Allied Telesis x908, X8100 manual Add that ACL as a distribute-list in-filter on the neighbor

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8.Add that ACL as a distribute-list in-filter on the neighbor:

Examples

With this combination, neither 156.23.4.32/27 nor 156.34.4.144/28 appear in the IP route table. The route 156.23.4.32/27 is dropped by the route map filter, and the route 156.34.4.144/28 is dropped by the ASPath-list filter.

BGP#show ip route

Codes: C - connected, S - static, R - RIP, B - BGP O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2

* - candidate default

B45.0.0.0/8 [20/0] via 45.45.45.46, vlan1, 00:06:39

C45.45.45.0/24 is directly connected, vlan1

B52.0.0.0/8 [20/0] via 45.45.45.46, vlan1, 00:06:39

C64.0.0.0/4 is directly connected, vlan64

B156.23.4.0/29 [20/0] via 45.45.45.46, vlan1, 00:06:39

B 156.23.4.8/29 [20/0] via 45.45.45.46, vlan1, 00:06:39

7.Now create an ACL that drops the route 156.23.4.0/28, and allows all others. access-list standard list3 deny 156.23.4.0/28 access-list standard list3 permit any

8.Add that ACL as a distribute-list in-filter on the neighbor:

router bgp 34567 redistribute connected

neighbor 45.45.45.46 remote-as 34568

neighbor 45.45.45.46 distribute-list list3 in neighbor 45.45.45.46 route-map com in neighbor 45.45.45.46 filter-list list1 in

9.Shut down the neighbor, and then bring it up again:

awplus(config-router)#neighbor 45.45.45.46 shutdown awplus(config-router)#neighbor 45.45.45.46 no shutdown

Then all the 156.23.4.x routes are filtered out. The distribute-list filter drops both the routes 156.23.4.0/29 and 156.23.4.8/29 because the effect of the distribute-list filter is to drop all routes within the address range covered by 156.23.4.0/28, that have a prefix- length of 28 or longer.

BGP#show ip route

Codes: C - connected, S - static, R - RIP, B - BGP O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2

* - candidate default

B45.0.0.0/8 [20/0] via 45.45.45.46, vlan1, 00:16:21

C45.45.45.0/24 is directly connected, vlan1

B52.0.0.0/8 [20/0] via 45.45.45.46, vlan1, 00:16:21

C64.0.0.0/4 is directly connected, vlan64

Page 42 Use Route Maps and Other Filters to Filter and Alter BGP and OSPF Routes

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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 updates BGP Concepts and TerminologyBGP peers 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 Confirming the neighbor relationship AlliedWare switchawplus#show ip route BGP Configuring Distribute Filters About ACLsUsing ACLs as filters Example Distribute filtersFilter out one particular route from a neighbor Filter out a range of prefix lengths awplusconfig# neighbor 45.45.45.46 distribute-list list2 in 3. Check that the IP route table now includes all the routes6. Shut down the neighbor, and then bring it up again Use a numbered ACL instead of a named ACL awplusconfig-router# do show ip route BGP Configuring AS Path Filters AS path listsUsing AS path lists as path filters Example AS path filtersDiscard or allow routes from a neighbor 4. Shut down the neighbor, and then bring it up again a neighbor7. Shut down the neighbor, and then bring it up again Another example An outgoing filter that uses an AS-path listBGP Configuring AS Path Filters BGP Configuring Prefix Filters About prefix listsMask length 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 BGP Configuring Route Maps Structure of a route mapConfiguring a match clause ClausesAn AS path list A community list CaseOne 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 bgp add ip routem=com entry=1 set commmun=8989 1. Configure the AW peer to send out a community number The 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 configuration Route map configurationBGP Route Map Filtering Example set local-preference route-map outdef permit OSPF Configuring Route Maps for Filtering and Modifying OSPF Routes MetricInterface A prefix, by using a prefix list A prefix, by using an ACLExternal route type OSPF Applying Route Maps  Set the metric, by using the command set metric

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