bgp regexp deterministic

Short notes from cisco

The default Cisco IOS regular expression engine uses a recursive algorithm.
This engine is effective but uses more system resources as the complexity of regular expressions increase.
In some cases, CPU watchdog timeouts and stack overflow traces have occurred because of the length of time that the default engine requires to process very complex regular expressions.
The Regex Engine Performance Enhancement feature introduces a deterministic processing time regular expression engine in Cisco IOS software.
if you need to evaluate complex regular expressions or if you have observed problems related to evaluating regular expressions, recommanded use new regular expression engine.

Steps to do,
- enable BGP
- bgp regexp deterministic

Router> enable
Router# configure terminal
Router(config)# router bgp 1
Router(config-router)#bgp regexp deterministic

more
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gt_rexpe.html