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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 35 Configuring IP Unicast Routing Configuring BGP
BGP Version 4 supports classless interdomain routing (CIDR) so you can 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.
These sections contain configuration information:
• Default BGP Configuration, page 35-45
• Enabling BGP Routing, page 35-48
• Managing Routing Policy Changes, page 35-50
• Configuring BGP Decision Attributes, page 35-51
• Configuring BGP Filtering with Route Maps, page 35-53
• Configuring BGP Filtering by Neighbor, page 35-54
• Configuring Prefix Lists for BGP Filtering, page 35-55
• Configuring BGP Community Filtering, page 35-57
• Configuring BGP Neighbors and Peer Groups, page 35-58
• Configuring Aggregate Addresses, page 35-60
• Configuring Routing Domain Confederations, page 35-61
• Configuring BGP Route Reflectors, page 35-61
• Configuring Route Dampening, page 35-62
• Monitoring and Maintaining BGP, page 35-63
For detailed descriptions of BGP configuration, see the “Configuring BGP” chapter in the “IP Routing
Protocols” part of the Cisco IOS IP Configuration Guide, Release 12.2. For details about specific
commands, see the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release
12.2.For a list of BGP commands that are visible but not supported by the switch, see Appendix C,
“Unsupported Commands in Cisco IOS Release 12.2(46)SE.”
Default BGP Configuration
Table 35-9 shows the basic default BGP configuration. For the defaults for all characteristics, see the
specific commands in the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols,
Release 12.2.
Tab le 35-9 Default BGP Configuration
Feature Default Setting
Aggregate address Disabled: None defined.
AS path access list None defined.
Auto summary Enabled.
Best path • The router considers as-path in choosing a route and does not compare similar
routes from external BGP peers.
• Compare router ID: Disabled.
BGP community list • Number: None defined. When you permit a value for the community number, the
list defaults to an implicit deny for everything else that has not been permitted.
• Format: Cisco default format (32-bit number).