Dell C1048P Port Extender Networking Command-Line Reference Guide for the C900 - Page 409

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 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 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 Related Commands Dell(conf-router_bgp)# no bgp regex-eval-optz-disable Dell(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 Dell(conf-router_bgp)# show ip protocols - views information on all routing protocols enabled and active on the E-Series. Border Gateway Protocol 409