draft-rkhd-mpls-tp-sd-00

1. draft-rkhd-mpls-tp-sd-00 IETF 79 November 2010 Ehud Doron (ehudd@orckit.com) Rafi Ram (rafir@orckit.com) Masahiro Daikoku (ms-daikoku@kddi.com)

2. 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

3. Server MEP informed with Signal Degrade Server MEP informed with Signal Degrade SD notification is sent to end points of all affected tunnels SD notification is sent to end points of all affected tunnels Signal Degrade identification and notification Signal Degrade condition detected by PHY • Signal Degrade indication from PHY to server MEP • Server MEP inform LERs of all effected LSPs with SD condition • Allows MPLS-TP protection mechanisms to act upon EP C SD EP a EP B EP D

4. 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

5. 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

6. 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

7. 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 conditions 2. 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

8. 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 firstand then SD-W, there is no change of state • If SD-W occurs firstand then SD-P, there is no change of state

9. Next Steps • Add section of SD BER for various transport technologies and applications • Address any comments • Republish

10. Questions ? Comments ?