NX-OS Redistribute Static Default Route into EIGRP

[Patrick Bixler]

I am in the process of spinning up a new Internet circuit in my Data Center and what to flip my routes to go out a secondary internet connection at our colo.  What I am attempting is to have 2 default routes in my routing table (one with a higher metric) so that when I kill the one in the Data Center, Internet traffic will flow out through the colo.  Currently I have the Nexus 7010 at the colo configured to not redistribute a static route using the following configuration.

ip prefix-list NoDefRoute seq 5 permit 0.0.0.0/0

route-map Static2EIGRP deny 10

match ip address prefix-list NoDefRoute

route-map Static2EIGRP permit 20

router eigrp CCHCS500

autonomous-system 500

eigrp event-logging

redistribute static route-map Static2EIGRP

I changed that configuration to this.  The issue is that I am not seeing this static route being learned on any other part of my network.

ip route 0.0.0.0/0 10.200.25.10 200

ip prefix-list static-default seq 50 0.0.0.0/0

route-map static-default permit 50

  match ip address prefix-list static-default

router eigrp CCHCS500

  no redistribute static route-map Static2EIGRP

  redistribute static route-map static-default

On the 7k I see this when doing a "show ip route eigrp-CCHCS500".  This shows both the learned default route (coming from the Data Center) and the static default route on this 7k at the colo.

c7kDR1# show ip route eigrp-CCHCS500
IP Route Table for VRF "default"
'*' denotes best ucast next-hop
'**' denotes best mcast next-hop
'[x/y]' denotes [preference/metric]
'%<string>' in via output denotes VRF <string>

0.0.0.0/0, ubest/mbest: 1/0
    *via 10.20.30.225, Vlan960, [170/259328], 5w6d, eigrp-CCHCS500, external
     via 10.200.25.10, [200/0], 00:36:37, static

Nowhere else am I seeing 2 static default routes.  I have looked at various blogs and documentation and while I find a lot about redistributing static routes, I don't see much about redistributing default static routes, if that makes any difference.

[Jon Marshall]

For a route to be redistributed it must be in the IP routing table and you are receiving a default via EIGRP with an AD of 170 so your locally configured default with an AD of 200 won't be in the routing table hence it will not be redistributed into EIGRP.

Note I am not that familiar with Nexus but I believe the same rules apply although I was surprised to see both routes in the "sh ip route eigrp-CCHCS500" so perhaps I am wrong.

Jon

[Jon Marshall]

Should have said that your setup should still work because if the current default route is not received on your switch then the locally configured default route will be placed into the IP routing table and then redistributed into EIGRP and advertised to the rest of the network.

You just can't advertise them both if they have different ADs.

Jon

[Patrick Bixler]

I know that IOS and NX-OS are 2 completely different animals.  With IOS, I would be able to have 2 routers with different ADs advertising default routes and see both of those routes elsewhere on my network.  For example, on an intermediate router I would see a default route with an AD of 90 and a second one with the AD of 200. 

I was hoping to do the same with NX-OS.  I do have TAC support, but this change goes into effect at 4AM tomorrow morning, so I am looking for the quickest answer anywhere.

[Jon Marshall]

AD is not passed in routing updates so on an intermediate router in IOS you would not see different ADs.

You could see both default routes with the same AD although whether you would or not depends on a few things.

I do not believe the rules are different for Nexus and as I say I think what you are trying to do will work but you cannot advertise them both out at the same time if your Nexus is receiving a default with a lower AD than the one you configured locally.

It will only advertise the local one out if it no longer receives the other one via EIGRP.

Jon