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Syntax Description:

• ip-address— Neighbor’s IP address.

• peer-group-name— Name of the peer group. See section 8-19.

Purpose: If you have a policy configured with a BGP neighbor, such as a route map or distribute list, and you change the policy, the BGP session needs to be cleared in order for the new policy to take effect. When a BGP session is cleared, the cache is invalidated. This has a momentary impact on your routing. The soft-reconfiguration option allows you to change policies without clearing the BGP session. The two forms of soft reconfiguration are inbound and outbound. When you use inbound, soft reconfiguration updates from a neighbor are stored in memory, regardless of the inbound policy. Be aware that using inbound soft reconfiguration uses more memory than not using inbound soft reconfiguration. Outbound soft reconfiguration does not require additional memory and is always enabled.

Cisco IOS Software Release: 11.2

Configuration Example: Setting Inbound Soft Reconfiguration with a Specific Neighbor

To configure inbound soft reconfiguration with a specific neighbor, use the following configuration as a guide:

router bgp 2

 neighbor 10.1.1.2 remote-as 1

 neighbor 10.1.1.2 soft-reconfiguration inbound

Verification

Use the show ip bgp neighbors command to verify that soft reconfiguration has been enabled:

router#

BGP neighbor is 10.1.1.2,  remote AS 1, external link

 Index 1, Offset 0, Mask 0x2

  Inbound soft reconfiguration allowed

  BGP version 4, remote router ID 172.16.1.1

  BGP state = Established, table version = 6, up for 00:00:33

  Last read 00:00:33, hold time is 180, keepalive interval is 60 seconds

  Minimum time between advertisement runs is 30 seconds

  Received 52 messages, 0 notifications, 0 in queue

  Sent 58 messages, 0 notifications, 0 in queue

  Connections established 5; dropped 4

Connection state is ESTAB, I/O status: 1, unread input bytes: 0

Local host: 10.1.1.1, Local port: 11456

Foreign host: 10.1.1.2, Foreign port: 179

Troubleshooting

1. Verify that the BGP neighbors are in the Established state using the show ip bgp neighbors command.

   If the neighbor relationship is not in the Established state, see section 8-23.

2. Verify that soft reconfiguration inbound has been enabled by using show ip bgp neighbors.

3. If the session is established and soft reconfiguration has not been enabled, check the neighbor’s IP address in the neighbor ip-address soft-reconfiguration inbound command.

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