There are two types of BGP neighbors.
1)internal BGP(iBGP)
2)External BGP(EBGP)
A BGP router treats and iBGP and EBGP routers differently.
The rules for iBGP and eBGP routers are different.
If a BGP router is sending an advertisement to a eBGP router then the AS_Path PA is updated and if a BGP router is sending an advertisement to an iBGP router then the AS_Path PA is not updated.
Example.
1)internal BGP(iBGP)
2)External BGP(EBGP)
A BGP router treats and iBGP and EBGP routers differently.
The rules for iBGP and eBGP routers are different.
If a BGP router is sending an advertisement to a eBGP router then the AS_Path PA is updated and if a BGP router is sending an advertisement to an iBGP router then the AS_Path PA is not updated.
Example.
