Inter-Region TE

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Inter-Region TE

• Arthi Ayyangar
• JP Vasseur

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Region

• A region is an IGP area (level) or an AS or a
  sub-AS or a different routing realm (for overlay)
• A region can also be a domain, for example, for
  optical or SDH sub-networks

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Whats New?

• Single end-to-end LSP spanning multiple regions
• Versus
• Multiple LSP pieces, one in each region,
  stitched or nested to carry the end-to-end
  multi-region LSP
• Scheme is inherently recursive (areas within
  sub-ASes within ASes, etc.)
• This improves scalability relative to having a
  single end-to-end LSP

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Consequences

• Each region can decide itself whether to stitch
  or nest (depending on technology)
• If nesting, each region can decide if the FA LSP
  is pre-provisioned or dynamically set up
• Crankback stays within a region whenever possible
• Internal topology of any region is hidden from
  other regions

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Consequences (2)

• Each region can apply its own re-optimization
  policies
• Each region can have its own protection and
  restoration scheme

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Comments?

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