I have two sites with MPLS connections (SiteA) and (SiteB) these sites are also connected via a man connection to each other. In addition, I have 70 remote sites connecting into MPLS. If one of the remote sites goes down (circuit failure). SiteA and SiteB take over the network range of the remote site. When the remote site comes back up, SiteA and SiteB hold onto the network address causing routing issues for the remote site. The only way I have been able to fix this is by placing a route map on site A and site B mpls router denying the remote sites network range "in' and clearing BGP. During the period site A/B take over the address, the network range in question show the network range being learned via EIGRP until site a MPLS router where learns it from BGP from site b. Below is the connection and routing for siteA/B.
BGP AS 64551 BGP AS 64441
SiteA MPLS RTR SiteB MPLS RTR
EIGRP 100 EIGRP 100
site a router eigrp 100 redistribute bgp 64551 route-map BGP-TO-EIGRP network xx.xx.xx.33 0.0.0.0 network xx.xx.xx.128 0.0.0.7 network xx.xx.xx.1 0.0.0.0 default-metric 1000 100 255 1 1500 distribute-list 10 out GigabitEthernet0/0/0 no auto-summary ! router bgp 64551 no synchronization bgp log-neighbor-changes network 0.0.0.0 network xx.xx.146.0 redistribute connected redistribute eigrp 100 route-map EIGRP-TO-BGP neighbor xx.xx.xx.25 remote-as 65000 neighbor xx.xx.xx.25 route-map sitea-BGP-ROUTES-IN in neighbor xx.xx.xx.25 route-map siteb-ROUTES-OUT out default-information originate distribute-list 11 in GigabitEthernet0/0 no auto-summary
site b router eigrp 100 redistribute bgp 64550 route-map BGP-TO-EIGRP network xx.xx.xx.24 0.0.0.7 network xx.xx.xx.32 0.0.0.7 network xx.xx.xx.38 0.0.0.0 default-metric 1000 100 255 1 1500 no auto-summary ! router bgp 64550 no synchronization bgp log-neighbor-changes network xx.xx.xx.32 mask 255.255.255.240 network xx.xx.xx.38 mask 255.255.255.255 redistribute eigrp 100 neighbor xx.xx.xx.85 remote-as 65000 neighbor xx.xx.xx.85 route-map siteb-BGP-ROUTES-IN in neighbor xx.xx.xx.85 route-map sitea-ROUTES-OUT out default-information originate no auto-summary
I suspect when the remote site fails, site b advertises the remote network into BGP, thus site a learns it from BGP and the EIGRP timer can never expire that is why putting the route map "in" on both routers clears the routes out of the routing table. Can someone tell me what I have setup incorrectly and how to fix it?
In the BGP-to-EIGRP route-map you need to set a 'tag value' on the route. In the EIGRP-TO-BGP route-map you need to deny routes with the tag previously applied. This will prevent the route 'latching' behavior you are seeing.
Chris - Thank you for the reply. After researching this issue further, the symptoms have changed. Here is what I see.
Normal operation - Site A and Site B learn the 70 remote office networks from their respective MPLS routers.
Failure - If one of the remote sites goes down, once the network comes back up the route/network is learned and preferred from site a MPLS. Meaning if you go onto site B MPLS router the remote network is in the BGP routing table, but is not the preferred route "*" not "*>" , however the routing table shows the path to this remote site going over the L3 man link and out site a MPLS router. Again this only happens when the office goes down, to clear this issue I have been using route maps to deny this network "in" to both sites and soft resetting BGP seems to clear the issue. Thoughts?
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