01-05-2009 09:58 PM - edited 03-04-2019 03:20 AM
For the two routers(located in different location), they are learning the same BGP routes, but I'd like to redistribute BGP into the EIGRP so that router B redistributed BGP is always preferred over Router A redistributed BGP routes. Does this metric configuration look ok? should this work? Thanks.
//Router A
router eigrp 109
redistribute static
redistribute bgp 64806 metric 1024 1000 250 1 1500
no auto-summary
network 172.20.0.0
network 172.24.0.0
network 176.20.0.0
network 192.168.0.0
network 192.168.10.0
//Router B
router eigrp 109
redistribute static
redistribute bgp 64808 metric 2048 1000 255 1 1500
no auto-summary
network 172.20.0.0
network 172.24.0.0
network 176.20.0.0
network 192.168.0.0
network 192.168.1.0
Solved! Go to Solution.
01-05-2009 11:44 PM
hi Shawkat,
To achieve the objective it's better you keep the bandwidth same on both router and just modify delay. In the above configuration, the advertised distance from Router A will be much larger that it will never be considered as a feasible successor in EIGRP.
So keep that bandwidth same on both routers and just modify the delay by 1 or 2.
eg: 999 on Router B and 1000 on Router A
RTR B
redistribute bgp 64808 metric 2048 999 255 1 1500
RTR A
redistribute bgp 64808 metric 2048 1000 255 1 1500
HTH
Lejoe
01-05-2009 11:44 PM
hi Shawkat,
To achieve the objective it's better you keep the bandwidth same on both router and just modify delay. In the above configuration, the advertised distance from Router A will be much larger that it will never be considered as a feasible successor in EIGRP.
So keep that bandwidth same on both routers and just modify the delay by 1 or 2.
eg: 999 on Router B and 1000 on Router A
RTR B
redistribute bgp 64808 metric 2048 999 255 1 1500
RTR A
redistribute bgp 64808 metric 2048 1000 255 1 1500
HTH
Lejoe
01-06-2009 01:46 PM
Thanks a lot Lejoe.
I will try your approach and update you.
Cheers.
01-07-2009 05:06 PM
Thanks Lejoe, this trick worked.
02-23-2009 10:01 PM
There is a problem again. When we lost the RTR B, all traffic switched through RTR A(exactly as we wanted), but when RTR B was restored, routes were still travelling via RTR A. I had to manually stop BGP routing on RTR A to get the reroutes working properly.
How can this be achieve automatically when it detects that default path is restored?
02-24-2009 12:23 AM
Hi,
after the router B restore, did you see the BGP prefixes redistributed to the EIGRP topology on router B?
Are the router A and B receiving the BGP prefixes from the same router in a different AS? Or from different neighbors? Is there any BGP session between routers A and B?
BR,
Milan
02-24-2009 12:29 AM
Are you by any chance redistibuting EIGRP back into BGP as well?
Narayan
02-24-2009 04:10 AM
Yes I am redistributing EIGRP into BGP as well.
Both router has:
redistribute eigrp 109 metric 1
do you think I should change the metric?
02-24-2009 04:02 AM
Hi,
//after the router B restore, did you see the BGP prefixes redistributed to the EIGRP topology on router B?
I did not see that. Any specific command?
//Are the router A and B receiving the BGP prefixes from the same router in a different AS? Or from different neighbors? Is there any BGP session between routers A and B?
Router A and B receiving the BGP prefixes from different routers with different AS (provider's router). But they advertise same routes. There is no BGP session between A and B. It's all EIGRP.
BR,
Milan
02-24-2009 07:48 AM
Hi,
command to check EIGRP:
show ip eigrp topology net mask
See http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094613.shtml#rdc
To understand completely:
Are there any other routers involved in EIGRP?
At the time of trouble:
Your internal subnets were not advertised via BGP from router B? (I.e., all traffis from the provider was still sent to A.)
Or the prefixes received from the provider were not redistributed to EIGRP on router B? (I.e., all traffic from your sites was sent to the providers via A.)
Or both?
Generally, mutual redistribution between two routing protocols is not recommended.
See http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009487e.shtml
e.g.
IMHO, you should make sure only correct subnets being redistributed, see
http://www.cisco.com/en/US/docs/ios/11_1/np1/configuration/guide/4ciprout.html#wp6060
as an example.
It's also possible that you are advertising the same (EIGRP learnt) subnets from both routers A and B (i.e., different originating AS from BGP point of view).
BR,
Milan
02-24-2009 10:30 AM
This is a case of mutual redistribution problem
So when you are redistributing EIGRP back to BGP you need to apply the filters as below
route-map eigrp2bgp permit 10
match ip address 1
set local-preference 90
set weight 0
access-list 1 permit
router A
router bgp 64808
redistribute eigrp 109 metric 1 route-map eigrp2bgp
HTH
Narayan
03-02-2009 01:52 PM
Thanks Guys. Looks like problem is resolved now. Even though EIGRP and BGP are being injected into each other, I am using prefix list not to accept certain routes.
Even if I use route-map to filter out certain routes, How can I achieve redundancy? RTR A and B are supposed to be acting as complete redundancy if one fails. So limiting certain routes means during failover certain routes are missing. Any thoughts?
03-02-2009 02:09 PM
Hi,
just guessing without knowing details:
IMHO, while RTA A and B are exchanging routing info via EIGRP, they shoud use the same AS number for BGP.
It's possible you might not need prefix filtering anymore then, as BGP would refuse prefixes originated from the same AS automatically.
BR,
Milan
03-02-2009 02:24 PM
Hi Milan.
EIGRP AS is the same but BGP AS is different.
So on two routers, Each BGP AS is different so they have prefix-list in place.
03-03-2009 08:10 AM
Hi,
yes, that's what I meant:
If you were using the same BGP AS number in both sites, the BGP process on router A would refuse the prefixes received via BGP from the provider but avertised by router B originally (and possibly redistributed from router B EIGRP) and vice versa.
That might prevent some routing loops in a case of router the other router fail/fix.
BR,
Milan
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