Command
History
Version 9.2(0.0)
Introduced on the MXL 10/40GbE Switch IO Module.
Usage
Information
This command is a
knob
to disable BGP next-hop resolution using 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.
Related
Commands
clear ip bgp
— clears the ip bgp.
bgp regex-eval-optz-disable
Disables the Regex Performance engine that optimizes complex regular expression with BGP.
Syntax
bgp regex-eval-optz-disable
To re-enable optimization engine, use the
no bgp regex-eval-optz-disable
command.
Defaults
Enabled
Command
Modes
ROUTER BGP (conf-router_bgp)
Command
History
Version 9.2(0.0)
Introduced on the MXL 10/40GbE Switch IO Module.
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"
Router ID is 2.2.2.2
Border Gateway Protocol IPv4 (BGPv4)
325
