draft-liu-pwe3-mpls-tp-p2mp-pw-protection-02:
p2mp pw protection for MPLS-TP network
Author(s): Yu jinghai, Guoman Liu
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 for the p2mp traffic...
PWE3 Working Group G. Liu
Internet-Draft J. Yu
Intended status: Informational ZTE Corporation
Expires: June 15, 2013 December 12, 2012
p2mp pw protection for MPLS-TP network
draft-liu-pwe3-mpls-tp-p2mp-pw-protection-02
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 for the p2mp traffic in rfc6718 , it
must have a return path to coordinate the switch state to select the
same path to receive and send the traffic packet.As there exists the
above problem statement,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. 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and derivative works of it may not be created, and it may not be
published except as an Internet-Draft.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."
This Internet-Draft will expire on June 15, 2013.
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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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Table of Contents
1. Problem statement . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . . 3
3. protection solution . . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . . 8
7.3. URL References . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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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 leaf node and root node . So it costs more
configuration and maintenece . While this document describes a kind
of protection solution for p2mp traffic without return path, IP
forwarding capability and control plane.
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 RFC2119.
OAM: Operations, 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
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3. protection solution
This section will describe a protection solution for p2mp pw
path,which uses one leaf node as protector node of another leaf
node.The two leaf nodes protect each other.in addtion, In order to be
easy to access to CE node, It should set up backup node to directly
access to CE node. If the backup node is still a leaf node of the
p2mp pw path , the protector node and the backup node are the same
node. in addtion, A bidirectional p2p pw should be configurated
between the protected node, the backup node and the protector node
.Just as the following figure 1:
___ ___ ___
*/LSR\ ********* /LER\********** /CE1\
* \ A / \_1_/ + \___/
__ * - - + +
/LER\* . _+_ +
/LER\+
\_O_/* . \_2_/+
* . + +
* ___ _+_ + ___
* /LSR\ /LER\ + /CE3\
* \ B / ********** \_3_/*********** \___/
- -
***** working pw
+++++ protection pw
Figure 1
LER0 is the root node of a p2mp pw, LER1 and LER3 are leaf nodes of
the p2mp pw. LER2 is backup node for LER1 and LER3. When protected
node LER1 or LER3 has the failure, its backup node LER2 will replace
a protected node LER1 or LER3 to transmit the protected p2mp traffic
packet to CE1 or CE3. If CE1 or CE3 detects a failure on its working
access link(*), it will select protection access link(+) to receive
the traffic.Just as the following figure 2,.
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___ ___ ___
*/LSR\ ********* /LER\****X***** /CE1\
* \ A / \_1_/ + \___/
__ * - - X +
/LER\* . _+_ +
/LER\+
\_O_/* . \_2_/+
* . + +
* ___ _+_ + ___
* /LSR\ /LER\ + /CE3\
* \ B / ********** \_3_/*********** \___/
- -
***** working pw
+++++ protection pw
X failure
Figure 2
If LER1 has a failure, CE1 and LER2 MUST detect the failure by OAM or
other checking mechanism. 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 traffic packet
of the p2mp pw to transmit to LER2 by pre-configured p2p protection
pw. Then LER2 sends the traffic packet of the p2mp pw to CE1 by the
protection access link(LER2-CE1).At the same time, When CE1 detects
the failure on its working access link(LER1-CE1), it must switch to
receive the traffic packet from its protection access link(LER2-CE1).
If only a failure is detected on the working access link, such as
access link(LER1-CE1) in the following figure 3:
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___ ___ ___
*/LSR\ ********* /LER\****X***** /CE1\
* \ A / \_1_/ + \___/
__ * - - + +
/LER\* . _+_ +
/LER\+
\_O_/* . \_2_/+
* . + +
* ___ _+_ + ___
* /LSR\ /LER\ + /CE3\
* \ B / ********** \_3_/*********** \___/
- -
***** working pw
+++++ protection pw
X failure
Figure 3
when CE1 and LER1 detect a failure on the working access link(LER1-
CE1), LER1 firstly notify its backup node LER2 of the egress AC
failure by pw status message[1]. Then LER1 will send the protected
traffic packet to LER2 by protection p2p pw between LER1 and LER2.
LER2 will transmit the traffic packet to CE1 by its protection access
link(LER2-CE1). At the same time, CE1 will switch to receive the
traffic packet from its protection access link(LER2-CE1).
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 that its backup node will transmit the protected
traffic packet to the protected node.For example, The following
figure 4 describes the protection scenario.
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___ ___ ___
*/LSR\ *****X**** /LER\********* /CE1\
* \ A / \_1_/ + \___/
__ * - - + +
/LER\* . _+_ +
/LER\+
\_O_/* . \_2_/+
* . + +
* ___ _+_ + ___
* /LSR\ /LER\ + /CE3\
* \ B / ********** \_3_/*********** \___/
- -
***** working pw
+++++ protection pw
X failure
Figure 4
When a failure happens on the branch working pw path(LER0-LSRA-LER1),
the protected node LER1 will detect the failure and notify 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 traffic packet of the p2mp pw to send it to the backup node LER2
firstly. Then LER2 continue to transmit the traffic packet to the
protected node LER1. CE1 will still receive the traffic packet on
its working access link(LER1-CE1)
4. Security Considerations
TBD
5. IANA Considerations
TBD.
6. Acknowledgments
TBD .
7. References
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7.1. Normative References
[RFC 5654]
IETF, "IETF RFC 5654(MPLS-TP requirement)", September 2009.
[RFC 5921]
IETF, "IETF RFC 5654(MPLS-TP framework)", July 2010.
[RFC 6478]
IETF, "IETF RFC 6478(Pseudowire Status for Static
Pseudowires)", May 2012.
[RFC 6718]
IETF, "IETF RFC 6718(Pseudowire Redundancy)", August 2012.
7.2. Informative References
[draft-ietf-pwe3-redundancy-bit-08]
Praveen Muley, Mustapha Aissaoui, "Pseudowire Preferential
Forwarding Status Bit", September 2012.
7.3. 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 Road, Yuhuatai District
Nanjing 210012
P.R.China
Phone: +86 025 88014227
Email: liu.guoman@zte.com.cn
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Jinghai Yu
ZTE Corporation
No.50, Ruanjian Road, Yuhuatai District
Nanjing 45241
P.R China
Phone: +86 025 88014226
Email: yu.jinghai@zte.com.cn
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