BGP AS-Override
This feature rewrites a customer AS_PATH attribute.
This command is run on the ISP router.
Example
- eBGP
- Two BGP speakers with the same AS
┌─ eBGP ─┐ ┌─ eBGP ─┐
▼ ▼ ▼ ▼
┌────────┐ ┌────────┐ ┌────────┐
│ R1 │ │ ISP │ │ R2 │
│AS 64496├────────┤AS 64511├────────┤AS 64496│
└────────┘ └────────┘ └────────┘
10.64.1.0/24 10.64.2.0/24
R1 and R2 would like to exchange reachability information with each other, but the ISP router is between them.
When the ISP router gets the updates, it will re-write 64496, as 64511.