Switch connectivity/Will be loop ?

Unanswered Question
Jun 1st, 2010


we have two floors and three switchs.One switch(4500) is one floor and other two switch(3560) is other floor.Now two 3560 switch are connected with 4500 switch by two seperate cable.Now we want to connect another cable between  two 3560 swithch.Could you please tell me what i have to if i connect 3 cable between two 3560.Should i need any configuratin of all switchs.Is there any loop will be created if i connect 3 cable.Please have a look attachment for my drawing.It would be very much appreciated if you let me know your views.



I have this problem too.
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Calin Chiorean Wed, 06/02/2010 - 03:35

This is a very common topology and I can tell you that if you have there configure Spanning-tree (no matter which version) you will be loop free.

STP knows how to block a  port on the triangle to keep your topology free of loops. Of course this port will be unblocked in case there is an outage that affect other port, so there will be no interruption in your traffic.

For more information about STP I would recommend:


http://www.cisco.com/image/gif/paws/10556/spanning_tree1.swf   <- graphical example like your case



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