draft-rkhd-mpls-tp-sd-00

IETF 78 July 2010

Rafi Ram( rafir@orckit.com)Masahiro Daikoku( ms-daikoku@kddi.com)

Problem Statement

• Provide carrier view guide lines for signal degrade detection for protection triggering

• Suggest SD detection approach originating from server MEP sub-layer

• Provide end-to-end view on architecture of :– Signal degrade detection – Signal degrade condition notification– Signal degrade consideration in protection switching

Guide Lines for SD Detection )1(

• Method MUST not disrupt the forwarded services – e.g. add delay or jitter to real time traffic

• Criterion for determining signal degrade MUST be agnostic to :– Length and rate of frames transmitted– Traffic class and drop precedence marking of

frames– Link congestion level

Guide Lines for SD Detection )2(

• Method SHOULD be able to detect low BER condition

• Method SHOULD have low miss-detection and false alarm probabilities

• Method SHOULD be agnostic to number of LSPs or PWs forwarded over the link

• Method for determining signal degrade is RECOMMENDED not to require transmission of traffic exclusively dedicated for this purpose

Examples for SD Detection Methods

• 1GE PCS : Measurement of rate of 10bit code violations and dispersion errors

• 10GE PCS : Measurement of rate of errored 66bit block headers

• Note : These examples work as long as the layer carrying the information used for SD detection is not terminated in between two

MPLS-TP transport entities

SD Condition Notification

• A server MEP identifying SD condition should advertise this condition to the MPLS entity handling the protection

• Propose addition of a new fault message type “Link Condition Indication” )LCI(

• The LCI message can have the following impairment flags :)1( Link performance is reduced )i.e. signal degraded()2( Link is congested)3( Link rate is reduced

Note : Using the existing LDI for conveying SD may have the following drawbacks :1. It does not allow the flexibility to report of various impairment conditions2. Need to differentiate between “link down” condition )equivalent to SF( and “link reduced”

)equivalent to SD(, since for APS state machine SF has higher priority than SD

SD Consideration for Protection Switching

• SD has a lower protection priority than SF-W, but higher than MS

• SD-P and SD-W have similar protection priority :– If SD-P occurs first and then SD-W, there is

no change of state– If SD-W occurs first and then SD-P, there is

no change of state

Next Steps

• Add section of SD BER for various transport technologies and applications

• Address any comments• Republish

Questions ? Comments ?