draft-dachille-diverse-inter-region-path-setup-01.txt

1
draft-dachille-diverse-inter-region-path-setup-01.
txt

• A. DAchille dachille_at_coritel.it
• U. Monaco monaco_at_infocom.uniroma1.it
• V. Sharma v.sharma_at_ieee.org
• F. Ricciato ricciato_at_coritel.it
• D. Ali ali_at_coritel.it
• M. Listanti listanti_at_infocom.uniroma1.it

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Joint Selection Approach Overview (1/3)

• Addresses problem of implementing end-to-end
  diverse routing across multi-region networks
• Flexible network model -- applies to any network
  where
• Network topology can be modeled as a conglomerate
  of interconnected regions (OSPF areas, ASs, etc.)
• Border nodes have
• Complete knowledge of intra-region topology
• Summarized info. of inter-region connectivity
  (list of inter-region paths)

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Joint Selection Approach Overview (2/3)

• New RSVP-TE object, Associated Route Object
  (ARO), to support the simultaneous computation of
  the disjoint LSPs
• Records paths of disjoint LSPs during the
  signaling of the first LSP
• The format of the sub-objects included in ARO is
  shown below

ARO Sub-objects
RSVP-TE signaling for JSA
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Joint Selection Approach Overview (3/3)

• Advantages of the disjoint path computation
  scheme are
• Independence from disjoint paths computation
  algo./method
• E.g. Bhandari, Surballe, others,
• No extra signaling/routing load to achieve the
  objective
• Generic method of communicating alternate path
  info.
• Usable in other contexts
• Robustness against trapping topology problem
• Better performance on path selection

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Experimental Results (1/4)

• Comparison of different inter-region routing
  mechanisms
• 1) JSA (ARO) 2) ISPA (RROXRO) 3) Global optimum
• Simulation scenario
• 24 inter-region networks of 3 regions connected
  linearly
• Intra-region topology derived from realistic
  router-level ISP topologies (abovenet, ebobe,
  tiscali, exodus more than 200 routers each)
  from http//kom.tu-darmstad.de/heckmann
• Two border node selection methods
• Random selection
• Max degree selection
• 500 instances of inter-region double path
  computation demands

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Experimental Results (2/4)
2 BN
3 BN
BN random selection
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Experimental Results (3/4)
3 BN
2 BN
BN max degree selection
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Experimental results (4/4)

• JSA (ARO) almost always finds diverse paths (if
  they exist) at the first shot
• Failed in 2-3 cases over thousands of simulation
  runs
• ISPA (RROXRO) was trapped in some topologies at
  the first shot (and should therefore revert to
  crankback)
• Happens approx. in 10 of cases
• When diverse paths are found by all the three
  methods
• No substantial difference in the overall cost
  between JSA (ARO) and optimum (min-hop metric)
  1.5 on average
• Slight worse perf. of ISPA (RROXRO) 6 on
  average
• Detailed summary report available at
  http//www.metanoia-inc.com/Publications/Inter-reg
  ion-Diversepath-Perfcomp.pdf

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Relation with PCE

• With respect to the PCE architecture
  draft-ash-pce-architecture-00.txt
• JSA (ARO) is consistent with Multiple PCE path
  computation with no inter-PCE communications
• Could be used in both region Centralized/Distribu
  ted computation models
• With respect to the PCS/PCE path computation
  scheme draft-vasseur-ccamp-inter-domain-path-comp
  -00.txt , JSA (ARO)
• Achieves same performance as the optimal method
  "almost surely" in practical cases (see from
  simulations, no formal proof yet)
• Involves less information exchange and signaling
  overhead (better scalability)

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Next Actions

• Improve extend performance analysis/simulation
• Open to suggestions from the community
• Carrier/provider input about
• Alternative criteria for selecting the border
  routers?
• Other typical network topologies to test?
• Any input about the scenario(s) for future
  simulations?
• Obtain further WG feedback/inputs on the JSA
  (ARO) scheme
• Progress the document to a WG document