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Enterasys Networks XSR CLI Router User Manual

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BGP Set Commands

6-116 Configuring the Border Gateway Protocol

Syntax of the “no” Form

Thenoformofthiscommandremovesthesetcommunityvalue:

no set community

Mode

Route‐mapconfiguration:XSR(config-route-map)#

Example

Thefollowingexampleconfiguresthesetcommunityvalueinthecontextofconfiguringroutemap

1andtheneighborsendcommunityvalue:

XSR(config)#ip access-list 37 permit 10.0.0.0 255.0.0.0

XSR(config)#route-map 1 permit 1

XSR(config-route-map)#match ip address 37

XSR(config-route-map)#set community 500:10

XSR(config-route-map)#exit

XSR(config)#route-map 1 permit 2

XSR(config-route-map)#set community none

XSR(config-route-map)#exit

XSR(config)#router bgp 100

XSR(config-router)#neighbor 192.168.1.1 remote-as 101

XSR(config-router)#neighbor 192.168.1.1 send-community

XSR(config-router)#neighbor 192.168.1.1 route-map 1 out

Routemap1isappliedtotheoutgoingBGPupdatesbetweenthisrouteranditspeeringneighbor

identifiedbyIPaddress192.168.1.1inAS101.Thefirstinstanceofroutemap1matchesthe

destinationsintheBGPupdatesagainstthecriteriaspecifiedinACL37(10.0.0.0/8).Ifthereis

nota

match,thesecondinstanceofroutemap1isinvoked,whichmatchesonallremainingroutesand

removesanycommunityattributes.ThismeansthatroutesmatchingACL37criteriawillhavea

communityattributesetto500:10,butalloftheotherroutesadvertisedto192.168.1.1willnot.

TheBGPpeer192.168.1.1willthenhavetheoptiontoapplyadesiredroutingpolicytoallroutes

arrivingfromthisrouterwiththecommunityattributesetto500:10.

set dampening

Thiscommandconfiguresrouteflapdampening,amechanismtocombatnetworkoverhead

whicharisesfromtheproliferationofuncontrolleddisconnecting/reconnectingnetworks.

Withroutedampening,youcanaddresstheseproblemroutesasfollows:

local-AS

Establishedcommunitywhichspecifiesthatroutescontainingthisvalue

shouldnotbeadvertisedtoexternalBGPpeers.

no-advertise

Establishedcommunitywhichspecifiesthatroutescontainingthisvalue

shouldnotbeadvertisedtoanyotherBGPpeers(internalorexternal).

no-export

Establishedcommunitywhichspecifiesthatroutescontainingthisvalue

shouldnotbeadvertisedoutsideaBGPconfederationboundary.

none

Removesanyexistingcommunities.

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