Allied Telesis x908, X8100 manual Examples

Page 44

Manual background

Examples

BGP route table

Flags: >=Best route for the given prefix, *=Unreachable next hop, W=Withdrawn

m=Community, a=Aggregate route, s=Aggregate Suppressed, D=Damped Learned from: L=Local, e=eBGP Peer, i=iBGP Peer, c=Confederate

Peer

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

Fl Prefix	Next hop	Origin	MED	Local pref
Path
Originator	Cluster List

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

> 45.0.0.0/8	0.0.0.0	IGP	-	100
EMPTY
L -	-
> 45.45.45.0/24	45.45.45.45	INCOMPLETE	-	100
SEQ 34567;
e -	-
> 52.0.0.0/8	0.0.0.0	IGP	-	100
EMPTY
L -	-
> 64.0.0.0/4	45.45.45.45	INCOMPLETE	-	100
SEQ 34567;
e -	-
> 156.23.4.0/29	52.34.5.4	INCOMPLETE	-	100
EMPTY
L -	-
> 156.23.4.8/29	52.45.45.45	INCOMPLETE	-	100
EMPTY
L -	-
> 156.23.4.32/27	52.45.45.45	INCOMPLETE	-	100
EMPTY
L -	-
> 156.23.4.144/28	52.45.45.45	INCOMPLETE	-	100
EMPTY
L -	-
> 192.34.23.0/26	45.45.45.45	INCOMPLETE	-	100
SEQ 34567;
e -	-
> 192.34.23.32/29	45.45.45.45	INCOMPLETE	-	100
SEQ 34567 7822;	-------------------------------------------------
e -	-
> 192.34.23.192/27	45.45.45.45	INCOMPLETE	-	100
SEQ 34567;
e -	-

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

Page 44 Use Route Maps and Other Filters to Filter and Alter BGP and OSPF Routes

Image 44

Contents Introduction Technical GuideContents IntroductionWhich products and software version does it apply to? 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 Update attributes OriginAS-path Next-hopAccess Control List ACL filters BGP Overview of the Available Filter TypesFilter types Distribute filtersExamples for filtering BGP Update messages Difference and Relationship in BGPHierarchy of the Different Filters BGP Example Example Distribute filters on page  Example AS path filters on page  Example Prefix filters on pageBasic configuration awplus#show ip route Confirming the neighbor relationshipAlliedWare switch BGP 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 6. Shut down the neighbor, and then bring it up again awplusconfig# neighbor 45.45.45.46 distribute-list list2 in3. Check that the IP route table now includes all the routes Use a numbered ACL instead of a named ACL awplusconfig-router# do show ip route BGP 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 Using prefix lists as prefix filters Example Prefix filtersawplusconfig-router# neighbor neighbor prefix-list list-name in 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 mapAn AS path list Configuring a match clauseClauses A community list CaseOne or more prefixes, by using a prefix list One or more prefixes, by using an ACLConfiguring a set clause A next hop addressAn origin A metric the MED attributeset community community-values additive set weight set atomic-aggregateset extcommunity rtsoo ext-comm-number set ip next-hop ipaddThe effect of different combinations of clauses One match clause with an actionNo match clause and one or more set clauses A match clause and one or more set clausesUpdate from Peer Update 1 to PeerUpdate 2 to Peer Router ASFirst, enter BGP router mode for the AS. The prompt should look like Examples Example B Match on a prefix-list that denies an entryawplusconfig#ip prefix-list test1 permit 52.0.0.0/8 awplusconfig-route-map#set metric4. Apply this route map as the in route map on the neighbor Example D Matching on a next-hop prefix-list Example E Prepending AS numbersawplusconfig-route-map#match ip address awplusconfig-route-map#router bgp1. Configure the AW peer to send out a community number The routes coming from that peer has communityadd ip routem=com entry=1 set commmun=8989 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 default-originate Other Uses of Route Mapsneighbor unsuppress-map 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 External route type A prefix, by using a prefix listA prefix, by using an ACL OSPF Applying Route Maps  Set the metric, by using the command set metric

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