The Origin attribute identifies the originating source of the route –

  • i (IGP) – Originated from an interior gateway protocol (such as EIGRP,RIP etc).This indicates the route was injected into BGP via the network command under the BGP process.
  • e (EGP) – Originated from an external gateway protocol.
  • ? (incomplete) – Unknown origin. This usually indicates the route was redistributed into BGP (from either connected, static, or IGP routes). An origin code of “?” is the least preferred.
  • From amongst the above 3 origin codes, “i”is the most preferred while “?” is the least preferred.

Below is the scenario where 3 Routers R1, R2 and R3 are connected in serial. With each in different Autonomous system no i.e. 1, 2 and 3 respectively.

In the BGP routing table of R2 , the origin code is listed at the end of each line in the table –


The “i” at the end of the first routing entry indicates the network was originated via an IGP, via the BGP network command. The network was redistributed into BGP in AS 3, since it shows “?” at the end of that routing entry

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