I have a question about the AS path, see the below example where I show the route

enter image description here

This shows several BGP routes.

See the fist route item.

The AS path is 4809 4134 I, I want to know if the is in AS 4134? because I stands for IGP.

If it's in AS 4134, then how do I explain the second route item which is currently AS 174?

We know that if a route gets out of an AS, it will append the AS number, so we should know the last AS number is the ISP AS number.

  • Yes, the network is being advertised by both ChinaNet and Cogent. The reasons may have more to do with politics than anything technical.
    – Ron Trunk
    Commented Apr 2, 2019 at 12:10

1 Answer 1


You are right. The last AS in the 'AS' string belongs to that AS who actually advertises that route or who actually originate that route. It is the AS who owns that route. No matter the route is owned by that ISP or by his customer , it has been originated by that AS.

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