BGP: ORIGIN Path Attribute

Three Origin Path Attribute values exist:

  • IGP
  • EGP
  • incomplete

IGP – denotes network, aggregate address, and neighbor default originate commands

EGP – denotes the old Exterior Gateway Protocol….NOT eBGP

Incomplete – denotes redistributed routes, aggregate address and default information originate

The ORIGIN Attribute provides a general descriptor as to how a NLRI was injected into a routers BGP table.

ORIGIN codes used with the aggregate-address command are:

  • If the as-set option is NOT used, the aggergate routes ORIGIN code is IGP (i)
  • If the as-set option IS used, and all component networks use ORIGIN code i, the aggregates ORIGIN code will match
  • If the as-set option IS used, and any of the ORIGIN codes on the component network routes include an incomplete (?)……. incomplete (?) is used
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