Possible Routing Loop?

barquerabarquera Member Posts: 21 ■□□□□□□□□□
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 B).
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 (points to the Router)
*Interface VLAN 1
ip address secondary
ip address

Switch B config:
ip default-gateway
ip route

As I was consoled into Switch A, I Telneted to Switch B and removed "ip route". 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?


  • EdTheLadEdTheLad Member Posts: 2,111 ■■■■□□□□□□
    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.
    Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
  • barquerabarquera Member Posts: 21 ■□□□□□□□□□
    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_lundejason_lunde Member Posts: 567
    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)
Sign In or Register to comment.