Unanswered Question
Aug 23rd, 2010
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Can somebody help us to diagnostic these problem between static and dynamic routing?

We have a router 3845 connected to a IPVPN Cloud using BGP routing protocol. This rotuer announce the internal network: / 16.

There is a main router connected to the same IPVPN Cloud WHICH is announcing the network: / 24 to all other routers including the 3845 router.

At the physical location of 3845 router, there is a backup link that point to network: / 16 but with a higher distance metric 250 and this route is propagated to IPVPN Cloud.

In normal condition, the router 3845 learn the network: / 16 trough backup link instead using the route propagated through IPVPN Cloud.


If the router 3845 learns the / 24 through IPVPN with a distance metric of 240 and it announce the same network / 24 with a distance metric of: 250 why users take the backup route?

What i can do so users can take the route through IPVPN Cloud instead back route ?

The configuration at 3845 is:


ip prefix-list PVIDA seq 20 permit

route-map PVIDA permit 10
match ip address prefix-list PVIDA
set community 6147:70

router bgp 65515
no synchronization
bgp log-neighbor-changes
network mask

redistribute static route-map PVIDA

The sh ip router command at 3845 router is:

RansaCOM_47220#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, 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
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is to network

B [20/0] via, 1d06h
B [20/0] via, 1d06h
B [20/0] via, 1d06h
S [250/0] via
B [20/0] via, 1d06h
B [20/0] via, 1d06h

Thanking you in advanceyour address.

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Lei Tian Mon, 08/23/2010 - 17:47
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  • Cisco Employee,


Do a 'show ip bgp', I think on 3845, you will see 2 routes in BGP table. One is local generated from redistribution, the other is learned via BGP. The local one becomes the best because higher weight.

If you want prefer the one learned from BGP, you can apply a route-map to the neighbor and assign higher weight to prefix


Lei Tian


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