"?", "E" and "I" in BGP AS-path

m4rtinm4rtin Member Posts: 170
I have seen following AS-path in routing tables:
AS path: I

..which should mean that network is connected to and learned from a router which is an iBGP router? This AS-path:
AS path: 3356 24931 I

..should mean that prefix is reachable through AS3356 and then through AS24931. Does the prefix belong to AS24931 and what does the "I" stand for in this case?

What does a question mark mean in this case?
AS path: 12573 6617 12431 42722 ?

Last but not least, in which case ASN is:
AS path: E

AS path: 64512 E


  • Options
    mayhem87mayhem87 Member Posts: 73 ■■□□□□□□□□
    I basically means it was in the routing table of a router through some type of IGP and then put into BGP. In cisco its from the network command not sure if this still applies to juniper as they dont have examples.

    E is from EGP which is no longer used according to the books

    ? is if the route was redistributed into the protocol. IE take a OSPF route and then redistribute it into bgp rather then listing it in the network statement.

    Again this is what I know they mean through cisco and I am assuming they are probably the same in Juniper.

    The last AS is the AS it belongs to and who originated the route.
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