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Allied Telesis X8100, x908 First, enter BGP router mode for the AS. The prompt should look like

Models: X8100 x908

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BGP: Applying Distribute, Path, Prefix, and Route Map Filters to a Peer

BGP: Applying Distribute, Path, Prefix, and Route Map Filters to a Peer

Distribute filters, path filters, prefix filters, and route maps can all be applied to a BGP peer configuration for both incoming and outgoing updates. However, you cannot combine distribute filters (ACLs) and prefix filters.

First, enter BGP router mode for the AS. The prompt should look like:

awplus(config-router)#

Then use the following commands to apply:

an ACL to filter incoming route updates:

neighbor <ipadd> distribute-list <acl> in

a path list to filter incoming route updates:

neighbor <ipadd> filter-list <list-name> in

a prefix list to filter incoming route updates:

neighbor <ipadd> prefix-list <list-name> in

a route map to filter incoming route updates or alter their attributes: neighbor <ipadd> route-map <map-name> in

an ACL to filter outgoing route updates:

neighbor <ipadd> distribute-list <acl> out

a path list to filter outgoing route updates:

neighbor <ipadd> filter-list <list-name> out

a prefix list to filter outgoing route updates:

neighbor <ipadd> prefix-list <list-name> out

a route map to filter outgoing route updates or alter their attributes: neighbor <ipadd> route-map <map-name> out

You can also use an AS path list, prefix list or ACL in a route map, instead of applying it directly as a filter.

As mentioned in "Hierarchy of the Different Filters" on page 8, if you configure multiple types of filter, the switch applies the route maps last. This is true in both the incoming and outgoing directions.

Use Route Maps and Other Filters to Filter and Alter BGP and OSPF Routes Page 35

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Allied Telesis X8100, x908 manual First, enter BGP router mode for the AS. The prompt should look like

Contents

Technical Guide IntroductionBGP Applying Route Maps to Imported Routes ContentsIntroduction Which products and software version does it apply to?Which products and software version does it apply to? Related How To NotesBGP peers BGP updatesBGP Concepts and Terminology Next-hop Update attributesOrigin AS-pathDistribute filters Access Control List ACL filtersBGP Overview of the Available Filter Types Filter typesDifference and Relationship in BGP Examples for filtering BGP Update messages Example AS path filters on page  Example Prefix filters on page Hierarchy of the Different FiltersBGP Example  Example Distribute filters on pageBasic configuration awplus#show ip route Confirming the neighbor relationshipAlliedWare switch AlliedWare Plus switchAbout ACLs BGP Configuring Distribute FiltersFilter out one particular route from a neighbor Using ACLs as filtersExample Distribute filters Filter out a range of prefix lengths 3. Check that the IP route table now includes all the routes awplusconfig# neighbor 45.45.45.46 distribute-list list2 inawplusconfig-router# do show ip route awplusconfig# router bgpUse a numbered ACL instead of a named ACL 4. Check that the IP route table no longer includes 52.0.0.0/8 awplusconfig-router# do show ip routeAS path lists BGP Configuring AS Path FiltersDiscard or allow routes from a neighbor Using AS path lists as path filtersExample AS path filters 7. Shut down the neighbor, and then bring it up again 4. Shut down the neighbor, and then bring it up againa neighbor An outgoing filter that uses an AS-path list Another exampleBGP Configuring AS Path Filters Mask length BGP Configuring Prefix FiltersAbout prefix lists awplusconfig-router# neighbor neighbor prefix-list list-name out Using prefix lists as prefix filtersExample Prefix filters awplusconfig-router# neighbor neighbor prefix-list list-name inFilter out a range of different prefix lengths awplusconfig-router# do show ip route BGP Configuring Prefix FiltersStructure of a route map BGP Configuring Route MapsAn AS path list Configuring a match clauseClauses Case A community listCase One or more prefixes, by using an ACL One or more prefixes, by using a prefix listA metric the MED attribute Configuring a set clauseA next hop address An originset community community-values additive set ip next-hop ipadd set weightset atomic-aggregate set extcommunity rtsoo ext-comm-numberA match clause and one or more set clauses The effect of different combinations of clausesOne match clause with an action No match clause and one or more set clausesRouter AS Update from PeerUpdate 1 to Peer Update 2 to PeerFirst, enter BGP router mode for the AS. The prompt should look like awplusconfig-route-map#set metric ExamplesExample B Match on a prefix-list that denies an entry awplusconfig#ip prefix-list test1 permit 52.0.0.0/84. Apply this route map as the in route map on the neighbor awplusconfig-route-map#router bgp Example D Matching on a next-hop prefix-listExample E Prepending AS numbers awplusconfig-route-map#match ip addressset bgp peer=45.45.45.45 outroutemap=com sendcommunity=yes 1. Configure the AW peer to send out a community numberThe routes coming from that peer has community add ip routem=com entry=1 set commmun=8989BGP#show ip route set bgp peer=45.45.45.45 outroutemap=mixed sendcommunity=yes 8. Add that ACL as a distribute-list in-filter on the neighbor route-map marker permit Examples Route maps ACLs Path filters Prefix filtersSyntax BGP Applying Route Maps to Imported Routesnetwork neighbor default-originateOther Uses of Route Maps neighbor unsuppress-mapBGP Route Map Filtering Example BGP configurationRoute map configuration set local-preference route-map outdef permit Configuring a match clause OSPF Configuring Route Maps for Filtering and Modifying OSPF RoutesMetric InterfaceConfiguring a set clause A prefix, by using a prefix listA prefix, by using an ACL External route type Set the metric, by using the command set metric OSPF Applying Route Maps