Dell S4810 Reference Manual page 396

Version 9.0.2.0
Version
8.3.19.0
Version 8.3.11.1
Version 8.3.7.0
Version 7.8.1.0
Version 7.7.1.0
Version 7.6.1.0
Usage
BGP uses regular expressions (regex) to filter route information. In particular, the
Information
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)#
Related show ip protocols
Commands on the E-Series.
396
Introduced on the S6000.
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
— views information on all routing protocols enabled and active
Routing for Networks
10.10.10.0/00
Border Gateway Protocol