Try as-set with aggregate-address, It will set the AS# on outgoing updates, in this case if R5 is advertising an aggregate to R7, R7 will re-advertise it back to the same as (i.e. 600 in this case of R5/R6), so to avoid this as-set key should be used, once using as-set when R7 tries to advertise it back to the as on R6, R6 will see its own AS# in the update so it will not accept the route from an outside AS,
Moreover. AS-SET keyword is usefull when you are doing proxy aggregation.. --- "Howard C. Berkowitz" wrote: > >Hello Group, > > > >I got a problem with BGP aggregate route being > advertised out to another AS, > >and then readvertised back to the original AS > through another entry router. > > > >R5_________R6 > > | > > R7 > > > >Basically an ethernet segment R5, R6, R7 on the > same subnet. R5 & R6 in > >AS600, and R7 in AS500. R5 sends out an aggregate > of 172.16.0.0/16 to R7, > >and then somehow R6 learns this aggregate route > also. > > > Several observations. > > I would advise against using no sync. As Peter van > Oene has pointed > out, it does't give a signficant performance benefit > in modern AS > topologies, and Juniper consciously doesn't even > have a knob for it. > > Next, I'm still confused what is being relearned, > and how this > creates a problem. Are you saying your routing > policy is such that > only the aggregating router should know about the > aggregate? You > want something like a NO-ADVERTISE policy on iBGP > but _not_ a > NO-EXPORT policy on eBGP? Why, if so? > > Again, I'm not seeing what problem is being caused, > but could a > blackhole local route for the aggregate, on R6, > solve it? > > > > >Configs: > > > >R5# > >router bgp 620 > > no synchronization > > bgp router-id 10.10.10.5 > > bgp log-neighbor-changes > > bgp confederation identifier 600 > > aggregate-address 172.16.0.0 255.255.0.0 as-set > suppress-map sup_map > > neighbor 10.10.10.4 remote-as 620 > > neighbor 10.10.10.4 update-source Loopback0 > > neighbor 10.10.10.7 remote-as 500 > > neighbor 10.10.10.7 ebgp-multihop 2 > > neighbor 10.10.10.7 update-source Loopback0 > > neighbor 10.10.10.7 route-map set_med out > > no auto-summary > >! > > > >BGP table version is 16, local router ID is > 10.10.10.5 > >Status codes: s suppressed, d damped, h history, * > valid, > best, i - > >internal > >Origin codes: i - IGP, e - EGP, ? - incomplete > > > > Network Next Hop Metric > LocPrf Weight Path > >*> 172.16.0.0 0.0.0.0 > 100 32768 (610) i > >s>i172.16.1.0/24 216.30.30.2 0 > 100 0 (610) i > >s>i172.16.2.0/24 216.30.30.2 0 > 100 0 (610) i > >s>i172.16.3.0/24 216.30.30.2 0 > 100 0 (610) i > >*>i172.16.4.0/24 216.30.30.2 0 > 100 0 (610) i > >*> 192.168.22.0 10.10.10.7 > 0 500 400 i > >R5# > > > > > >R6# > >router bgp 620 > > no synchronization > > bgp router-id 10.10.10.6 > > bgp log-neighbor-changes > > bgp confederation identifier 600 > > neighbor 10.10.10.4 remote-as 620 > > neighbor 10.10.10.4 update-source Loopback0 > > neighbor 10.10.10.7 remote-as 500 > > neighbor 10.10.10.7 ebgp-multihop 2 > > neighbor 10.10.10.7 update-source Loopback0 > > neighbor 10.10.10.7 route-map set_med out > > no auto-summary > >! > > > >BGP table version is 24, local router ID is > 10.10.10.6 > >Status codes: s suppressed, d damped, h history, * > valid, > best, i - > >internal > >Origin codes: i - IGP, e - EGP, ? - incomplete > > > > Network Next Hop Metric > LocPrf Weight Path > >*>i172.16.0.0 10.10.10.5 > 100 0 (610) i > >*>i172.16.1.0/24 216.30.30.2 0 > 100 0 (610) i > >*>i172.16.2.0/24 216.30.30.2 0 > 100 0 (610) i > >*>i172.16.3.0/24 216.30.30.2 0 > 100 0 (610) i > >*>i172.16.4.0/24 216.30.30.2 0 > 100 0 (610) i > >* i192.168.22.0 10.10.10.7 > 100 0 500 400 i > >*> 10.10.10.7 > 0 500 400 i > >R6# > > > >R7# > >router bgp 500 > > bgp router-id 10.10.10.7 > > bgp log-neighbor-changes > > neighbor 10.10.10.5 remote-as 600 > > neighbor 10.10.10.5 ebgp-multihop 2 > > neighbor 10.10.10.5 update-source Loopback0 > > neighbor 10.10.10.6 remote-as 600 > > neighbor 10.10.10.6 ebgp-multihop 2 > > neighbor 10.10.10.6 update-source Loopback0 > > neighbor 10.10.10.6 route-map change_weight in > > neighbor 10.10.10.8 remote-as 400 > > neighbor 10.10.10.8 ebgp-multihop 2 > > neighbor 10.10.10.8 update-source Loopback0 > > maximum-paths 2 > > no auto-summary > >! > > > >BGP table version is 9, local router ID is > 10.10.10.7 > >Status codes: s suppressed, d damped, h history, * > valid, > best, i - > >internal > >Origin codes: i - IGP, e - EGP, ? - incomplete > > > > Network Next Hop Metric > LocPrf Weight Path > >*> 172.16.0.0 10.10.10.5 > 0 600 i Sent out > to R7 > >* 10.10.10.5 > 0 600 i Some how > learnt it twice > >*> 172.16.1.0/24 10.10.10.6 > 150 600 i > >*> 172.16.2.0/24 10.10.10.6 > 0 600 i > >*> 172.16.3.0/24 10.10.10.6 > 0 600 i > >*> 172.16.4.0/24 10.10.10.5 50 > 0 600 i > >* 10.10.10.6 100 > 0 600 i > >*> 192.168.22.0 10.10.10.8 0 > 0 400 i > >R7# [EMAIL PROTECTED] __________________________________________________ Do You Yahoo!? Buy the perfect holiday gifts at Yahoo! Shopping. http://shopping.yahoo.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=27904&t=27822 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
