Internet DRAFT - draft-liu-mpls-tp-interconnected-ring-protection
draft-liu-mpls-tp-interconnected-ring-protection
MPLS Working Group G. Liu
Internet-Draft ZTE Corporation
Intended status: Informational Y. Weigarten
Expires: April 21, 2014
M. Daikoku
T. Maruyama
KDDI Corporation
October 18, 2013
MPLS-TP protection for interconnected rings
draft-liu-mpls-tp-interconnected-ring-protection-05
Abstract
The requirements for MPLS Transport Profile include a requirement
(R93) that requires 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 scenario of
interconnected rings and special mechanism to address recovery of the
failure 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.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 21, 2014.
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Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 6
3. Recovery mechanism . . . . . . . . . . . . . . . . . . . . . 7
3.1. Recovery mechanism for Dual-node interconnection . . . . 7
3.2. Recovery mechanism for chained interconnection . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Normative References . . . . . . . . . . . . . . . . . . 11
7.2. URL References . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction
This document describes different interconnected ring scenario and a
few special mechanisms 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 scenario should be
avoided in real network;
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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: Dual-node interconnection scenario
___ ___ ___ ___
/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: Single-node interconnection scenario
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___ ___ ___ ___ ___
/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 interconnection link
Figure 3: chained interconnected scenario
Considering a 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 exists a
multi-ring traffic which traveres more than two rings. 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);
___
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/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: Dual-node and chained mixed interconnect scenario
___
/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: Dual-node and single-node mixed interconnect scenario
___
/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_/
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*** physical link
xxx interconnection link
Figure 6: Chained and single-node mixed interconnect scenario
___
/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: Dual-node,chained and single-node mixed interconnect
scenario
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
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SF:Signal Fail
MPLS-TP:Multi-Protocol Label Switching Transport Profile
3. Recovery mechanism
In the following subsection, It proposes different mechanism that may
be applied for traffic recovery for different interconnection
scenario. In general, It may be possible to provide protection
against the failure of a ring node/link by using a single-ring
protection mechanism. These cases are out of scope for this
document.At the same time, It is also possible to configure an end-
to-end protection path to protect a multi-ring traffic which will
across multi-ring. While this protection mechanism does not scale
very well. We need to consider special mechanism 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 tunnels (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: interconnection link failure for dual-node interconnection
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 they push the multi-ring
traffic into its corresponding protection tunnel to another end
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point(LSRA or LSR6) of the segment . When the peer node (LSR6 or
LSRA) receives the traffic packet from its protection tunnel, 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 the 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 its corresponding
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) of another ring.Then the multi-ring traffic should
return back to the original working path to be transported in another
ring.
##
/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: interconnection node failure for dual-node interconnection
For example , When LSRC directly detects or is informed of a failure
on the interconnection node LSRA. it will send a failure message to
notify the backup interconnection node LSRF to active its protection
path(LSRC-LSRD-LSRE-LSRF) to transport the multi-ring traffic.At the
same time, When LSRF receives the failure message from LSRC ,it
should still 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 another
peer 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 by interconnection node. since the failure
should not affect the multi-ring traffic. no action is need to be
taken. When a failure happens on the segment of the multi-ring path
and the interconnection link at the same time ,just as shown in
figure 10. The end node of the multi-ring path directly detects or
is informed of the two failures, Then 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 end node of another ring
___ ___ ___ ___ ___
/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 interconnection link
|| failure
Figure 10: interconnection link failure for chained interconnected
scenario
For example, there are a failure 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 segment failure on both the segment of ring 1 and
the interconnection link. 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.
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When a interconnection node has a failure for the chained
interconnection scenario, both peer node of the two rings will detect
the failure by segment OAM. So they should switch into the multi-
ring protection path to transport the multi-ring traffic.
___ ___ _##_ ___ ___
/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 interconnection link
## node failure
Figure 11: interconnection node failure for chained interconnected
scenario
Just as the failure scenario in figure 11. When an interconnection
node LSRA has a failure, the peer node(LSRC and LSR2) of ring 1 and
ring 2 must detect the node failure by segment OAM , Then they will
active protection switch and transport the protected multi-ring
traffic by its corresponding protection path(LSRC-LSRD-LSRE-LSRF-
LSR4-LSR3-LSR2) to LSR2. Then the protected traffic will return back
to the original working path to be transported.
4. Security Considerations
TBD
5. IANA Considerations
TBD.
6. Acknowledgments
TBD .
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7. References
7.1. Normative References
[RFC5654] IETF, "MPLS-TP requirement ", September 2009.
[RFC5921] IETF, "MPLS-TP framework ", July 2010.
[RFC6372] N. Sprecher, A. Farrel, ., "Multiprotocol Label Switching
Transport Profile Survivability Framework", September
2011.
[RFC6378] S. Bryant, N. Sprecher, A. Fulignoli Y. Weingarten, .,
"MPLS transport profile Linear Protection", September
2011.
[RFC6974] Y. Weingarten,S. Bryant,D. Ceccarelli, ., "Applicability
of MPLS Transport Profile for Ring Topologies", July 2013.
7.2. URL References
[MPLS-TP-22]
IETF - ITU-T Joint Working Team, 2008,
<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
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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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