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BGP policies, containing regular expressions to match as-path and communities, tend to use a lot of
CPU processing time, which in turn affects the BGP routing convergence. Additionally, the show bgp
commands, which are filtered through regular expressions, use up CPU cycles particularly with large
databases. The Regex Engine Performance Enhancement feature optimizes the CPU usage by caching
and reusing regular expression evaluation results. This caching and reuse may be at the expensive of RP1
processor memory.
Related
Commands
show ip protocols — views information on all routing protocols enabled and active.
bgp router-id
Assign a user-given ID to a BGP router.
Syntax
bgp router-id ip-address
To delete a user-assigned IP address, use the no bgp router-id command.
Parameters
ip-address Enter an IP address in dotted decimal format to reset only that BGP neighbor.
Defaults The router ID is the highest IP address of the Loopback interface or, if no Loopback interfaces are
configured, the highest IP address of a physical interface on the router.
Command Modes ROUTER BGP
Supported Modes Full–Switch
Command
History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
Usage
Information
Peering sessions are reset when you change the router ID of a BGP router.
bgp soft-reconfig-backup
Use this command only when route-refresh is not negotiated between peers to avoid having a peer re-send BGP updates.
Syntax
bgp soft-reconfig-backup
To return to the default setting, use the no bgp soft-reconfig-backup command.
Defaults Off
Command Modes ROUTER BGPV6 ADDRESS FAMILY (conf-router_bgpv6_af)
Supported Modes Full–Switch
Command
History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
Usage
Information
When you enable soft-reconfiguration for a neighbor and you execute the clear ip bgp soft in
command, the update database stored in the router replays and updates are reevaluated. With this
command, the replay and update process is triggered only if route-refresh request is not negotiated with
the peer. If the request is negotiated (after execution of clear ip bgp soft in), BGP sends a
route-refresh request to the neighbor and receives all of the peer’s updates.
Related
Commands
clear ip bgp ipv6 unicast soft — activates inbound policies for IPv6 routes without resetting the BGP TCP
session.
IPv6 Border Gateway Protocol (IPv6 BGP) 613