Users Guide

Command
History
This guide is platform-specific. For command information about other platforms, refer to the relevant Dell
Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version 8.3.19.0 Introduced on the S4820T.
Version 8.4.2.1 Introduced on the C-Series and S4810.
Version 8.2.1.0 Introduced on the E-Series ExaScale.
Version 7.4.1.0 Introduced on the E-Series TeraScale.
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.
For this command to take effect and to keep the BGP database consistent, you need the clear ip
bgp command. Execute the clear ip bgp command right after executing this command.
Related
Commands
capture bgp-pdu max-buffer-size
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
This guide is platform-specific. For command information about other platforms, refer to the relevant Dell
Networking OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version 8.3.19.0 Introduced on the S4820T.
Version 8.4.2.1 Introduced on the C-Series and S4810.
Version 8.2.1.0 Introduced on the E-Series ExaScale.
Version 7.4.1.0 Introduced on the E-Series TeraScale.
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 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.
Related
Commands
show ip protocols – views information on all routing protocols enabled and active.
856 IPv6 Border Gateway Protocol (IPv6 BGP)