1. MPLS-TP Survivability Framework
Nurit Sprecher / Nokia Siemens Networks
Adrian Farrel / Old Dog Consulting
Vach Kompella / Alcatel-Lucent

2. Survivability
Survivability is the network ability to restore traffic and recover from ‘failed’ or ‘degraded’ transport entities (links or nodes).
Survivability plays a critical factor in the delivery of reliable services in transport networks.

3. Scope and Objectives
Provide a framework for MPLS-TP-based survivability
Introduce the functional architecture
Describe existing mechanisms available to provide protection within MPLS-TP networks
Highlight areas where new work is required
Identify which mechanisms should be extended
Identify which new mechanisms should be specified
Make use of the recovery terminology defined in RFC4427 (which draws on G.808.1).
Refer to the requirements specified in draft-jenkins-mpls-mplstp-requirments-00.txt.
Use similar principles of the recovery schemes as those defined and analyzed in RFC 4427 and RFC 4428.

4. Functional Architecture
Define the elements of the functional architecture for survivability
Elements of
Control
Elements of
Recovery
Levels of
Recovery
Mechanisms
for
Recovery
Different combinations of the functional elements can provide different levels of recovery as required in draft-jenkins-mpls-mplstp-requirments-00.txt
Different recovery levels may be used concurrently by a single MPLS-TP transport path for additional resiliency

5. Status and Next Steps
Initial version (00) was posted for the Dublin meeting
Next version is available at
Consolidate the MPLS-TP requirements for survivability
Authors are soliciting comments, feedback and input from WG
Authors plan to continue work on the draft and publish a new draft after the Dublin meeting

6. Questions

7. Thanks

8. Functional Architecture Elements of Control
Recovery actions may be triggered by one or more of the following elements of control:
In-band (i.e. data-plane based) OAM fault management (failure detection, localization and notification)
A network device detecting a network failure
Manual control of an operator
Control plane signaling

9. Functional Architecture Elements of Recovery
MPLS-TP refers to the following quantitative aspects of recovery:
Span recovery
A network segment between two LSRs that are immediately adjacent at the same network layer (e.g. data link, TE link, bundle of TE links, etc.)
Tandem Connection (i.e. segment) recovery
A segment of an LSP (i.e. a sub-path), or one or more segment(s) of a PW
End-to-end recovery

10. Functional Architecture Levels of Recovery
MPLS-TP refers to qualitative levels of survivability functions that can be provided
Dedicated recovery
Shared protection
Extra traffic
Restoration and repair
The level of recovery directly affects the service level provided to the end user in the event of a network failure (in terms of amount of data-lost and recovery time)
There is a correlation between the level of recovery provided and the cost to the network

11. Functional Architecture Mechanisms for Recovery
General mechanisms for recovery, like
Alternate paths
Bypass tunnels
Etc.
Optimized mechanisms for specific topologies
Mesh networks
Ring networks
Recovery in multi-layer or multi-region networking where recovery may be performed at multiple layers or across cascaded recovery domains