be transported over the M
protection path whenever the protection paths are not used to carry a
normal traffic.
Cui, et al. Expires April 30, 2015 [Page 4]
Internet-DrafUse Cases and Requirements for MPLS-TP multi-f October 2014
3.1.2. on-demand configuration
The protection relationship between a working path and a protection
path are configured in the normal condition.
Other protection path such as 2nd, 3rd or N th alternate backup path
is configured by either a control protocol or static configuration by
the management system, only after failure detection and/or
notification of either the working path or the protection path.
However, even when the configuration is performed by a control
protocol, e.g. Generalized MPLS (GMPLS), the control protocol SHALL
NOT be used as the primary mechanism for detecting or reporting
network failures, or for initiating or coordinating protection
switch-over. That is, it SHALL NOT be used as the primary resilience
mechanism.
3.1.3. on-demand activation
Before failure detection and/or notification, two or more protection
paths are instantiated between the same ingress-egress node pair as
the working path, but note that the resources of m ( m > 1 )
protection path may not be allocated.
The resource allocation on the m th protection path occurs only after
failure detection and/or notification of either the working path or
the protection path.
Therefore, this mechanism can against multiple failures but requires
activation of the resource of m th protection path at ingress node
and egress node after failure occurrence. After activated the m th
protection path, the ingress node and egress node can carry the
normal traffic.
3.2. m:n (m, n > 1) protection
In order to reduce backup costs, in the m:n architecture type, m
dedicated protection transport paths are sharing backup resources for
n working transport paths.
The bandwidth of each protection path should be allocated in such a
way that it may be possible to protect any of the n working paths in
case at least one of the m protection paths is available. When a
working path is determined to be impaired, its normal user traffic
signal first must be assigned to an available protection transport
path followed by transition from the working to the assigned
protection path at both the ingress node and egress node of the
Cui, et al. Expires April 30, 2015 [Page 5]
Internet-DrafUse Cases and Requirements for MPLS-TP multi-f October 2014
protected domain. It is noted that when more than m working paths
are impaired, only m working paths can be protected
On the other hand, the normal traffic is either permanently connected
to its working path and may be connected to one of the protection
paths. It is noted that when at least one of the m protection paths
is available, than the working path can be protected.
4. Requirements
Some recovery requirements are defined [RFC5654]. That however is
limited to cover single failure and is not able to care that the
multiple failures. This Section 4 extends the requirements to
support the multiple failures scenarios.
MPLS-TP MUST support m:1 protection with the following requirements:
R1 The m:1 protection MUST protects against multiple failures that
are detected on both of working path and protection path.
R2 The backup paths pre-configuration SHOULD be supported.
R3 On-demand backup paths configuration MAY be supported.
R4 On-demand backup resource activation MAY be supported.
R5 Some priority schemes MUST be provided, because a protection path
has to choose between two or more backup resources.
MPLS-TP MUST support m:n protection with the following requirements:
R6 The m:n protection MUST protects against multiple failures that
are simultaneously-detected on both of working path and
protection path or more than one multiple working paths.
R7 Some priority schemes MUST be provided, because the backup
resources are shared by multiple working paths dynamically.
5. Security Considerations
TBD
6. IANA Considerations
TBD
Cui, et al. Expires April 30, 2015 [Page 6]
Internet-DrafUse Cases and Requirements for MPLS-TP multi-f October 2014
7. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5654] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N.,
and S. Ueno, "Requirements of an MPLS Transport Profile",
RFC 5654, September 2009.
[RFC6378] Weingarten, Y., Bryant, S., Osborne, E., Sprecher, N., and
A. Fulignoli, "MPLS Transport Profile (MPLS-TP) Linear
Protection", RFC 6378, October 2011.
Authors' Addresses
Zhenlong Cui
NEC
Email: c-sai@bx.jp.nec.com
Rolf Winter
NEC
Email: Rolf.Winter@neclab.eu
Himanshu Shah
Ciena
Email: hshah@ciena.com
Sam Aldrin
Huawei Technologies
Email: aldrin.ietf@gmail.com
Masahiro Daikoku
KDDI
Email: ms-daikoku@kddi.com
Cui, et al. Expires April 30, 2015 [Page 7]
Html markup produced by rfcmarkup 1.129b, available from
https://tools.ietf.org/tools/rfcmarkup/