Chapter 38 Configuring IP Unicast Routing

Configuring BGP

 

Command

Purpose

Step 5

 

 

neighbor {ip-address peer-group-name}

Add an entry to the BGP neighbor table specifying that the

 

remote-as number

neighbor identified by the IP address belongs to the specified

 

 

AS.

 

 

For EBGP, neighbors are usually directly connected, and the IP

 

 

address is the address of the interface at the other end of the

 

 

connection.

 

 

For IBGP, the IP address can be the address of any of the router

 

 

interfaces.

Step 6

 

 

neighbor {ip-address peer-group-name}

(Optional) Remove private AS numbers from the AS-path in

 

remove-private-as

outbound routing updates.

Step 7

 

 

no synchronization

(Optional) Disable synchronization between BGP and an IGP.

Step 8

 

 

no auto-summary

(Optional) Disable automatic network summarization. By

 

 

default, when a subnet is redistributed from an IGP into BGP,

 

 

only the network route is inserted into the BGP table.

Step 9

 

 

bgp fast-external-fallover

(Optional) Automatically reset a BGP session when a link

 

 

between external neighbors goes down. By default, the session

 

 

is not immediately reset.

Step 10

 

 

bgp graceful-restart

(Optional) Enable NSF awareness on switch. By default, NSF

 

 

awareness is disabled.

Step 11

 

 

end

Return to privileged EXEC mode.

Step 12

 

 

show ip bgp network network-number

Verify the configuration.

 

or

 

 

show ip bgp neighbor

Verify that NSF awareness (Graceful Restart) is enabled on the

 

 

 

 

neighbor.

 

 

If NSF awareness is enabled on the switch and the neighbor,

 

 

this message appears:

 

 

Graceful Restart Capability: advertised and received

 

 

If NSF awareness is enabled on the switch, but not on the

 

 

neighbor, this message appears:

 

 

Graceful Restart Capability: advertised

Step 13

 

 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

 

 

 

Use the no router bgp autonomous-systemglobal configuration command to remove a BGP AS. Use the no network network-numberrouter configuration command to remove the network from the BGP table. Use the no neighbor {ip-address peer-group-name} remote-asnumber router configuration command to remove a neighbor. Use the no neighbor {ip-address peer-group-name} remove-private-asrouter configuration command to include private AS numbers in updates to a neighbor. Use the synchronization router configuration command to re-enable synchronization.

These examples show how to configure BGP on the routers in Figure 38-5.

Router A:

Switch(config)# router bgp 100

Switch(config-router)#neighbor 129.213.1.1 remote-as 200

 

 

Catalyst 3750-E and 3560-E Switch Software Configuration Guide

 

 

 

 

 

 

OL-9775-02

 

 

38-49

 

 

 

 

 

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Cisco Systems 3750E manual 38-49