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show dhcpsnooping

17-10 DHCP Snooping and Dynamic ARP Inspection

Usage

ToprotecttheswitchfromDHCPattackswhenDHCPsnoopingisenabled,thesnooping

applicationenforcesarateli mitforDHCPpacketsreceivedonuntrustedinterfaces.DHCP

snoopingmonitorsthereceiverateoneachinterfaceseparately.Ifthereceiverateexceedsthe

configuredlimit,DHCPsnoopingbringsdowntheinterface.You

canre‐enabletheinterfac ewith

thesetportenablecommand.Boththerateandtheburstintervalcanbeconfigured.

Youcandisplaythecurrentlyconfiguredratelimitparameterswiththeshowdhcpsnoopingport

command.

Example

Thisexampleconfiguresratelimitparametersonportge.1.1.

B5(rw)->set dhcpsnooping limit ge.1.1 rate 20 burst interval 2

B5(rw)->show dhcpsnooping port ge.1.1

Interface Trust State Rate Limit Burst Interval

(pps) (seconds)

---------- ------------- ------------- ---------------

ge.1.1 No 20 2

show dhcpsnooping

UsethiscommandtodisplayDHCPsnoopingconfigurationparameters.

Syntax

show dhcpsnooping

Parameters

None.

Defaults

None.

Mode

Switchcommand,read‐write.

Usage

Thiscommanddisplaysthestatus(enabledordisabled)ofDHCPsnoopingglobally,liststhe

VLANsonwhichDHCPsnoopingisenabled,displayswhethersourceMACaddressverification

isenabledordisabled,andforportsthatareenabledforsnooping,displayswhethertheyare

trustedoruntrustedandwhetherloggingofinvalid

packetshasbeenenabled.

Example

Thisexampleshowstheoutputoftheshowdhcpsnoopingcommand.

B5(su)->show dhcpsnooping

DHCP snooping is Enabled

DHCP snooping source MAC verification is enabled

DHCP snooping is enabled on the following VLANs:

Enterasys b5 User Manual

Questions and Answers: