EIGRP setting Default Route though routing

[Adam Coombs]

I have 3750e and 6513 that is using EIGRP routing and setting default route to another switch, instead of firewall

How do i find out where these two switches are getting the EIGRP route from

Here is what is on both switches

D*EX 0.0.0.0/0 [170/3072] via 172.16.0.X, 7w0d, Vlan2?

Here from 3750e switch

sh ip eigrp neighbors

EIGRP-IPv4 Neighbors for AS()

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq

                                            (sec)         (ms)       Cnt Num

2   172.16.0.A             Vl2?             11 08:49:34    7   200  0  4138

1   172.16.0.B             Vl2?              12 08:49:34    2   200  0  5036

0   172.16.0.C             Vl2?              12 1w4d        5   200  0  409

4   172.16.0.D             Vl2?              14 8w4d        9   200  0  5311

5   172.16.0.X            Vl2?              10 8w4d        8   200  0  2181

3   172.16.0.E             Vl2?              11 8w4d       10   200  0  163686

Here from 6513 switch

sh ip eigrp neighbors

IP-EIGRP neighbors for process 500

H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq

                                            (sec)         (ms)       Cnt Num

3   172.16.0.A             Vl2?              12 10:58:02    4   200  0  4138

2   172.16.0.B             Vl2?              11 10:58:02    2   200  0  5036

0   172.16.0.C            Vl2?              14 1w4d        2   200  0  391

4   172.16.0.D             Vl2?              11 8w4d        9   200  0  5302

5   172.16.0.X             Vl2?              13 8w4d        6   200  0  2172

1   172.16.0.F             Vl2?              12 8w4d        6   200  0  2051

[Jan Hrnko · Accepted solution]

Hi Adam,

What about:

Router#sh ip eigrp topology 0.0.0.0

(Switch)

There should be Originating router field, that marks the router which injected that route into the EIGRP.

Example topology:

R1-s1/0----------s1/0-R2-s1/1---------s1/1-R3

R1 s1/0 12.0.0.1

R2 s1/0 12.0.0.2

R2 s1/1 23.0.0.2

R3 s1/1 23.0.0.3

R3 is injecting default route.

R1's output:

R1#sh ip eigrp topology 0.0.0.0
IP-EIGRP (AS 1): Topology entry for 0.0.0.0/0
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2809856
  Routing Descriptor Blocks:
  12.0.0.2 (Serial1/0), from 12.0.0.2, Send flag is 0x0
      Composite metric is (2809856/2297856), Route is External
      Vector metric:
        Minimum bandwidth is 1544 Kbit
        Total delay is 45000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2
      External data:
        Originating router is 23.0.0.3
        AS number of route is 0
        External protocol is Static, external metric is 0
        Administrator tag is 0 (0x00000000)
        Exterior flag is set

You should be able to identify the delinquent that way.

Best regards,

Jan

[Adam Coombs]

Wow I wish I would have check this earlier.

Ok, from that command I found out where that route is coming from thank you very much.

Now how do I change it from that 3750e switch to 6513

What should i look for in the switch that is sending out default route?

[Jan Hrnko]

Hi Adam,

You're most welcome.

Now how do I change it from that 3750e switch to 6513 
What should i look for in the switch that is sending out default route? 

Most probably, you have static default route configured (ip route 0.0.0.0 0.0.0.0 ip_address) and you are injecting it into EIGRP through redistribute static command under router eigrp AS_number.

So if I got this correctly - you want to change default route that is pointing towards 3750e to ip of 6513, right?

So look for statement like that (ip route 0.0.0.0 0.0.0.0 ip_address_of 3750e) in running config, put no in front of it

Switch(config)#no ip route 0.0.0.0 0.0.0.0 ip_address_of_3750e

and afterwards do something like this:

Switch(config)#ip route 0.0.0.0 0.0.0.0 ip_address_of_6513

But bear in mind, that the Router will have to perform recursive lookup for the IP address provided in the ip route statement - in other words, it won't work properly if the device does not know how to get to (does not have any route for) that specific IP address.

Best regards,

Jan

[Adam Coombs]

Well, you are correct I was trying to change from one ip address 3750e to 6513 default route though eirgp. 

But the senior engineer made the change last before i could do more research.

It was just weird that eigrp routing was sending out the default route to a location we dont used much then from that route it would go to the 6513.

So if i explain this better

traceroute 8.8.8.8

this would send the packet to default route then from that switch it would send it to it's default route which is 6513 then to internet and back

3750e --> 3750e --> 6513 --> internet instead of 3750e --> 6513

Thank you very much for all your help