OSPF Outofband LSDB Resynchronization using Zebra in Linux

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OSPF Out-of-band LSDB Resynchronization using
Zebra in Linux

• EECS845 Implementation of High Performance
  Networks
• Instructor Dr Joseph Evans
• by
• KP Muthuvelan ( 703847 )
• Roopesh Rajamani ( 698645 )

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• Introduction
• LSDB should be synchronized for neighbors to be
  Adjacent.
• LSDB synchronization done in 2 ways
• Initial synchronization
• Asynchronous Flooding
• Motivation
• In OSPFv2, only topology changes lead to LSDB
  resynchronization.
• Forcing LSDB resynchronization lead to removal of
  Adjacency in Router-LSAs.

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Solution

• OSPF DBD packets changed to include a new
  R-bit indicating OOB LSDB resynchronization.
• DBD packet sent with R-bit set during OOB
  resynchronization.
• Fields added to the neighbor data structure to
  indicate OOB resync activity.

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Implementation Details

• Done in zebra version 0.91a.
• Added a field to indicate OOBResync in OSPF
  neighbor structure.
• Changes to set/reset the R-bit in DBD packets.
• Changes in the NSM based on the type of DBD
  packet.
• If LSDB resynchronization not done within a fixed
  period then normal synchronization started by
  putting the NSM to ExStart state.

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Future Work

• The capability of routers to perform OOB
  resynchronization has to be advertised to each
  other.
• Since not enough OSPF options field left, we can
  use LLS. An EO-TLV can be used to advertise the
  capability.

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References

• J. Moy. OSPF version 2. Technical Report RFC
  2328, Internet Engineering Task Force, 1998.
• Zinin, Roy, Nguyen, "OSPF Out-of-band LSDB
  resynchronization", draft-ietf-ospf-oob-resync-01.
  txt, Work in progress.
• Zinin, Friedman, Roy, Nguyen, Yeung, "OSPF
  Link-local Signaling", draft-ietf-ospf-lls-00.txt,
  Work in progress.