Nexus or otherwise distribute-list with a route-map

[Garry Cross]

I have an objective to modify the admin distance of certain routes under the eigrp routing process.

I have tried this with 3725 IOS running under dynamips.

I have attempted this on a N9K running NXOS 6.1. The real target for this config will be for Nexus so let's focus on that.

First the route I am targeting.

10.161.6.0/24, ubest/mbest: 1/0
    *via 207.130.143.225, Vlan504, [90/3584], 1w4d, eigrp-500, internal

IP-EIGRP (AS 500): Topology entry for 10.161.6.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 3584
  Routing Descriptor Blocks:
  207.130.143.225 (Vlan504), from 207.130.143.225, Send flag is 0x0
      Composite metric is (3584/3328), Route is Internal
      Vector metric:
        Minimum bandwidth is 1000000 Kbit
        Total delay is 40 microseconds
        Reliability is 255/255
        Load is 5/255
        Minimum MTU is 1500
        Hop count is 3
        Internal tag is 0

There is no change after applying the below config. Thx.

ip prefix-list pl-test permit 10.161.6.0/24

route-map test permit 10

match ip address prefix-list pl-test

set distance 170 15

route-map test permit 20

interface vlan 504

 ip distribute-list eigrp 500 route-map test in

[Paul Chapman]

Hi Garry -

I've found that the "set distance" command does not always work.  I recommend using the "set metric" command instead.  In IOS and N7K you can use "+" or "-" to add or subtract to metric values.  As usual with EIGRP, delay is the recommended metric to change.

route-map test permit 10
 match ip address prefix-list pl-test
 set metric 1000000 -1000 255 1 1500

The N9K command reference is a little unclear as to whether or not it can be used on anything but bandwidth.

N7K Command Reference

N9K Command Reference

Good Luck!

PSC

[Garry Cross]

Thanks but  I need the route to be better than an EBgp route across a parallel link. Customer has this working using distance command on IOS switches. Migrating their DC core to Nexus. Distance cmd on Nexus affects entire process only. The customer wants certain traffic not to traverse the first link. There are other ways to accomplish this. Just exploring the ways it can be done. Ì haven't tried to modify the metric on nexus but on an older 3750 setting the metric as you indicate did not work so I did not try that. I also did not try to use - on the delay. Just a fixed value that was different than the default. It won't help my situation anyway.

[Paul Chapman]

Hi Garry -

You didn't mention eBGP in your initial post.  It sounds like you have the same route coming from 2 directions to the same router: one from eBGP and one from EIGRP.  In this case I would usually recommend that you create a BGP backdoor so that the IGP is preferred.

Well, unfortunately some quick research shows that BGP backdoor may not be supported in NX-OS.  Take a look at Carole Reece's article here, and let me know if it is helpful.

PSC

[Garry Cross]

Thanks for that. Thinking maybe to change the AD of BGP so that all of the EIGRP routes will be preferred. Currently the eBGP routes run on one link, and certain networks get a lower AD. New design could be that I use EIGRP metrics to push certain networks to the desired link. This would include the eBGP peer connection. There isn't any redistribution eBGP to EIGRP or vice versa so routes coming in from the WAN would follow the peer link.

[Garry Cross]

A little more testing and in the N9K version 6.1(1) you can set the bandwidth and the delay. The following is the relevant config. +/- is not an option though.

Here is the config.

ip prefix-list pl-test seq 5 permit 10.161.6.0/24
!
route-map test permit 10
 match ip address prefix-list pl-test
 set metric 100000 80 255 1 1500
route-map test permit 20
!
int vlan 505
  ip distribute-list eigrp 500 route-map test in

Here is the topology before and after

IP-EIGRP (AS 500): Topology entry for 10.161.6.0/24
 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 4096
 Routing Descriptor Blocks:
 207.130.143.234 (Vlan505), from 207.130.143.234, Send flag is 0x0
 Composite metric is (4096/3840), Route is Internal
 Vector metric:
 Minimum bandwidth is 1000000 Kbit
 Total delay is 60 microseconds
 Reliability is 255/255
 Load is 5/255
 Minimum MTU is 1500
 Hop count is 5
 Internal tag is 0

IP-EIGRP (AS 500): Topology entry for 10.161.6.0/24
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 4096
  Routing Descriptor Blocks:
  207.130.143.234 (Vlan505), from 207.130.143.234, Send flag is 0x0
      Composite metric is (46080/3840), Route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 800 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 5
        Internal tag is 0