MANET Extension of OSPF Using CDS Flooding

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MANET Extension of OSPF Using CDS Flooding
IETF Meeting - OSPF WG
draft-ogier-manet-ospf-extension-10.txt

• Authors Richard Ogier and Phil Spagnolo
• December 3, 2007

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Changes for OSPF-MDR version 10

• Several changes to improve readability.
• A more unified treatment of partial-topology and
  full-topology LSAs that applies to all choices of
  the parameters LSAFullness and AdjConnectivity.
• The LSA construction was modified in version 9 to
  achieve the following properties
• Each router selects a set of neighbors to include
  in its router-LSA and indicates this set in Hello
  packets.
• The LSA construction ensures that if Router A
  advertises Router B in its LSA, then Router B
  advertises Router A (symmetry).
• If LSAFullness 1, then neighbor link metrics
  are advertised in the Metric TLV appended to
  Hellos, and shortest-path routing is ensured.

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Changes for OSPF-MDR version 10 (cont.)

• The detailed algorithm for Backup MDR selection
  was simplified in version 9, and an even simpler
  option is specified in version 10, which is
  simply the first step of the full algorithm.
• Added the optional Phase 5 to the MDR selection
  algorithm, which allows an MDR to declare itself
  non-flooding if it can determine that it need
  not flood LSAs because neighboring MDRs are
  adequate. This helps to reduce flooding
  overhead.
• Removed the section titled "Optional Treatment of
  Broadcast Network as MANET". This section was
  made obsolete by extending the definition of a
  neighbor that is "covered" by an LSA, to allow
  the LSA to be sent by a neighbor on a broadcast
  (non-MANET) interface.

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Changes for OSPF-MDR version 10 (cont.)

• Packet format changes
• Instead of appending to each Hello a separate LLS
  TLV for each of five possible neighbor lists,
  neighbor IDs are listed in the body of the Hello,
  and a single Hello TLV indicates the number of
  neighbors in each neighbor list. (Saves several
  bytes and reduces number of required TLV types.)
• The Metric TLV has been modified to allow the
  option of giving the metrics for all neighbors
  listed in the body of the Hello (in the same
  order) and omitting the neighbor RIDs in the TLV
  (to avoid listing each neighbor RID twice.)

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OSPF-MDR Simulation Update

• Ogier updated Boeings GTNetS code for OSPF-MDR
  to incorporate the updated min-cost LSA algorithm
  specified in draft version 9, and ran simulations
  to compare to INRIAs MPR-OSPF. Results were
  posted on the ospf-manet list on 3/5/2007.
• OSPF-MDR achieved significantly lower overhead
  and significantly higher delivery ratio,
  especially in large networks(up to 100 nodes).
• For 100 nodes, MPR-OSPF resulted in 10 times as
  many adjacency formations per second as OSPF-MDR.
• Plans include
• Update the GTNetS code to comply with draft
  version 10, and continue to conduct simulations
  to evaluate performance.
• Update the Quagga-based implementation and
  contribute to the Quagga project.