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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 — clear 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
This guide is platform-specific. For command information about other platforms, see the relevant Dell
EMC Networking OS Command Line Reference Guide.
Version Description
9.10(0.1) Introduced on the S6010-ON and S4048T-ON.
9.10(0.0) Introduced on the S3148.
9.10(0.0) Introduced on the S6100-ON.
9.8(2.0) Introduced on the S3100 series.
9.8(1.0) Introduced on the Z9100–ON.
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
9.7(0.0) Introduced on the S6000–ON.
9.2(1.0) Introduced on the Z9500.
9.0.2.0 Introduced on the S6000.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.7.0 Introduced on the S4810.
7.8.1.0 Introduced on the S-Series.
7.7.1.0 Introduced on the C-Series.
7.6.1.0 Introduced
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.
358 Border Gateway Protocol