1. MPLS-TP Alarm Suppression tool
draft-fulignoli-mpls-tp-ais-lck-tool-01.txt
MPLS WG, 75th IETF - Stockholm, Sweden

2. Authors Annamaria Fulignoli <annamaria.fulignoli@ericsson.com>
Yaacov Weingarten
Nurit Sprecher

3. Aim of the draft
To define an MPLS-TP OAM mechanism to meet the two requirements for Alarm Suppression functionalities:
Alarm Reporting
Lock Reporting

4. Alarm Indication Signal behaviour [1/2]
Alarm Reporting function relies upon an alarm Indication Signal ( AIS) message.
A MEP, upon detecting a signal fail condition, can transmit AIS packets in a direction opposite to its peer MEP to notify the fault condition to its client (sub-)layer MEPs.
The periodicity of AIS packet transmission is fixed at 1 second. The first AIS packet must always be transmitted immediately following the detection of the signal fail condition.
Upon receiving a packet with AIS information, a MEP detects an AIS defect condition and suppresses loss of continuity alarms associated with its peer MEP.
AIS defect can contribute to the signal fail condition of the receiving MEPs that may result, in turn, in the transmission of AIS packets to its own MPLS-TP client MEPs

5. Alarm Indication Signal behaviour [2/2]
C detects a failure on the B-C Link that affects the A-D LSP
AIS
C sends an AIS to D on the A-D LSP

6. Lock Reporting
Lock reporting function relies upon Lock reporting information (LCK ) message to notify an administartive traffic locking condition to its client (sub)-layer
The periodicity of LCK packets transmission is fixed to one second. The first LCK packet must always be transmitted immediately following the administrative /diagnostic action.
Upon receiving a packet with LCK information, a MEP detects a LCK defect condition and suppresses loss of continuity alarms associated with its peer MEP.
A MEP that detects a LCK defect can in turn transmit LCK packet to its MPLS-TP client MEPs.
Requirements and procedure for Lock Reporting are still under discussion in draft-ietf-mpls-tp-oam-requirement and draft-ietf-mpls-tp- oam-framework. This section of the draft will be aligned according to the final decision

7. Defect

8. Packet format
One packet format, with two different function codes, is defined in order to distinguish among packets with Alarm Indication information and packets with Lock Reporting information.

10. Fault TLV
One or more Fault Location TLV MAY be included, under operator configuration, in the AIS or LCK packet; the DEFAULT mode is not to include it.
When a MEP receives an AIS/LCK with the Fault Location TLV and it is configured to (re)generate the AIS/LCK packet to its client MEPs the following cases can occur:
The MEP is configured to (re)generate AIS/LCK messages with no Fault Location TLV
The MEP is configured to(re)generate AIS/LCK messages with the Fault TLV carrying its own identifier; this can occur when the server and client MEs are under different administrative domains such that the client ME needs to know that the failure is located within that specific server ME (i.e. it is not under its responsibility to recover the failure) but not exactly where, within the server ME, the failure is located
The MEP is configured to (re)generates AIS/LCK messages with the Fault Location TLV copied from the received AIS/LCK message; this is useful when both the server and client MEs are under the same administrative domain so the administrator can quickly identify where is the failure to fix

11. Fault Location TLV format

12. Next Steps
Alignment of LCK behaviour section to the final requirement and framework
Alignment of Fault TLV with Node/Interface identifier (definition in progress in draft-swallow-mpls-tp-identifiers)
Request adoption as working group draft

13. QUESTIONS ?
THANK YOU

14. Appendix: Lock requirements and behavior open issue
LCK packets sent only in the direction opposite to its peer MEP (from OAM framework team) A D B C
LCK
C sends an LCK to D on the A-D LSP
The B-C Link is locked at C: this condition affects the A-D LSP

15. Or LCK packets behaviour as per G.8021 (from OAM framework team)D B C
LCK
B sends an LCK to D on the A-D LSP
The B-C Link is locked at B: this condition affects the A-D LSP

16. Lock Notification and Reporting (from OAM framework team)B C
The B-C Link is locked at B
LCK
C sends an LCK to D on the A-D LSP
LCN
B sends a Lock notification to C on the B-C MPLS-TP Section
C is notified that the B-C Link is locked at B: this condition affects the A-D LSP