11-27
Ethernet Card Software Feature and Configuration Guide, R7.2
January 2009
Chapter 11 Configuring Networking Protocols
Border Gateway Protocol and Classless Interdomain Routing
P 192.168.1.0/24, 1 successors, FD is 30720
via 192.168.2.1 (30720/28160), POS0
P 192.168.2.0/24, 1 successors, FD is 10752
via Connected, POS0
P 192.168.3.0/24, 1 successors, FD is 28160
via Connected, FastEthernet0
Example 11-13 show ip eigrp traffic Privileged EXEC Co mmand Output
Router# show ip eigrp traffic
IP-EIGRP Traffic Statistics for process 1
Hellos sent/received: 273/136
Updates sent/received: 5/2
Queries sent/received: 0/0
Replies sent/received: 0/0
Acks sent/received: 1/2
Input queue high water mark 1, 0 drops
SIA-Queries sent/received: 0/0
SIA-Replies sent/received: 0/0
Border Gateway Protocol and Classless Interdomain Routing
Border Gateway Protocol (BGP) is an Exterior Gateway Protocol (EGP) that allows you to set up an
interdomain routing system to automatically guarantee the loop-free exchange of routing information
between autonomous systems. In BGP, each route consists of a network number, a list of autonomous
systems that information has passed through (called the autonomous system path), and a list of other path
attributes.
Layer 3 switching supports BGP version 4, including CIDR. CIDR lets you reduce the size of your
routing tables by creating aggregate routes resulting in supernets. CIDR eliminates the concept of
network classes within BGP and supports the advertising of IP prefixes. CIDR routes can be carried by
OSP F, E IGR P, a nd R IP.

Configuring BGP

To configure BGP routing, perform the following steps, beginning in global configuration mode:
Example 11-14 shows and example of configuring BGP routing.
Example 11-14Configuring BGP Routing
Router(config)# ip routing
Command Purpose
Step 1 Router(config)# ip routing Enables IP routing (default).
Step 2 Router(config)# router bgp
autonomous-system
Defines BGP as the routing protocol and starts
the BGP routing process.
Step 3 Router(config-router)# network
network-number
[mask
network-mask
] [route-map
route-map-name
]
Flags a network as local to this autonomous
system and enters it in the BGP table.
Step 4 Router(config-router)# end Returns to privileged EXEC mode.