MPLS Working Group G. Liu
Internet-Draft ZTE Corporation
Intended status: Informational Y. Weingarten
Expires: October 29, 2012 April 27, 2012
MPLS-TP protection for interconnected rings
draft-liu-mpls-tp-interconnected-ring-protection-02
Abstract
According to the ring protection Requirements in RFC 5654,
Requirement 93 : When a network is constructed from interconnected
rings, MPLS-TP MUST support recovery mechanisms that protect user
data that traverses more than one ring. This includes the
possibility of failure of the ring-interconnect nodes and links,so
this document will describle all kinds of interconnected ring
Scenarios and several protection solutions for recovery the failure
of the ring-interconnect nodes and Links. .
This document is a product of a joint Internet Task Force(IETF) /
International Telecommunications Union Telecommunications
Standardization Sector (ITU-T) effort to include an MPLS Transport
Profile within the IETF MPLS and PWE3 architectures to support the
capabilities and functionalities of a packet transport network as
defined by the ITU-T.
Status of this Memo
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provisions of BCP 78 and BCP 79. This document may not be modified,
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This Internet-Draft will expire on October 29, 2012.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 7
3. recovery mechanisms . . . . . . . . . . . . . . . . . . . . . 8
3.1. recovery mechanism for Dual-node interconnected-ring . . . 8
3.2. recovery mechanism for Chained interconnected-ring . . . . 8
3.3. recovery mechanism for Dual-node and Single-node mixed
interconnected-ring . . . . . . . . . . . . . . . . . . . 9
3.4. recovery mechanism for Dual-node and Chained mixed
interconnected-ring . . . . . . . . . . . . . . . . . . . 9
3.5. recovery mechanism for Single-node and Chained mixed
interconnected-ring . . . . . . . . . . . . . . . . . . . 9
3.6. recovery mechanism for Dual-node ,Single-node and
Chained mixed interconnected-ring . . . . . . . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
7.3. URL References . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
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1. Introduction
This document describles different interconnected ring scenarios and
several protection solutions to protect against the failure of the
ring-interconnect nodes and links. there are mainly three common
interconnection scenarios that we will address in this document:
Dual-node interconnection - when the interconnected rings are
interconnected by two nodes from each ring (see Figure 1);
Single-node interconnection - when the connection between the
interconnected rings are through a single node (see Figure 2).As the
interconnnection node(LSR-A) is a single-point of failure, such the
interconnection scenario should be avoided in real network;
Chain of rings - when a series of rings are connected through
interconnection nodes that are part of both interconnected rings (see
Figure 3)
/LSR\******/LSR\******/LSR\xxxx/LSR\*****/LSR\******/LSR\
\_C_/ \_B_/ \_A_/ \_6_/ \_1_/ \_2_/
* * x x * *
* Ring #1 * x x * Ring #2 *
_*_ ___ _*_ x _*_ ___ _*_
/LSR\ /LSR\ /LSR\x x /LSR\ /LSR\ /LSR\
\_D_/******\_E_/******\_F_/xxxx\_5_/*****\_4_/******\_3_/
*** physical link
xxx interconnection link
Figure 1
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___ ___ ___ ___
/LSR\**********/LSR\ /LSR\*********/LSR\
\_C_/ \_B_/* *\_1_/ \_2_/
* * * *
* * * *
* * * *
_*_ * ___ * _*_
/LSR\ Ring #1 /LSR\ Ring #2 /LSR\
\_D_/ *\_A_/* \_3_/
* * * *
* * * *
* * * *
_*_ ___* *___ _*_
/LSR\ /LSR\ /LSR\ /LSR\
\_E_/***********\_F_/ \_5_/**********\_4_/
*** physical link
Figure 2
___ ___ ___ ___ ___
/LSR\******/LSR\******/LSR\*****/LSR\******/LSR\
\_C_/ \_B_/ \_A_/ \_1_/ \_2_/
* x *
* Ring #1 x Ring #2 *
_*_ ___ _x_ ___ _*_
/LSR\ /LSR\ /LSR\ /LSR\ /LSR\
\_D_/******\_E_/******\_F_/*****\_4_/******\_3_/
*** physical link
xxx shared link
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Figure 3
Regarding traffic that traveres more than two rings.the different
interconnection scenarios could be mixed.
Dual-node and single-node mixed interconnection-when there not only
exist two interconnected rings are interconnected by two nodes from
each ring. but also there exist two interconnected rings are
interconnected by single node( see figure 5);
Dual-node and chained mixed interconnection-when there exist two
interconnnected rings are interconnected by two nodes from each ring.
in addtion, there still exist two interconnnected rings are
interconnected by a common chained link(see figure 4);
single-node and chained mixed interconnection-when there exist two
interconnected rings are interconnected by single node, in addtion,
there still exist two interconnected rings are interconnected by a
common chained link(see figure 6);
Dual-node, single-node and chained mixed interconnection-when there
exist all three interconnection scenrios in the network domain
including Dual-node interconnnection, single-node interconnection and
chained interconnnection( see figure 7);
___
/LSR\******/LSR\xx/LSR\****/LSR\ /LSR\**** /LSR\***/LSR\
\_C_/ \_B_/ \_A_/ \_6_/ \_1_/ \_2_/ \_H_/
* * x x * * * x *
x * x *
* Ring 1 * x x * Ring 2 * .....*Ring 3 x Ring 4*
_*_ *x x_*_ _*_ ___ ___ ___
/LSR\ /LSR\ /LSR\ /LSR\ /LSR\*****/LSR\**/LSR\
\_D_/******\_E_/xx\_5_/*****\_4_/ \_k_/ \_L_/ \_M_/
*** physical link
xxx interconnection link
Figure 4
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___
/LSR\******/LSR\xx/LSR\****/LSR\ /LSR\ /LSR\
\_C_/ \_B_/ \_A_/ \_6_/ \_1_/ *\_H_/
* * x x * * * * * *
x * * ___ * *
* Ring 1 * x x * Ring 2 * .....*Ring 3/LSR\ Ring 4*
_*_ *x x_*_ _*_ ___ * \_L_/* ___
/LSR\ /LSR\ /LSR\ /LSR\ /LSR\* * /LSR\
\_D_/******\_E_/xx\_5_/*****\_4_/ \_k_/ \_M_/
*** physical link
xxx interconnection link
Figure 5
___
/LSR\******/LSR\**/LSR\****/LSR\ /LSR\ /LSR\
\_C_/ \_B_/ \_A_/ \_6_/ \_1_/ *\_H_/
* x * * * * *
* * ___ * *
* Ring 1 x Ring 2 * .....*Ring 3/LSR\ Ring 4*
_*_ _ _x_ _*_ ___ * \_L_/* ___
/LSR\ /LSR\ /LSR\ /LSR\ /LSR\* * /LSR\
\_D_/******\_E_/**\_5_/*****\_4_/ \_k_/ *\_M_/
*** physical link
xxx interconnection link
Figure 6
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___
/LSR\******/LSR\xx/LSR\****/LSR\**** /LSR\ /LSR\
\_C_/ \_B_/ \_A_/ \_6_/ \_1_/ *\_H_/
* * x x * x x * * *
x x * ___ * *
* Ring 1 * x x * Ring 2 xRing 5 xRing 3/LSR\ Ring 4*
_*_ *x x_*_ _x_ ___ * \_L_/* ___
/LSR\ /LSR\ /LSR\ /LSR\****/LSR\* * /LSR\
\_D_/******\_E_/xx\_5_/*****\_4_/ \_k_/ *\_M_/
*** physical link
xxx interconnection link
Figure 7
For a multi-ring service, it will be accross more than one ring just
like above seven scenrios. if a failur happens on a multi-ring path,
quickly recovery is necessary requirement for MPLS-TP network, so
there are describles for recoverying the failure in the multi-ring
interconnection sencrios in the following sections .
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 RFC-2119.
OAM: Operations, Administration, Maintenance
LSP: Label Switched Path.
TLV: Type Length Value
P2MP:Point to Multi-Point
P2P:Point to Point
PSC:Protection Switching Coordination
SD:Signal Degrade
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SF:Signal Fail
RDI:Remote Defect Indication
SPME:Sub-Path Maintenance Entity
MPLS-TP:Multi-Protocol Label Switching Transport Profile
ME: Maintenance Entity
MEP:MEG End Point
ACH: Associated Channel Header
CC-V: Contunuity Check-Verification;
3. recovery mechanisms
This following sections propose different mechanisms that may be used
to protect traffic that traverses multiple rings in the different
interconnection scenarios.
3.1. recovery mechanism for Dual-node interconnected-ring
Under the interconnected-ring scenrio just as figure 1,multi-ring
traffic will be transported by interconnection link(LSR C-LSR
6).protecting against a failure on the interconnection link could be
based on 1:1 linear protection of the segment from LSR-A to LSR-6 by
using the protection path LSR-A to LSR-F to LSR-6. Alternatively, an
end-to-end protection path(LSR-C to LSR-2 through D-E-F-5-4-3) could
be used to protect all traffic. For the two alternatives, they both
have different advantage and disadvantage. 1:1 linear segment
protection may be faster than end-to-end protection. but when the
interconnection node(LSR-A or LSR-6) has a failure, it maybe need
another protection solution to recovery it. but end-to-end protection
may protect one or multiple failures on multi-ring working path.in
specially, it may protect the failure of interconnection node. .
3.2. recovery mechanism for Chained interconnected-ring
For the chained interconnected-ring scenrio, if the interconnection
nodes(LSR-A and LSR-F) or the shared link(LSR-A-LSR-F) have failures,
protecting each single ring will fail to provide recovery of the
failure, so the affected multi-ring traffic should be protected by an
end-to-end protection path. .
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3.3. recovery mechanism for Dual-node and Single-node mixed
interconnected-ring
For the mixed interconnected-ring scenrio, As the single-node
interconnection scenario should be avoided. if we only consider
segment protection between two rings, the solution is the same as
dual-node interconnected-ring. .
3.4. recovery mechanism for Dual-node and Chained mixed interconnected-
ring
. for the mixed interconnected-ring scenrio, each interconnection
nodes or shared interconnection link will be protected by setting up
segment protection path seperately. in addition, it may still use end
to end multi-ring protection path to protect multiple interconnection
nodes or shared interconnection link failure.
3.5. recovery mechanism for Single-node and Chained mixed
interconnected-ring
for the mixed interconnected-ring scenrios, As the single-node
interconnection scenario should be avoided. if we only consider
segment protection between two rings, the solution is the same as
chained interconnected-ring.
3.6. recovery mechanism for Dual-node ,Single-node and Chained mixed
interconnected-ring
for the mixed interconnected-ring scenrios, As the single-node
interconnection scenario should be avoided. here we can consider the
protection solution maybe like solution of dual-node and chained
mixed interconnected-ring scenario.
4. Security Considerations
TBD
5. IANA Considerations
TBD.
6. Acknowledgments
TBD .
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7. References
7.1. Normative References
[RFC 5654]
IETF, "IETF RFC5654(MPLS-TP requirement)", September 2009.
[RFC 5921]
IETF, "IETF RFC5654(MPLS-TP framework)", July 2010.
[RFC 6372]
N. Sprecher, A. Farrel, "Multiprotocol Label Switching
Transport Profile Survivability Framework",
September 2011.
[RFC 6378]
S. Bryant, N. Sprecher, A. Fulignoli Y. Weingarten, "MPLS
transport profile Linear Protection", September 2011.
7.2. Informative References
[MPLS-TP Ring Protection]
Y. Weingarten, "Multiprotocol Label Switching Transport
Profile Ring Protection", Sep 2011.
7.3. URL References
[MPLS-TP-22]
IETF - ITU-T Joint Working Team, "", 2008,
<http://www.example.com/dominator.html>.
Authors' Addresses
Liu Guoman
ZTE Corporation
No.50, Ruanjian Road, Yuhuatai District
Nanjing 210012
P.R.China
Phone: +86 025 52871606
Email: liu.guoman@zte.com.cn
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Yaacov Weingarten
34 Hagefen St Karnei
Shomron 44853
Israel
Phone: +972-9-775 1827
Email: wyaacov@gmail.com
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