Dell PowerEdge FN I/O Module Command Line Reference Guide 9.10(0.0)

To re-enable optimization engine, use the no bgp regex-eval-optz-disable command.

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.

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)#