Solution 1 — Campus iBGP

Two use cases are presented. The first illustrates the extension of BGP into an Enterprise routing environment. The second case shows BGP connectivity in a remote site environment.

Figure 68: Solution 1 — Campus iBGP

Devices

A

WAN Gateway Router

B

Enterprise Core Router

C

Enterprise Core Router (Campus Edge)

D

Campus Core Routing Switch

E

Campus Distribution Routing Switch

F

Edge Switch

In the figure above, multiple campus domains are segmented by using BGP in the Enterprise core. Traditionally, solutions have been used with devices E and F, facing the client or server network edges. With the introduction of BGP functionality, it becomes possible to position solutions at locations B, C, and D.

With proper filtering, a routing switch with 20,000 routes can be used in an iBGP deployment. A device at location C represents the boundary between interior gateway protocol (IGP) domains, and the BGP core. Functionality used on this device includes redistribution with route maps and the establishment of BGP communities. Devices at location B require AS path filtering. All locations within the BGP AS require the remaining “Foundation” features (Route Reflection, Refresh, Multihop, and so forth)

Additional Autonomous Systems may be configured within a network, resembling the Enterprise core module as shown in the diagram. With larger Enterprise customers, it is likely that an AS that is directly adjacent to IGP campus modules will be the location for foundation BGP solutions. See Figure 69: Multiple internal AS deployments with Campus iBGP solution.

Figure 69: Multiple internal AS deployments with Campus iBGP solution

The core routing switch (device C) can establish eBGP peering with the Enterprise Core. It is possible to utilize the foundation Campus iBGP feature to satisfy some of these solutions.

A

Enterprise Core Router

B

Enterprise Core Router (Campus Edge)

C

Campus Core Routing Switch

D

Campus Distribution Routing Switch (or Collapsed Core)

E

Edge Switch

Figure 70: Solution 2 — Remote site iBGP