Strange problem with route selection when using eBGP and EIGRP
San Jose, California
June 17, 2013 1:24am CST
Question: I have a mixed WAN environment with WS-C3560X-24T-L WS-C3560X-24T-L both eBGP and EIGRP routes. The BGP routes should always take precedence, when they exist. If no BGP routes exist I want the router to fail over to using the EIGRP routes. So far, this works fine. The problem is, when the BGP route again becomes available (and the associated entry appears in the "sh ip bgp ... received-routes" output) the router is NOT relinquishing the EIGRP route. It remains in effect, showing as a "D" route int the route table even though there is a better ("B") route available. If I bounce EIGRP or the interface associated with it, the EIGRP route disappears and the BGP route reasserts itself, and everything will run correctly until the next time the BGP route disappears due to maintenance, line failure, etc. Any ideas? My router is (C2900-UNIVERSALK9-M), Version 15.3(1)T Here's the associated config interface Tunnel101 description VPN backup WAN interface bandwidth 7168 ip address 192.168.75.1 255.255.255.0 no ip redirects ip mtu 1500 ip flow ingress ip flow egress ip nhrp authentication ******* ip nhrp map multicast dynamic ip nhrp network-id 1001 ip tcp adjust-mss 1460 snmp ifindex persist tunnel source GigabitEthernet0/1.401 tunnel mode gre multipoint tunnel key 1001 tunnel protection ipsec profile wbprofile ! interface GigabitEthernet0/0 bandwidth 20480 ip address 172.17.29.1 255.255.255.252 no ip redirects no ip unreachables no ip proxy-arp ip flow ingress ip flow egress duplex full speed 100 snmp ifindex persist no cdp enable service-policy output qos-20meg router eigrp 101 distribute-list prefix backup-filter out Tunnel101 network 188.8.131.52 0.0.0.3 network 172.17.29.0 0.0.0.3 network 192.168.51.0 0.0.0.63 network 192.168.75.0 network 192.168.96.0 redistribute bgp 65261 metric 2000 1 255 1 1500 route-map ANB-to-WB-map router bgp 65261 bgp log-neighbor-changes redistribute connected redistribute static route-map WB-to-ANB-map redistribute eigrp 101 metric 1 route-map WB-to-ANB-map neighbor 172.17.29.2 remote-as 10970 neighbor 172.17.29.2 update-source GigabitEthernet0/0 neighbor 172.17.29.2 version 4 neighbor 172.17.29.2 soft-reconfiguration inbound neighbor 172.17.29.2 route-map ANB-to-WB-map in neighbor 172.17.29.2 route-map WB-to-ANB-map out ! ip bgp-community new-format route-map WB-to-ANB-map permit 10 match ip address prefix-list WB-to-ANB ! route-map ANB-to-WB-map permit 10 match ip address prefix-list ANB-to-WB ip prefix-list backup-filter seq 5 deny 172.17.29.0/24 ge 25 ip prefix-list backup-filter seq 10 deny 192.168.51.0/24 ge 25 ip prefix-list backup-filter seq 15 deny 192.168.52.0/24 ge 25 ip prefix-list backup-filter seq 20 deny 192.168.95.0/24 ge 25 ip prefix-list backup-filter seq 25 permit 0.0.0.0/0 ge 1 ip prefix-list ANB-to-WB description routes permitted from ANB ip prefix-list ANB-to-WB seq 5 permit 10.0.0.0/8 ge 9 ip prefix-list ANB-to-WB seq 10 permit 172.31.252.0/24 ip prefix-list ANB-to-WB seq 15 permit 172.31.253.0/24 ip prefix-list ANB-to-WB seq 20 permit 192.168.3.0/24 ip prefix-list ANB-to-WB seq 25 permit 192.168.96.8/32 ip prefix-list ANB-to-WB seq 30 permit 192.168.96.9/32 ip prefix-list ANB-to-WB seq 35 permit 192.168.96.10/32 ip prefix-list ANB-to-WB seq 40 permit 192.168.96.11/32 ip prefix-list ANB-to-WB seq 45 permit 192.168.96.12/32 ip prefix-list ANB-to-WB seq 50 permit 192.168.96.13/32 ip prefix-list ANB-to-WB seq 55 permit 192.168.10.0/24 ip prefix-list ANB-to-WB seq 60 permit 192.168.4.0/24 ip prefix-list ANB-to-WB seq 65 permit 192.168.6.0/24 ip prefix-list ANB-to-WB seq 70 permit 192.168.96.15/32 ip prefix-list ANB-to-WB seq 75 permit 192.168.96.16/32 ip prefix-list ANB-to-WB seq 80 permit 192.168.96.17/32 ip prefix-list ANB-to-WB seq 85 permit 192.168.17.0/24 ip prefix-list ANB-to-WB seq 90 permit 192.168.96.1/32 ip prefix-list ANB-to-WB seq 95 permit 192.168.96.2/32 ip prefix-list ANB-to-WB seq 100 permit 192.168.96.5/32 ip prefix-list ANB-to-WB seq 105 permit 0.0.0.0/0 ip prefix-list ANB-to-WB seq 110 permit 192.168.96.249/32 ip prefix-list WB-to-ANB description routes advertised to ANB ip prefix-list WB-to-ANB seq 3 deny 192.168.3.252/32 ip prefix-list WB-to-ANB seq 5 permit 192.168.0.0/19 ge 24 ip prefix-list WB-to-ANB seq 10 permit 192.168.192.0/19 ge 24 ip prefix-list WB-to-ANB seq 15 permit 192.168.98.0/24 ip prefix-list WB-to-ANB seq 20 permit 192.168.51.0/26 ip prefix-list WB-to-ANB seq 25 permit 192.168.99.0/24 Answer: I faced excatly the same problem some time ago. If you need to keep the prefix redistributed from EIGRP to BGP for some reason (as I did) you can make the eBGP prefix to win by changing BGP attributes. By default the prefix redistributed from EIGRP to BGP gets the weight=32768 attributes value. So you can set this value to 0 by the route-map used for redistribution and increase the local preference, e.g., to be sure it wins. Or you can set the weight of eBGP prefix to 40000 by another route-map. more information ,you can visit
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