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

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.

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.

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

Status and Next Steps Initial version (00) was posted for the Dublin meeting Next version is available at http://www.olddog.co.uk/download/draft-sprecher-mpls-tp-survive-fwk-01a.doc 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

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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

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

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

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