| Exam 642-885 | Question id=3325 | BGP Routing Features in a Service Provider IP NGN Environment |
Which type of BGP session behaves like an EBGP session during session establishment but behaves like an IBGP session when propagating routing updates where the local preference, multi-exit discriminator, and next-hop attributes are not changed?
| A. |
BGP sessions between a route reflector and its clients | |
| B. |
BGP sessions between a route reflector and its non-client IBGP peers | |
| C. |
BGP sessions between a route reflector and another route reflector | |
| D. |
Intra-confederation IBGP sessions | |
| E. |
Intra-confederation EBGP sessions |
BGP Routing Domain Confederation
One way to reduce the iBGP mesh is to divide an autonomous system into multiple subautonomous systems and group them into a single confederation. To the outside world, the confederation looks like a single autonomous system. Each autonomous system is fully meshed within itself and has a few connections to other autonomous systems in the same confederation. Although the peers in different autonomous systems have eBGP sessions, they exchange routing information as if they were iBGP peers. Specifically, the next hop, MED, and local preference information is preserved. This feature allows you to retain a single IGP for all of the autonomous systems.