Dell Force10 S4820T FTOS Command Reference Guide - Page 323

Command Modes Usage Information Related Commands Command History ROUTER BGP This command is a knob to disable BGP next-hop resolution via BGP learned routes. During the next-hop resolution, only the first route that the next-hop resolves through is verified for the route's protocol source and is checked if the route is learned from BGP or not. The clear ip bgp command is required for this command to take effect and to keep the BGP database consistent. Execute the clear ip bgp command right after executing this command. clear ip bgp Description. Version 8.3.19.0 Version 8.3.7.0 Version 7.8.1.0 Version 7.7.1.0 Version 7.2.1.0 Introduced on the S4820T. Introduced on the S4810. Introduced support on S-Series Introduced support on C-Series Introduced bgp regex-eval-optz-disable c e s Disables the Regex Performance engine that optimizes complex regular expression with BGP. Syntax Defaults Command Modes Usage Information bgp regex-eval-optz-disable To re-enable optimization engine, use the no bgp regex-eval-optz-disable command. Enabled by default ROUTER BGP (conf-router_bgp) 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. Border Gateway Protocol IPv4 (BGPv4) | 323