Cisco Cisco IOS Software Release 12.0(22)S

A soft reset, which is performed on a per-neighbor basis, does not clear the BGP session and facilitates 
the application of new policies. There are two methods of performing a soft reset:

A dynamic inbound soft reset is used to generate inbound updates from a neighbor. 

An outbound soft reset is used to send a new set of updates to a neighbor. 

Before the BGP Soft Reset Enhancement feature, a soft reset for inbound routing table updates was 
performed by entering the neighbor soft-reconfiguration router configuration command. This 
command was used to configure the local BGP router to store all received (inbound) routing policy 
updates. However, this method uses too much memory because inbound updates are not modified and is 
not recommended. 

Outbound resets have never required preconfiguration or storing of routing table updates and remain 
unchanged by the BGP Soft Reset Enhancement. The procedure for an outbound reset is described in the 
section “Reset BGP Connections” in the Cisco IOS Release 12.0 Network Protocols Configuration Guide, 
Part 1.

When the routing policy of a BGP neighbor changes, the session must be reset (cleared) for the changes 
to take effect. Because resetting a BGP session can be disruptive to networks, a soft reset method is 
recommended for reconfiguring the routing table. 

In order to reconfigure the inbound routing table before the introduction of this feature, both the local 
BGP router and the BGP peer first needed to be configured to store incoming routing policy updates 
using the neighbor soft-reconfiguration command. Additional resources, particularly memory, were 
required to store the inbound routing table updates. The clear ip bgp command could then initiate the 
soft reset, which generated a new set of inbound routing table updates using the stored information. 

This feature provides an additional method for soft reset that allows the dynamic exchange of route 
refresh requests and routing information between BGP routers and the subsequent re-advertisement of 
the respective outbound routing table. Soft reset using the route refresh capability does not require 
preconfiguration and consumes no additional memory resources. 

To use this new method, both BGP peers must support the soft route refresh capability, which is 
advertised in the OPEN message. Any router that is running BGP with this software release 
automatically supports the route refresh capability. Routers that are running previous Cisco IOS software 
releases do not support the route refresh capability and must use the older soft reset method. 

If the soft reset fails, you can still clear the BGP session, but it will have a negative impact upon network 
operations and should only be used as a last resort.

This feature provides a way to initiate nondisruptive routing policy changes by allowing the dynamic 
exchange of route refresh requests between BGP routers and the subsequent re-advertisement of the 
respective outbound routing tables.