Information Technology Reference
In-Depth Information
required in redundant regional environments. A default route is injected into the regional
IGP process on each of the regional border routers.
Figure 5-10
Internal/External BGP Architecture
EIGRP 102
BGP 65102
R7
R5
R1
R6
R4
EIGRP 103
BGP 65103
EIGRP 100
BGP 65100
R8
EIGRP 101
BGP 65101
R3
R10
R9
R2
R11
R12
EIGRP 104
BGP 65104
The regional border router is a new concept introduced in this architecture. The DMZ
between the core and a region is the connection between the regional border router and the
core router. The regional border router exists entirely in the region and connects to the
network core via eBGP. This separates regional routing from core routing. In the previous
architectures, the regional border router functionality was shared with the core router
functions on the same device.
The core IGP is used to provide next-hop resolution and reachability for the iBGP peering
sessions between core routers. The core IGP contains only the core routers, core links, and
loopback interfaces on the core routers. The core IGP process does not participate in any
redistribution between protocols.
