- Blue, 1500 points or more
If I redistribute a static route into a dynamic routing protocol, that static route will lose its AD and take on the AD of the dynamc routing protocol. Correct?
I have 2 separate edge routers (A and B) that connect to the same router (C) on the back end of it. I want to make router A the primary route to network 10.0.0.0 and router B the alternate route.
If I create a static route (ip route 10.0.0.0 255.0.0.0 192.168.1.1) on both those routers and redistribute into, say, eigrp, giving the static route on router B an AD of, say, 200, is meaningless. Correct?
I say this because each static route will be converted to an external eigrp route and take on an AD of 170. So, C will receive 2 comparable, equal-cost routes with the same AD and place both of them in its routing table. Correct?
So, if I want to make router B the alternate route, I must manipulate the seed metrics on routers A and B so that router C can receive both eigrp routes and use the metrics as the decision maker as to which route will be placed in C's routing table -- you know, the usual way it's done.
If all this is correct, I am wondering why I see static routes being redistributed into BGP on 2 separate edge routers (at a client site) -- but one with an AD higher than the other. No BGP attributes are being manipulated at the redistribution point with, say, a route map. So, whats the point? A goof-up?
It has taken me a while to sort through this and to realize that I was not on the right path in asking about the route map PREPEND-AS. The question is not really what B advertises to A but is what B advertises to other neighbors.
So I re-evaluated what you have told us about this and see a different issue. I will start my explanation by referring to a comment in one of your posts:
"Take note that Switch A advertises to Switch B and Switch B accepts that advert"
I now believe that this is not really the case. The significant clue is in this output:
ve01>sh ip bgp 172.27.88.64
BGP routing table entry for 172.27.88.64/27, version 0
Paths: (1 available, no best path)
Not advertised to any peer
64716 64562 64725, (received-only)
In particular notice that there is no best path and notice that the prefix is marked as
received-only. I had to do some digging to find that received-only means that the policy has rejected this path. However, the router has stored the paths because you have configured soft-reconfiguration inbound for the neighbor.
So what would cause the policy to reject the path? I believe that the answer is in:
neighbor 10.182.80.3 route-map ALLOWED.FROM.ESM in
So can you post the route map ALLOWED.FROM.ESM
For details of received-only you can use this link:
It does appear that the more specific 172.27.88.64/27 is not advertised because of advertising the summary. In general my experience has been like yours and configuration of a summary does not necessarily suppress advertisement of the more specific routes. Without more information from the switch I am not sure that I can explain it well. Perhaps it is enough to say that the more specific is not advertised because of the summary - or perhaps you may want to post the switch config so we can dig into it more deeply.
Ok. Let's say Router A advertises the route to C and C advertises it to B. B has two options - External EIGRP (from C) or floating static route (distance of 200) - it would choose EIGRP (distance of 170) over the static route because of the lower admin distance. Hence, all trafffic would flow through A.
If A becomes unreachable then B would start using the static route and advertise the same to C and it would become the alternate route for C till A becomes reachable again.
Your goal of trying to do primary and backup route would work in this situation excepting that C wouldn't have both routes in the routing table at any given time when B's static route is configured with a higher admin distance. If you want C learn both routes and choose one over the other or load balance the traffic then configure the static route of both A and B with the same distance or default (1).
Hope I understood your requirement correctly. If there's any part that I misunderstood please let me know what that is.