MPLS-TP Survivability Framework

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MPLS-TP Survivability Framework

• Nurit Sprecher / Nokia Siemens Networks
• Adrian Farrel / Old Dog Consulting
• Vach Kompella / Alcatel-Lucent

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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.

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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.

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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

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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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Questions
7
Thanks
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Functional ArchitectureElements 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

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Functional ArchitectureElements 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

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Functional ArchitectureLevels 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

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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