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LDP Extensions for Pseudo Wire (PW) Transfer in an MPLS-TP Network

draft-bao-pwe3-pw-transfer-00.txt

Yuanlin Bao: bao.yuanlin@zte.com.cnLizhong Jin: lizhong.jin@zte.com.cnRuiquan Jing: jingrq@ctbri.com.cn

Xiaoli Huo: huoxl@ctbri.com.cn

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Background• Merged the following drafts

▪ draft-bao-mpls-tp-path-transfer-reqs-00.txt– presented on the 77th meeting– disscussed in MPLS mailing list

▪ draft-fuxh-mpls-tp-transfer-framework-00.txt– presented on the 77th meeting

▪ draft-bao-pwe3-pw-transfer-ldp-ext

• Contents of this draft▪ discusses the advantage compared with MBB▪ LDP extensions and procedures

– the PW Transfer Capability TLV– PW Ownership Transfer TLV– S-PE TLV and Sub-TLV (draft-ietf-pwe3-segmented-pw)

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Comparison with Make Before Break(MBB)

Potential influence MBB PW Transfer

FEC label bindingDue to traffic switching from old LSP to new LSP, FEC label binding will be modified

No modification

PW LSP bindingDue to traffic switching from old LSP to new LSP, PW LSP binding will be modified

No modification

Extra data plane resource

Extra resource is needed for new LSP creation.

Need not

Batch operationUnavailble, because old LSP has to be deleted by MP. Operator will repeat the tedious operation.

Available and efficient

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Requirements• Requirements– Requirement 55 of RFC5654– draft-ietf-ccamp-mpls-tp-cp-framework-03.txt• Requirement 47• Section 5.3.3

– Requirements in RFC5493 also apply

• Additional requirements– PW attributes MUST not be changed– PW transfer MUST be independent of LSP– Support partial MS-PW segments transfer

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• PW Transfer Capability TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1|0|PW Transfer Capability(TBD)| Length (= 1) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |1| Reserved | +-+-+-+-+-+-+-+-+

– Carried in LDP Initialization Message (RFC5561)– Negotiating the PW transfer capability between LDP Peers

• PW switching point TLV (S-PE TLV) and Sub-TLV• defined in draft-ietf-pwe3-segmented-pw• used to carry the data plane PW path

LDP Extension

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• PW Ownership TransferTLV• Carried in LDP Label Mapping and Notification message

0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|0| PW Transfer | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |POT| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

POT (2 bits): PW Ownership Transfer 1 - PW ownership transfer from MP to CP 2 - PW ownership transfer from CP to MP

LDP Extension (cont.)

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MP to CP Transfer Procedure(SS-PW)

• T-PEs– Negotiate PW transfer capability– Send/Receive Label Mapping message with PW Transfer TLV– Create/Maintain PW signaling state in CP

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MP to CP Transfer Procedure (MS-PW)

• T-PEs– Perform all the procedures in MP2CP SS-PW transfer plus

• encoding PW path into S-PE TLV and Sub-TLV

• S-PEs– create PW LDP signaling state in CP– decode the S-PE TLV and Sub-TLV to find the next hop– forward Label Mapping message to the next hop

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CP to MP Transfer Procedure• T-PEs

– send CP2MP PW transfer Notification message– delete T-LDP session according to the local policy

• S-PEs– forward Notification message– delete T-LDP session according to the local policy

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Next Steps

• Refine the document according to the feedback of this meeting and mailing list.

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Comments ?

Thank you !