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Routing with EIGRP / BGP

dtran
Level 6
Level 6

Hi everyone,

I have a routing scenario, hope someone can give me some insights.

I just brought up a new office using a pair of Nexus 7706 connecting to my data center over 2 L3 10Gig links (see diagram). I am also using a pair of Palo Alto 5250's running as my firewall and default gateway handling local routing. All my access switches are connected to the Nexus 7706 via vPC. The Nexus 7706 and Palo Alto are exchanging routes via iBGP. I am doing EIGRP/BGP mutual route redistribution at the Nexus 7706.

 

Everything is working normally from the users perspective. I see traffic leaving the new office is working fine, the issue/concern that I am seeing is traffic entering the new office from the data center. I am seeing when traffic leaving the data center hitting the Nexus N7010-1 it gets routed over the Nexus N7010-2 to get over to new office where it should get routed across the directly connected 10Gig link. Any ideas why that happens ?

 

Thanks in advance everyone !!!

DannyHQ Campus - Data Center WAN Layout v1.0.png

7 Replies 7

Alex Pfeil
Level 7
Level 7

If you look at the EIGRP feasible and reported distances, the cost is probably being preferred over the 7010. You need to verify you have the same routes in the EIGRP topology table. You might be able to resolve this with a summary route from the 7010 so that you prefer the longer match. However, there are many different ways to accomplish this.

 

please mark helpful posts.

 

Hello

Can you post from 7010's
sh ip route eigrp

sh ip eigrp topology all-links 


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

Hello Paul and Alex, thank you very much !! I appreciate your responses !!

 

Attached is the "show ip route eigrp" and the "show ip eigrp topology all-links" command outputs from N7010-1 and N7010-2

172.16.216.0/23 is one of the networks at the new campus. 

Hi Danny!

 

Thanks for sharing those outputs! I focused on the 172.16.216.0/23 network you mentioned and found the following:

 

+ 7010-1 routing & EIGRP table:

`show ip route`
<snip> 172.16.216.0/23, ubest/mbest: 2/0 *via 172.16.1.2, Vlan301, [170/51712], 8w1d, eigrp-1, external, tag 100 *via 172.16.1.6, Vlan302, [170/51712], 8w1d, eigrp-1, external, tag 100
`show ip eigrp topology all-links`
<snip> P 172.16.216.0/23, 2 successors, FD is 51712, tag is 100, serno 212703 via 172.16.1.2 (51712/51456), Vlan301 via 172.16.1.6 (51712/51456), Vlan302 via 172.16.1.26 (51968/51712), Ethernet2/6 via 172.16.1.14 (51968/51712), Ethernet2/7 via 172.16.1.22 (51968/51712), Ethernet2/5 via 172.16.1.38 (51968/51712), Ethernet2/30 via 172.16.1.46 (51968/51712), Ethernet2/38 + 7010-2 routing & EIGRP table:
`show ip route`
<snip> 172.16.216.0/23, ubest/mbest: 1/0 *via 172.16.5.62, Eth3/4, [170/51456], 8w1d, eigrp-1, external, tag 100
`show ip eigrp topology all-links` P 172.16.216.0/23, 1 successors, FD is 51456, tag is 100, serno 213388 via 172.16.5.62 (51456/51200), Ethernet3/4

Based upon this output, we can see that N7010-1 has two routes in the routing table forwarding to 172.16.1.2 of VLAN301 and 172.16.1.6 of VLAN302, which (based upon the provided topology) appears to be N7010-2. However, the EIGRP topology table of N7010-1 shows a number of other higher-cost routes via a variety of IPs off of Eth2/5, Eth2/6, Eth2/7, Eth2/30, and Eth2/38. The provided topology doesn't depict any physical interfaces - would you happen to know what interfaces the 7010s and 7706s are using to connect through the 10G L3 EIGRP link depicted in the topology?

 

I would also like to check the EIGRP configuration across all routers, as well as the current EIGRP neighborships. Please provide the output from the following commands executed on both N7010s:

show run eigrp
show ip eigrp neighbors

Please provide the output from the following commands executed on both 7706s:

show run eigrp
show ip eigrp neighbors
show ip route 172.16.216.0/23

Please include the configuration of any route-maps used to perform redistribution between iBGP and EIGRP on your 7706s.

 

Thank you!

 

-Chris

Hello Christopher and thanks for responding to my post !!!

I went ahead applied a distribute-list on the L3 Interface VLAN301 and VLAN302 on the HQ Nexus 7706's to basically NOT advertise local routes to each other. I applied the distribute-list then shut / no shut one of the 10G links to allow EIGRP to re-converge and that seems to resolve the issue. I am seeing traffic flowing correctly now.

 

interface Vlan301

  description L3 Routed Traffic
  no shutdown
  no ip redirects
  ip address 172.16.1.53/30
  no ipv6 redirects
  ip router eigrp 1
  ip distribute-list eigrp 1 prefix-list FilerLocalRoutes in

interface Vlan302
  description L3 Routed Traffic
  no shutdown
  no ip redirects
  ip address 172.16.1.57/30
  no ipv6 redirects
  ip router eigrp 1
  ip distribute-list eigrp 1 prefix-list FilerLocalRoutes in

 

Thanks !!

Danny

Hi Danny,

 

I'm glad to hear that you were able to sort this issue out! Thank you for letting us know how you solved the issue - the solution definitely makes sense.

 

Thanks again, and let us know if you encounter other related issues!

 

-Chris

Thanks Chris !!! I very much appreciate all your help !!!

 

Danny