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Allied Telesis x908 Contents, Introduction, Which products and software version does it apply to?

Models: X8100 x908

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	Introduction
Contents
Introduction	1
Related How To Notes	3
Which products and software version does it apply to?	3
BGP: Concepts and Terminology	4
BGP peers	4
BGP updates	4
Update attributes	5
BGP: Overview of the Available Filter Types	6
Filter types	6
Hierarchy of the Different Filters	8
BGP: Example	8
Basic configuration	9
BGP: Configuring Distribute Filters	11
About ACLs	11
Using ACLs as filters	12
Example: Distribute filters	12
BGP: Configuring AS Path Filters	17
AS path lists	17
Using AS path lists as path filters	18
Example: AS path filters	18
BGP: Configuring Prefix Filters	22
About prefix lists	22
Mask length	22
Using prefix lists as prefix filters	23
Example: Prefix filters	23
BGP: Configuring Route Maps	26
Structure of a route map	26
Clauses	27
Configuring a match clause	27
Configuring a set clause	30
The effect of different combinations of clauses	33
BGP: Applying Distribute, Path, Prefix, and Route Map Filters to a Peer	35
Examples	36
BGP: Applying Route Maps to Imported Routes	46
Syntax	46
Other Uses of Route Maps	47
neighbor default-originate	47
neighbor unsuppress-map	47
network	47
show ip bgp	47

Page 2 Use Route Maps and Other Filters to Filter and Alter BGP and OSPF Routes

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Allied Telesis x908, X8100 manual Contents, Introduction, Which products and software version does it apply to?

Contents

Introduction Technical GuideWhich products and software version does it apply to? ContentsIntroduction BGP Applying Route Maps to Imported RoutesRelated How To Notes Which products and software version does it apply to?BGP peers BGP updatesBGP Concepts and Terminology AS-path Update attributesOrigin Next-hopFilter types Access Control List ACL filtersBGP Overview of the Available Filter Types Distribute filtersExamples for filtering BGP Update messages Difference and Relationship in BGP Example Distribute filters on page Hierarchy of the Different FiltersBGP Example  Example AS path filters on page  Example Prefix filters on pageBasic configuration AlliedWare Plus switch Confirming the neighbor relationshipAlliedWare switch awplus#show ip routeBGP Configuring Distribute Filters About ACLsFilter out one particular route from a neighbor Using ACLs as filtersExample Distribute filters Filter out a range of prefix lengths awplusconfig# router bgp awplusconfig# neighbor 45.45.45.46 distribute-list list2 inawplusconfig-router# do show ip route 3. Check that the IP route table now includes all the routesUse a numbered ACL instead of a named ACL awplusconfig-router# do show ip route 4. Check that the IP route table no longer includes 52.0.0.0/8BGP Configuring AS Path Filters AS path listsDiscard 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 Another example An outgoing filter that uses an AS-path listBGP Configuring AS Path Filters Mask length BGP Configuring Prefix FiltersAbout prefix lists awplusconfig-router# neighbor neighbor prefix-list list-name in Using prefix lists as prefix filtersExample Prefix filters awplusconfig-router# neighbor neighbor prefix-list list-name outFilter out a range of different prefix lengths BGP Configuring Prefix Filters awplusconfig-router# do show ip routeBGP Configuring Route Maps Structure of a route mapAn AS path list Configuring a match clauseClauses Case A community listCase One or more prefixes, by using a prefix list One or more prefixes, by using an ACLAn origin Configuring a set clauseA next hop address A metric the MED attributeset community community-values additive set extcommunity rtsoo ext-comm-number set weightset atomic-aggregate set ip next-hop ipaddNo match clause and one or more set clauses The effect of different combinations of clausesOne match clause with an action A match clause and one or more set clausesUpdate 2 to Peer Update from PeerUpdate 1 to Peer Router ASFirst, enter BGP router mode for the AS. The prompt should look like awplusconfig#ip prefix-list test1 permit 52.0.0.0/8 ExamplesExample B Match on a prefix-list that denies an entry awplusconfig-route-map#set metric4. Apply this route map as the in route map on the neighbor awplusconfig-route-map#match ip address Example D Matching on a next-hop prefix-listExample E Prepending AS numbers awplusconfig-route-map#router bgpadd ip routem=com entry=1 set commmun=8989 1. Configure the AW peer to send out a community numberThe routes coming from that peer has community set bgp peer=45.45.45.45 outroutemap=com sendcommunity=yesBGP#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 ACLs Path filters Prefix filters Route mapsBGP Applying Route Maps to Imported Routes Syntaxneighbor unsuppress-map neighbor default-originateOther Uses of Route Maps networkBGP Route Map Filtering Example BGP configurationRoute map configuration set local-preference route-map outdef permit Interface OSPF Configuring Route Maps for Filtering and Modifying OSPF RoutesMetric Configuring a match clauseExternal route type A prefix, by using a prefix listA prefix, by using an ACL Configuring a set clauseOSPF Applying Route Maps  Set the metric, by using the command set metric