Border Gateway Protocol And Classless Interdomain Routing; Configuring Bgp; Verifying The Bgp Configuration - Cisco ONS 15454 Software Feature And Configuration Manual

Configuring IP Routing
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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
OSPF, EIGRP, and RIP.

Configuring BGP

To configure BGP routing, perform the following steps, beginning in global configuration mode:
Command
Step 1
Router(config)# ip routing
Step 2
Router(config)# router bgp autonomous-system
Step 3
Router(config-router)# network network-number
[mask network-mask ] [route-map route-map-name ]
Step 4
Router(config-router)# end
The following example shows how to configure BGP routing:
Router(config)# ip routing
Router(config)# router bgp 30
Router(config-router)# network 192.168.1.1
Router(config-router)# neighbor 192.168.2.1
Router(config-router)# end
For more information about configuring BGP routing, refer to the "Configuring BGP" chapter in the
Cisco IOS IP and IP Routing Configuration Guide.

Verifying the BGP Configuration

Table 10-6 on page 10-29
Cisco ONS 15454 SONET/SDH ML-Series Multilayer Ethernet Card Software Feature and Configuration Guide, R4.0
10-28
lists some common EXEC commands used to view the BGP configuration.
Chapter 10 Configuring Networking Protocols
Purpose
Enables IP routing (default.)
Defines BGP as the routing protocol and starts
the BGP routing process.
Flags a network as local to this autonomous
system and enters it in the BGP table.
Returns to privileged EXEC mode.
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