CLI Guide

Usage Information
This command is a knob to disable BGP next-hop resolution using BGP learned routes. During the next-hop
resolution, only the rst route that the next-hop resolves through is veried 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 eect 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)
Supported Modes Full–Switch
Command History
Version Description
9.9(0.0) Introduced on the FN IOM.
9.2(0.0) Introduced on the MXL 10/40GbE Switch IO Module.
Usage Information
BGP uses regular expressions (regex) to lter route information. In particular, the use of regular expressions to lter
routes based on AS-PATHs and communities is common. In a large-scale conguration, ltering millions of routes
based on regular expressions can be quite CPU intensive, as a regular expression evaluation involves generation
and evaluation of complex nite state machines.
BGP policies, containing regular expressions to match as-path and communities, tend to use much CPU processing
time, which in turn aects the BGP routing convergence. Additionally, the show bgp commands, which are
ltered 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
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
Border Gateway Protocol IPv4 (BGPv4) 299