Reference Guide

312 | Border Gateway Protocol IPv4 (BGPv4)
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Usage
Information
BGP uses regular expressions (regex) to filter route information. In particular, the use of
regular expressions to filter routes based on AS-PATHs and communities is quite common. In
a large scale configuration, filtering millions of routes based on regular expressions can be
quite CPU intensive, as a regular expression evaluation involves generation and evaluation of
complex finite state machines.
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
Command
History
Example
FTOS(conf-router_bgp)#no bgp regex-eval-optz-disable
FTOS(conf-router_bgp)#do show ip protocols
Routing Protocol is "ospf 22222"
Router ID is 2.2.2.2
Area Routing for Networks
51 10.10.10.0/00
Routing Protocol is "bgp 1"
Cluster Id is set to 10.10.10.0
Router Id is set to 10.10.10.0
Fast-external-fallover enabled
Regular expression evaluation optimization enabled
Capable of ROUTE_REFRESH
For Address Family IPv4 Unicast
BGP table version is 0, main routing table version 0
Distance: external 20 internal 200 local 200
FTOS(conf-router_bgp)#
bgp router-id
c e s
Assign a user-given ID to a BGP router.
Syntax
bgp router-id ip-address
To delete a user-assigned IP address, enter no bgp router-id.
Parameters
show ip protocols View information on all routing protocols enabled and active on the
E-Series.
Version 8.3.7.0 Introduced on the S4810.
Version 7.8.1.0 Introduced support on S-Series
Version 7.7.1.0 Introduced support on C-Series
Version 7.6.1.0 Introduced
ip-address
Enter an IP address in dotted decimal format to reset only that BGP neighbor.