Re: BGP routes discrepancy

I am not exactly sure what you have hear but since you have a "hub and spoke" and the spokes are in the same AS, you might need to add "neighbor x.x.x.x allow-as in" or on the HUB "neighbor x.x.x.x as-override"

On Jun 4, 2010, at 7:28 AM, Jules Eyabane wrote:

> i have a small lab of 3 routers in dual-homed hub & spoke :R1, R2, R3. R1 is
> the Hub. R2 & R3 are in the same AS, and R1 is acting as the ISP. each spoke
> advertises 1 network (R2=172.16.32.x and R1=172.16.64.x), and the ISP (R1)
> advertises 3 networks: 192.168.100.0., 1.1.1.0, and 11.11.11.0. R1 and R2
> have an iBGP peering.
>
> my questions is: how come R1 shows 5 prefixes being sent to R2 vs 3 sent to
> R3? more over, both R2 and R3 show only 3 prefixes being learned from R1.
> all seem to checkout on R3 (showing only 3 prefixes sent/received), but the
> output on R2 puzzles me a bit. shouldn't it reflect 3 prefixes just like R3?
> There are no filters whatsoever on any of the routers, and i have done a
> hard reset a couple of times. please advise.
> Thanks in advance for your input
>
> pertinent config below:
> ===
> R1: 192.168.100.1
> ===
>
> R1-ISP#sho ip bgp neighbors 172.16.64.1 advertised-routes
> BGP table version is 6, local router ID is 192.168.100.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 1.1.1.0/24 0.0.0.0 0 32768 i
> *> 11.11.11.0/24 0.0.0.0 0 32768 i
> *> 172.16.32.0/24 172.16.32.1 0 0 64512 i
> *> 172.16.64.0/24 172.16.32.1 0 64512 i
> *> 192.168.100.0 0.0.0.0 0 32768 i
> *
> Total number of prefixes 5*
>
> !!!!
> R1-ISP#sho ip bgp neighbors 172.16.32.1 advertised-routes
> BGP table version is 6, local router ID is 192.168.100.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 1.1.1.0/24 0.0.0.0 0 32768 i
> *> 11.11.11.0/24 0.0.0.0 0 32768 i
> *> 192.168.100.0 0.0.0.0 0 32768 i
>
> *Total number of prefixes 3*
> !!!!
> !!!!!!
>
> R1-ISP#sho run | be router bgp
> router bgp 200
> no synchronization
> bgp log-neighbor-changes
> network 1.1.1.0
> network 1.1.1.0 mask 255.255.255.0
> network 11.11.11.0
> network 11.11.11.0 mask 255.255.255.0
> network 192.168.100.0
> aggregate-address 2.2.2.0 255.255.255.0 as-set summary-only
> neighbor 172.16.32.1 remote-as 64512
> neighbor 172.16.32.1 ebgp-multihop 2
> neighbor 172.16.32.1 update-source Loopback0
> neighbor 172.16.64.1 remote-as 64512
> neighbor 172.16.64.1 ebgp-multihop 2
> neighbor 172.16.64.1 update-source Loopback0
> no auto-summary
> !
> ===
> R2: 172.16.64.1
> ===
>
> R2-SanJose1#sho ip bgp neighbo 192.168.100.1 received-routes
> BGP table version is 67, local router ID is 172.16.64.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 1.1.1.0/24 192.168.100.1 0 0 200 i
> *> 11.11.11.0/24 192.168.100.1 0 0 200 i
> *> 192.168.100.0 192.168.100.1 0 0 200 i
>
> *Total number of prefixes 3*
> R2-SanJose1#
>
> ===
> R3: 172.16.32.1
> ===
> R3-SanJose2#sho ip bgp neighbo 192.168.100.1 received-routes
> BGP table version is 43, local router ID is 172.16.32.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 1.1.1.0/24 192.168.100.1 0 0 200 i
> *> 11.11.11.0/24 192.168.100.1 0 0 200 i
> *> 192.168.100.0 192.168.100.1 0 0 200 i
>
> Total number of prefixes 3
>
>
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Received on Fri Jun 04 2010 - 08:19:37 ART