Can one IP address correspond to multiple ASNs

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Can one IP address correspond to multiple ASNs? If so, what were the circumstances? Is it related to anycast ip address? thanks!

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crafter On

Yes, it's called a Multi Origin AS (MOAS). Here is a brief explanation to a stack readers:

To exchange reachability information about IP addresses, different Autonomous Systems (ASes) in the Internet use BGP. In BGP, each IP address prefix (i.e., collection of IP addresses) is usually originated by a single AS. There are, however, also cases where multiple ASes originate the same prefix, this prefix is in turn called a Multi Origin AS (MOAS) prefix. Network operators use MOAS prefixes to e.g., provide resilience, load balancing, and multi-homing.

Further details: https://arxiv.org/pdf/2307.08490.pdf
Proof of concept:
https://bgp.he.net/report/multi-origin-routes#_ipv4multioriginroutes
https://stat.ripe.net/ui2013/193.104.254.82#tabId=routing

Must mention though that it's not recommended to do, but it terms of the question, it's possible and present all over the internet.

0
Andrew On

No, each IP address is associated with a unique origin ASN. You could however have a more specific prefix from a different ASN. For example, 189.50.192.0/20 => ASN1 and 189.50.192.0/22 => ASN2.

All anycast locations would need to be originated from the same ASN.