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 HopMetric
> LocPrf Weight Path
> >*> 172.16.0.0 0.0.0.0
> 100 32768 (610) i
> >s>i172.16.1.0/24216.30.30.2 0
> 100 0 (610) i
> >s>i172.16.2.0/24216.30.30.2 0
> 100 0 (610) i
> >s>i172.16.3.0/24216.30.30.2 0
> 100 0 (610) i
> >*>i172.16.4.0/24216.30.30.2 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 HopMetric
> LocPrf Weight Path
> >*>i172.16.0.0 10.10.10.5
> 100 0 (610) i
> >*>i172.16.1.0/24216.30.30.2 0
> 100 0 (610) i
> >*>i172.16.2.0/24216.30.30.2 0
> 100 0 (610) i
> >*>i172.16.3.0/24216.30.30.2 0
> 100 0 (610) i
> >*>i172.16.4.0/24216.30.30.2 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
