Dell C9000 Series Reference Manual page 437

Command History
This guide is platform-specific. For command information about other platforms, refer
to the relevant Dell Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version
9.9(0.0)
9.2(1.0)
8.3.19.0
8.3.11.1
8.3.7.0
7.8.1.0
7.7.1.0
7.6.1.0
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 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 much 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.
Examples
Dell(conf-router_bgp)# no bgp regex-eval-optz-disable
Dell(conf-router_bgp)# do show ip protocols
Routing Protocol is "ospf 22222"
Routing Protocol is "bgp 1"
Regular expression evaluation optimization enabled
Dell(conf-router_bgp)#
Description
Introduced on the C9010.
Introduced on the Z9500.
Introduced on the S4820T.
Introduced on the Z9000.
Introduced on the S4810.
Introduced on the S-Series.
Introduced on the C-Series.
Introduced
Router ID is 2.2.2.2
Area
51
Cluster Id is set to 10.10.10.0
Router Id is set to 10.10.10.0
Fast-external-fallover 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
Routing for Networks
10.10.10.0/00
Border Gateway Protocol 437