BGP supports two types
of sessions:
- EBGP session --
Occurs between routers in two different ASs. These routers are
usually adjacent to one another, sharing the same media and a
subnet.
- IBGP session --
Occurs between routers in the same AS, as shown in the Figure,
and is used to coordinate and synchronize routing policy within
the AS. Neighbors may be located anywhere in the AS, even
several hops away from one another.
An IBGP session
occurs between routers in the same AS in an ISP. The IBGP session
coordinates BGP routing policy within an AS.
|