Internet DRAFT - draft-liu-pwe3-mpls-tp-p2mp-pw-protection
draft-liu-pwe3-mpls-tp-p2mp-pw-protection
PWE3 Working Group G. Liu
Internet-Draft ZTE Corporation
Intended status: Informational June 09, 2013
Expires: December 11, 2013
p2mp pw protection for MPLS-TP network
draft-liu-pwe3-mpls-tp-p2mp-pw-protection-03
Abstract
The requirements of MPLS-TP in RFC 5654 include a requirement(R63)
that requires MPLS-TP MUST be possible to provide protection for
MPLS-TP data plane without any IP forwarding capability and control
plane.If applying 1:1 protection mechanism for the p2mp traffic in
rfc6718 , it must have a return path to coordinate switch state to
select the same path to receive and send traffic packet.For the above
problem,this document describes a kind of protection solution to
recovery and protect the p2mp traffic under the failure condition.
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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 11, 2013.
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Copyright Notice
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Table of Contents
1. Problem statement . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Protection Mechanism . . . . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. URL References . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Problem statement
According to MPLS-TP requirement(RFC 5654), It requires that MPLS-TP
data plane is independent of control plane and IP forwarding
capability. So it means that MPLS-TP data plane can still work
without control plane and any IP forwarding capability.It must be
essential for unidiretional path including p2p or p2mp path to set up
a return path between any two end nodes . So it costs more
configuration and maintenece . While this document provides a
protection mechanism for p2mp traffic without return path, IP
forwarding capability and control plane.
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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: Operation, Administration, Maintenance
LSP: Label Switched Path.
PW: Pseudowire
P2MP:Point to Multi-Point
P2P:Point to Point
PSC:Protection Switching Coordination
CE:Customer Equipment
LER:Label Edge Router
LSR:Label Switch Router
IP: Interenet Protocol
MPLS-TP:Multi-Protocol Label Switching Transport Profile
ME: Maintenance Entity
MEP:MEG End Point
CE: Customer Equipment
3. Protection Mechanism
This section will describe a protection mechanism for p2mp pw
path,which regards a leaf node as protector node of another leaf node
on the p2mp pw path.The two leaf nodes protect each other.in addtion,
In order to be easy to access to CE node, It should select LER as
backup node which will connect protector node and CE node. If the
backup node is still a leaf node of the p2mp pw path ,in a result,
the protector node and the backup node are the same node. in addtion,
A bidirectional p2p pw should be configurated between the protected
node and the backup node or the protector node , and between the
protector node and the backup node .Just as the following figure 1:
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___ ___ ___
*/LSR\ ********* /LER\########## /CE1\
* \ A / \_1_/ # \___/
__ * - - + #
/LER\* . _+_ #
/LER\#
\_O_/* . \_2_/#
* . + #
* ___ _+_ # ___
* /LSR\ /LER\ # /CE2\
* \ B / ********** \_3_/########### \___/
- -
***** working pw
+++++ protection pw
##### access link
Figure 1: p2mp pw protection configuration topology figure
LER0 is root node of a p2mp pw, LER1 and LER3 are leaf nodes of the
p2mp pw. LER2 is a backup node for LER1 and LER3. When the
protected node LER1 or LER3 has a failure, its backup node LER2 will
replace of the protected node LER1 or LER3 to transmit the protected
p2mp traffic to CE1 or CE2.
If LER1 has a failure, LER2 MUST detect the failure by PW OAM. Then
LER2 will notify its protector node LER3 of the failure by pw status
message[1]. When LER3 receives the failure status message, it will
begin to duplicate the p2mp traffic to send to LER2 by pre-configured
p2p protection pw. Then LER2 sends the p2mp traffic to CE1 by its
access link(LER2-CE1) ,Just as the following figure 2.
___ _X_ ___
*/LSR\ ********* /LER\########## /CE1\
* \ A / \_1_/ # \___/
__ * - - + #
/LER\* . _+_ #
/LER\#
\_O_/* . \_2_/#
* . + #
* ___ _+_ # ___
* /LSR\ /LER\ # /CE2\
* \ B / ********** \_3_/########### \___/
- -
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***** working pw
+++++ protection pw
##### access link
X failure
Figure 2: node failure
When a leaf node detects a failure on its working pw , it will notify
the failure of its backup node or protector node by pw status
message[1]. So its backup node or protector node will transmit the
protected p2mp traffic to the protected node.Just as the following
figure 3.
___ ___ ___
*/LSR\ *****X**** /LER\######### /CE1\
* \ A / \_1_/ # \___/
__ * - - + #
/LER\* . _+_ #
/LER\#
\_O_/* . \_2_/#
* . + #
* ___ _+_ # ___
* /LSR\ /LER\ # /CE2\
* \ B / ********** \_3_/########### \___/
- -
***** working pw
+++++ protection pw
##### access link
X failure
Figure 3: working pw failure
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When a failure happens on the branch working pw path(LER0-LSRA-LER1),
the protected node LER1 will detect the failure and inform the
failure of its backup node LER2 and protector node LER3. Then LER2
and LER3 receive the failure message from LER1 ,LER3 will duplicate
the protected p2mp traffic to send to the backup node LER2 firstly by
its protection pw between LER2 and LER3. Then LER2 sends the traffic
to the protected node LER1 by the protection pw between LER1 and
LER2. At last CE1 will receive the traffic by its access
link(LER1-CE1)
4. Security Considerations
TBD
5. IANA Considerations
TBD.
6. Acknowledgments
TBD .
7. References
7.1. Normative References
[RFC5654] IETF, "IETF RFC5654(MPLS-TP requirement) ", September
2009.
[RFC5921] IETF, "IETF RFC5654(MPLS-TP framework) ", July 2010.
[RFC6478] IETF, "IETF RFC6478(Pseudowire Status for Static
Pseudowires) ", May 2012.
[RFC6718] IETF, "IETF RFC6718(Pseudowire Redundancy) ", August 2012.
[RFC6870] IETF, "IETF RFC6870(Pseudowire Preferential Forwarding
Status Bit) ", February 2013.
7.2. URL References
[MPLS-TP-22]
IETF - ITU-T Joint Working Team, 2008,
<http://www.example.com/dominator.html>.
Author's Address
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Guoman Liu
ZTE Corporation
No.50, Ruanjian Road, Yuhuatai District
Nanjing 210012
P.R.China
Phone: +86 025 88014227
Email: liu.guoman@zte.com.cn
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