MPLS Working Group G. Liu
Internet-Draft ZTE Corporation
Intended status: Informational Y. Weigarten
Expires: April 22, 2013
M. Daikoku
T. Maruyama
KDDI Corporation
October 19, 2012
MPLS-TP protection for interconnected rings
draft-liu-mpls-tp-interconnected-ring-protection-03
Abstract
The requirements for MPLS Transport Profile include a requirement
(R93) that requires that MPLS-TP must support recovery mechanisms for
a network constructed from interconnected rings that protect user
data that traverses more than one ring. In particular, this includes
protecting against cases of failure at the ring interconnect nodes
and links. This document presents different configurations of
interconnected rings and special mechanisms to address the recovery
of ring-interconnect nodes and links. .
This document is a product of a joint Internet Engineering 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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. This document may not be modified,
and derivative works of it may not be created, and it may not be
published except as an Internet-Draft.
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material or to cite them other than as "work in progress."
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This Internet-Draft will expire on April 22, 2013.
Copyright Notice
Copyright (c) 2012 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
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described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions used in this document . . . . . . . . . . . . . . 8
3. recovery mechanism . . . . . . . . . . . . . . . . . . . . . . 9
3.1. recovery mechanism for Dual-node interconnection . . . . . 9
3.2. recovery mechanism for Chained interconnection . . . . . . 11
4. Security Considerations . . . . . . . . . . . . . . . . . . . 12
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . . 12
7.3. URL References . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
This document describes different interconnected ring scenarios and a
few special solutions to protect against the failure of the ring-
interconnect nodes and links. there are three common interconnection
scenarios that we will address in this document:
Dual-node interconnection - when the two rings are interconnected by
two nodes from each ring (see Figure 1);
Single-node interconnection - when the connection between the two
rings is through a single node (see Figure 2).As the interconnnection
node(LSR-A) is a single-point of failure, This configuration should
be avoided in real networks;
Chained interconnection - 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. many
interconnection scenarios could be existed in the same scenario, they
will be mixed interconnection scenario:
Dual-node and single-node mixed interconnection- when there exist a
multi-ring traffic which traveres more than two ring. two of these
rings are dual-node interconnection. while another two are single-
node interconnection (see figure 5);
Dual-node and chained mixed interconnection-when there exist both
dual-node interconnection and chained interconnection in this
scenario (see figure 4);
single-node and chained mixed interconnection-when there exist both
single-node interconnection and chained interconnection in this
scenario(see figure 6);
Dual-node, single-node and chained mixed interconnection-when there
exist all three interconnection scenrios in this scenario 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 traffic, it will be across more than one ring just
like above seven scenarios. if a failure happens on a multi-ring
path, quick recovery is necessary requirement for multi-ring traffic.
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
PSC:Protection Switching Coordination
SD:Signal Degrade
SF:Signal Fail
MPLS-TP:Multi-Protocol Label Switching Transport Profile
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3. recovery mechanism
In the following subsections we propose different mechanisms that may
be applied for traffic recovery in the different interconnection
scenarios. In general, it is possible to provide protection against
the failure of a ring node/link by using the single-ring protection
mechanism. These cases are out of scope for this document. It is
also possible to configure an end-to-end protection to protect the
entire working path across all of the interconnected rings. However,
this protection scheme does not scale very well. Therefore, we need
to consider special mechanisms to address recovery from failures of
the interconnecting nodes and links
3.1. recovery mechanism for Dual-node interconnection
Under this scenario , when interconnection link(LSRA-LSR6) has a
failure as shown in figure 8. it is possible use 1:1 linear
protection mechanism to protect the failure of segment(LSRA-LSR6) by
using one of the protection paths (LSRA-LSRF-LSR5-LSR6 or LSRA-LSRF-
LSR6 or LSRA-LSR5-LSR6) .
/LSR\******/LSR\******/LSR\x||x/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
|| failure
Figure 8
When the interconnection node(LSRA or LSR6) detects a SF or SD on the
interconnection link(LSRA-LSR6), LSRA or LSR6 will send SF or SD
failure message to its peer node. Then it switchs the multi-ring
traffic from the working path to its corresponding protection path to
another end point(LSRA or LSR6) of the segment . when the peer node
(LSR6 or LSRA) receives the traffic packet from its protection
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protection path, it will POP the outer label of protection tunnel and
return back to the original working tunnel(LSRA-LSRB-LSRC or LSR6-
LSR1-LSR2) of another ring(ring 1 or ring 2) to transport the multi-
ring traffic.
when interconnection node(LSRA or LSR6) has a failure as shown in
figure 9. the end node of the segment detects the failure of the
interconnection node, it should send failure messge to the backup
interconnection node(LSRF or LSR5) to active the protection path that
goes to the backup interconnection node(LSRF or LSR5) to trasnport
the multi-ring traffic. at the same time, the backup interconnection
node should active its corresponding protection path that goes to
another primary interconnection node(LSR6 or LSRA).Then the multi-
ring traffic should return back to the original working path to be
transported in another primary interconnection node..
##
/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
## node failure
Figure 9
for example , LSRC detects a failure on the interconnection node
LSRA. it will send the failure message to notify the backup
interconnection node LSRF to switch over to the protection path(LSRC-
LSRD-LSRE-LSRF) to transport the multi-ring traffic.at the same time,
LSRF should active its corresponding protection path that goes to
another primary interconnection node LSR6 to transport the multi-ring
traffic.The corresponding protection path may be one of the two
paths(LSRF-LSR5-LSR6 or LSRF-LSR6). Then the multi-ring traffic will
be transported by its original working path(LSR6-LSR1-LSR2) to the
exit node LSR2.
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3.2. recovery mechanism for Chained interconnection
For this scenario , when only a failure is detected on the
interconnection link. Since the failure should not affect the multi-
ring traffic. no action is taken. when a failure happens on the
segment of the multi-ring path just as shown in figure 10. The end
node of the segment detects the failures, it will active the
protection path that goes to the backup interconnection node to
transport the multi-ring traffic. After the backup interconnection
node receives the failure message , it will active its corresponding
protection path that goes to the exit node of another ring to
trasnport the multi-ring traffic.
___ ___ ___ ___ ___
/LSR\**||**/LSR\******/LSR\*****/LSR\******/LSR\
\_C_/ \_B_/ \_A_/ \_1_/ \_2_/
* x *
* Ring #1 || Ring #2 *
_*_ ___ _x_ ___ _*_
/LSR\ /LSR\ /LSR\ /LSR\ /LSR\
\_D_/******\_E_/******\_F_/*****\_4_/******\_3_/
*** physical link
xxx shared link
|| failure
Figure 10
for example, there are failures on both link(LSRC-LSRB) and (LSRA-
LSRF) at the same time as shown in figure.10. when LSRC detects or is
notified of the failures on both the segment of the working path and
the interconnection link. so it will send a failure message to the
backup interconnection node LSRF, Then LSRF will active its
corresponding protection path(LSRF-LSR4-LSR3-LSR2) of ring 2 to
transport the multi-ring traffic.
(Editor's note:should supply text that describes protection against
the failure of interconnection node in the chained interconnection
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scenario in the future. welcome all experts provide good solution for
the failure)
4. Security Considerations
TBD
5. IANA Considerations
TBD.
6. Acknowledgments
TBD .
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,
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<http://www.example.com/dominator.html>.
Authors' Addresses
Guoman Liu
ZTE Corporation
No.50, Ruanjian Ave, Yuhuatai District
Nanjing 210012
P.R.China
Phone: +86 025 88014227
Email: liu.guoman@zte.com.cn
Yaacov Weingarten
34 Hagefen St Karnei
Shomron 44853
Israel
Phone: +972-9-775 1827
Email: wyaacov@gmail.com
Masahiro Daikoku
KDDI Corporation
Garden Air Tower,Iidabashi, Chiyoda-ku
Tokyo 102-8460
Japan
Email: ms-daikoku@kddi.com
Takeshi Maruyama
KDDI Corporation
Garden Air Tower,Iidabashi, Chiyoda-ku
Tokyo 102-8460
Japan
Email: ta-maruyama@kddi.com
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