Possible Routing Loop?

barquera

Hi Everyone,

I just recently made some configuration changes at a remote site.
The site has 1 router, 1 6509 (switch A) and 1 6509 (switch .
Switch B acts as a Layer 2 switch and connects to Switch A via Gi1/1 (trunked port).
Switch A (does the local static routing) connects to the Router which routes to the Internet or Corporate via the Cloud.

Switch A config:
*ip route 0.0.0.0 0.0.0.0 10.13.5.1 (points to the Router)
*Interface VLAN 1
ip address 10.13.159.129 255.255.255.192 secondary
ip address 10.13.98.129 255.255.255.192

Switch B config:
ip default-gateway 10.13.159.129
ip route 0.0.0.0 0.0.0.0 10.13.159.129

As I was consoled into Switch A, I Telneted to Switch B and removed "ip route 0.0.0.0 0.0.0.0 10.13.159.129". I did this because it only needs to act as a layer 2 switch. Once I removed it I was kicked out of my console session on Switch A. I could not reconnect to Switch A via console for a few minutes.

I think when I remove the ip route from Switch B it somehow created a routing loop. Any thoughts?

EdTheLad

No routing loop, are you sure you were kicked out of the console? or did your telnet to SWB just hang? wrong section for this question anyway.

barquera

Hi Ed,

I was kicked out of my console session on Switch A but it's possible it did just hang.
If so it seemed like such a long time that I assumed that I was kicked out.
I just remember trying to reconnect via the console with no luck.
If I remember correctly, I think it took a few minutes again for me to console back into Switch A. Once consoled in, I could not Telnet to Switch B.
I then walked over to Switch B, consoled in and then put the "ip route" back in just so I could get things back to normal.


Please advise me on what section I need to post this type of question. I am somewhat new to this site as far as posting goes.

jason_lunde

If SW2 is just going to be a L2 switch make sure you have your mgmt svi set, default-gateway set, and turn off ip routing then. Then you should be safe to remove your default route and still be able to get to your box. Edit: (and make sure your STP topology is correct)