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MPLS –TP Fault OAM

draft-ietf-mpls-tp-fault-02

George Swallowswallow@cisco.comIETF78 July 2010

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Major Changes

Message formatDropped use of ACH-TLVs

Extended flag fields

Replaced LDI message with an “LDI Flag” on the AIS message

Added IANA Section

Added Security Section

General editing

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Dropped use of ACH-TLVsAfter talking with many hardware engineers, decided that these were not particularly silicon friendly

Important stuff for hardware is in fixed locations

Moved information into TLVs internal to the message

These can be stored for examination by software or punted up to software

Extended flag fieldsAdded another flag, which left only two, so changed format to allow for eight

Could allow for message format alignment with other drafts

Message format

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Link Down Indication

Replaced LDI message with an “LDI Flag” on the AIS message

LDI is only need when CC is running slowlyIf CC is running fast (detect time ~500 ms or less) then LDI is treated just like AIS

Semantics and the procedures remain the same

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Link Down Indication (LDI)

Setting the LDI flag is driven from the APS state

LDI flag must be set whenever the server layer enters the unavailable state

When LDI is received by an MPLS-TP LSP’s MEP it is used to

Suppresses alarms due to any CC failure – just like AIS

May be used to trigger path protection

e.g. CC is running slowly and no CC failure has occurred

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AIS / LDI Fault Generation

Client LSP

Server Working LSP

Server Protection LSP

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Example 1: An unprotected link

Server Path is unprotected

Control function tells Server MEP W to set LDI flag when generating AIS messages

Server Path WServer Path WServer MEP WServer MEP W

Client PathClient Path

Server APS/Control

Server APS/Control

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Example 2: Both Working and Protection are Up

CC functions are reporting that both W and P are up

APS is in the Normal State

Control Function tells both MEPs to clear the LDI flag when generating AIS messages

Server LSP PServer LSP P

Server LSP WServer LSP W

Server MEP PServer MEP P

Server MEP WServer MEP W

Client PathClient Path

Server APS/Control

Server APS/Control

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Example 3: Protection Up, Working Fails

Server LSP W fails, Server MEP W begins sending AIS with LDI = 0

APS / Control Function moves selector to Protection LSP

AIS ceases to be inserted in Client LSP

APS enters Protecting State, Control Function tells Server MEP P to set LDI flag (= 1) when generating AIS messages

Server LSP PServer LSP P

Server LSP WServer LSP W

Server MEP PServer MEP P

Server MEP WServer MEP W

Client LSPClient LSP

X

Server APS/Control

Server APS/Control

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ACH Codepoint

An ACH Codepoint was requested through the early allocation procedures

The codepoint has been assigned 0x0058 Fault OAM (TEMPORARY - expires 2011-07-16)

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Next Steps

Add a more complete section about setting LDI Flag

Address any comments

Republish

Request last call