07-25-2011 09:24 AM - edited 03-04-2019 01:05 PM
i have two routers and one switch connected between the routers,eigrp is enabled in the lan and wan, one link connected on each router.routing protocol is eigrp..
A router is learning destination 10.155.10.0/24 and B router is learning destination 10.155.10.0/26 when i do a sh ip route 10.155.10.20, A router metric to reach destination is 200 and through B router is 500. which link will be prefered for destination 10.155.10.20 from the local lan.
Please advise. I need to prepare configuration before applying..
Solved! Go to Solution.
07-25-2011 11:42 AM
okie..last question, .i think if i put static route 10.155.10/24 pointing null0 200 and two network advertisemnet in BGP 10.155.10.100/32 and 10.155.10.0/24 will not help to pass specific 10.155.10.100/32 to its bgp neighbor..correct?
07-25-2011 11:44 AM
It's not about passing the advertisement. Its about what happens when the traffic arrives at B. Yes you can get B to advertise a /32 using a route to Null0 but when traffic arrives at B from C B will drop the packets and not forward on to A.
Jon
07-25-2011 11:51 AM
we apply static route to null0 with distance 200 so it will go to A router as ospf AD is less...correct me if i am wrong..
ip route 10.155.10.0 255.255.255.0 null0 200
07-25-2011 11:54 AM
Yes that would work for 10.155.10.0/24 but that is not the issue. The issue is that you need a route for 10.155.10.100 pointing to Null0 and that would black hole traffic.
Jon
07-25-2011 11:59 AM
okie...BGP router will not generate route for 10.155.10.100/32 unleass and until we put
ip route 10.155.10.100 255.255.255.255 null0 200
packect coming from C to B with destination 10.155.10.100 will drop on BGP router B as high prefix length prefer over AD even if we put AD 200 with null0 static route..
correct me if i am wrong..
07-25-2011 12:09 PM
Correct, that is why PBR is a better option to achieve what you want.
Jon
07-25-2011 12:11 PM
Thanks a lot it was so nice checking with you...have a nice day
07-25-2011 12:15 PM
BTW, how do we define redundancy in PBR...
on E router LAN interface need to apply PBR, I need to define next hop router C's WAN IP connects to E, but how traffic will switch over to router D when link between E and C went down?
router E and D lan is common
07-25-2011 12:21 PM
Just use 2 next-hops in PBR -
set ip next-hop x.x.x.x y.y.y.y
Jon
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