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Saturday, January 29, 2011

Note from IPExpect (Redistribution)

Note about Problem in Redistribution

  • When redistribution OSPF in to BGP, by default, BGP only accepts internal routes not external type 1 or type 3
  • Beware of the metric used by RIP
  • Watch for the administrative distance prolems especially since IGRP has a lower distance than OSPF
  • Redistributing in to RIP require a metric or default-metric or it may get set to 16
  • Always filter routes when doing redistribution

When Redistributing from on protocol to another 
  • Each protocol has its own rules
  • The path redistributed must be RIB best path
  • The path redistributed must be in the routing table
  • Connected routes always win.
  • Results may or may not be expected

Metric
  • You must set metric in RIP
  • You must set metric in EIGRP except for Connected, Static to interface
  • OSPF metric is 20 (for BGP is 1 )
  • BGP has no metric, but origin is incomplete.

Redistribution Oddities
  • Route map configuration allows.
  • match ip address 
  • match ip next-hop
  • match interface ( of IP next hop)
  • and others
  • Conditional redistribution can occur.
  • Redistribute from RIP to OSPF only if the next hop is 'x' (where /x/ may be the less-preffered RIP path)


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