[c-nsp] BGP/EIGRP Route Determination

[Brian Tate]

Thanks for the response, but I'm confused by it - I don't think I want to lower the EIGRP AD, as I don't want it to be the preferred route.
Your correct, the external BGP AD is lower [20] than the EIGRP learned route [90]... which is why it does install BGP as the preferred route, initially.
But upon failure at Rtr-A, Rtr-B loses the external BGP route, and installs the EIGRP learned route... as it should.
But upon restore of Rtr-A, Rtr-B is not always returning to the external BGP route - if I reset the EIGRP adjacency on Rtr-B, then it will install the BGP route.

Here are my routing table outputs for the 10.60.0.0/16 summarized route, on Rtr-B:
D       10.60.0.0 [90/6436112] via X.X.X.X, 00:00:58, Vlan999   (only present in the routing table when the issue occurs)
B       10.60.0.0 [20/0] via Y.Y.Y.Y, 00:00:02  (normally present, and re-installed after clear eigrp adjacency)

Here is the EIGRP topology in a normal state:
sh ip eigr top 10.60.0.0/16
EIGRP-IPv4 Topology Entry for AS(1)/ID(192.168.0.19) for 10.60.0.0/16
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 32000
  Descriptor Blocks:
 Y.Y.Y.Y, from Redistributed, Send flag is 0x0
      Composite metric is (32000/0), route is External
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 250 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 0
        Originating router is 192.168.0.19
      External data:
        AS number of route is 68500
        External protocol is BGP, external metric is 0
        Administrator tag is 13000
  X.X.X.X (Vlan999), from X.X.X.X, Send flag is 0x0
      Composite metric is (6436112/6435856), route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 250410 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2


Also, here is the BGP detail for the same route
- This is the BGP entry when the issue occurs - before clearing EIGRP neighbors
      Network          Next Hop            Metric LocPrf Weight Path
*> 10.60.0.0/16     X.X.X.X            6436112         32768 ?

- After clearing EIGRP, and the desired path -
*> 10.60.0.0/16     Y.Y.Y.Y                                  50000 13000 68500 ?

Thanks
- Tate


> 
> I've seen this before and it was due to the bgp routes having a lower admin distance (external). Orignally the euro adjacency would have been established first so eirgp's routes were selected.
> 
> You need to modify rtr b so eirgp has a better admin distance then external bgp
>