×

Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.

Looping Catalyst switches

Unanswered Question
Jul 11th, 2003
User Badges:

The current situation is this:

3 Switches ( 1,2 and 3) with 2 gigabit cards each ( a and b). 2A connected to 1B, 2B connected to 3A. The world is happy, traffic is flowing. We installed another switch ( Gigabit 4A and 4B)and for redundancy connected 4A to 3B and 4B to 1A so if one of the cables failed there would still be a path. As I found out, this doesn't work. I am thinking spanningtree will rectify this but am not sure

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Bobby Thekkekandam Fri, 07/11/2003 - 11:07
User Badges:
  • Cisco Employee,

Yes,


by introducing the 4th switch, you are creating a physical loop. If you have spanning tree protocol disabled, then your switches will not forward traffic properly in this scenario.


Make sure spanning tree protocol is enabled, and it will logically block one of the ports so that traffic is not looped.

Actions

This Discussion