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9.16 Rate-Limiting Traffic Flow to the Routing Engine<br />

Problem<br />

You need to ensure the availability of the Routing Engine during times of heavy traffic.<br />

Solution<br />

Configure policers to use with the firewall filter that you apply to the Routing<br />

Engine. First, create policers for control and low-priority traffic. The first policer is<br />

for SSH connections to the Routing Engine:<br />

[edit firewall]<br />

aviva@RouterF# set policer ssh if-exceeding bandwidth-limit 1m<br />

aviva@RouterF# set policer ssh if-exceeding burst-size-limit 100k<br />

aviva@RouterF# set policer ssh then discard<br />

Two additional policers limit ICMP and TCP traffic:<br />

[edit firewall]<br />

aviva@RouterF# set policer icmp if-exceeding bandwidth-limit 1m<br />

aviva@RouterF# set policer icmp if-exceeding burst-size-limit 100k<br />

aviva@RouterF# set policer icmp then discard<br />

aviva@RouterF# set policer tcp if-exceeding bandwidth-limit 1m<br />

aviva@RouterF# set policer tcp if-exceeding burst-size-limit 100k<br />

aviva@RouterF# set policer tcp then discard<br />

A final policer affects various background applications, including SNMP, NTP, and<br />

RADIUS:<br />

[edit firewall]<br />

aviva@RouterF# set policer utility if-exceeding bandwidth-limit 3m<br />

aviva@RouterF# set policer utility if-exceeding burst-size-limit 300k<br />

aviva@RouterF# set policer utility then discard<br />

Then, apply the policers in the then clause of the firewall terms that affect TCP, SSH,<br />

ICMP, SNMP, NTP, and RADIUS packets:<br />

[edit firewall filter protect-RE2]<br />

aviva@RouterF# set term tcp from source-prefix-list ssh-prefixes<br />

aviva@RouterF# set term tcp from source-prefix-list bgp-prefixes<br />

aviva@RouterF# set term tcp from protocol tcp<br />

aviva@RouterF# set term tcp from tcp-flags "(syn & !ack) | fin | rst"<br />

aviva@RouterF# set term tcp then policer tcp<br />

aviva@RouterF# set term tcp then accept<br />

aviva@RouterF# set term ssh from prefix-list ssh-prefixes<br />

aviva@RouterF# set term ssh from protocol tcp<br />

aviva@RouterF# set term ssh from destination-port ssh<br />

aviva@RouterF# set term ssh then policer ssh<br />

aviva@RouterF# set term ssh then accept<br />

aviva@RouterF# set term utility from source-prefix-list utility-prefixes<br />

aviva@RouterF# set term utility from protocol udp<br />

aviva@RouterF# set term utility from port [ snmp ntp radius ]<br />

aviva@RouterF# set term utility then policer utility<br />

Rate-Limiting Traffic Flow to the Routing Engine | 327<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.

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