Chapter 8: Basic BGP

Commands:

8.4.2 and 8.4.3 Configuring BGP for a single connection to an ISP

Router(config)# router bgp autonomous system number
Router(config-router)#neighbor ip address of neighbor remote-as AS#
Router(config)#network x.x.x.x
Router#clear ip bgp *

8.4.4 Comparing EBGP and IBGP connections

Router#show ip bgp neighbors

8.5.1 Show commands

Router#show ip bgp
Router#show ip bgp paths
Router#show ip bgp summary
Router#show ip bgp neighbors

8.6.1 Configuration example: Building Peer Sessions

Router(config)#ip subnet-zero
Router(config)#interface type slot/port
Router(config-if)#ip address ip-address mask [secondary]

Router(config)#router process [process-id]

Router(config-router)#network
Router(config-router)#inverse mask
Router(config-router)#area area-number

Router(config-router)#neighbor
Router(config-router)#no synchronization
Router(config-router)#no auto-summary

ip classless
update-source interface
remote-as
ebgp-multihop 2

8.6.3 How synchronization works

router(config-router)#no synchronization

8.7.4 BGP Route Maps

Router(config)#route-map map-tag [[permit | deny] | [sequence-number]]
Router(config)# route-map MYMAP permit 10
! First set of conditions goes here.
Router(config)#route-map MYMAP permit 20
! Second set of conditions goes here

Router(config)# access-list access-list-number {deny | permit} source [source-wildcard]

 

8.7.8 Next-hop Behavior over NBMA

Router(config-router)#neighbor x.x.x.x next-hop-self

8.8.2 Configuration example: Removing Private AS Numbers

Router(config-router)#neighbor x.x.x.x remove-private-AS

8.8.4 Configuration example: AS-Path Manipulation

Router(config-router)#neighbor x.x.x.x route-map name [in | out]
Router(config)#route-map name {permit | deny} instance number
Router(config-route-map)#set as-path prepend AS# AS# AS#

8.8.6 Configuration example: Setting the Local Preferenece Attribute

Router(config-router)#bgp default local-preference pref-number
Router(config-route-map)#set local-preference pref-number

8.8.7 The MED Attirbute

Router(config-router)# bgp always-compare-med

8.8.8 Configuration example: MED

Router(config-router)# bgp always-compare-med
Router(config-route-map)#set metric value