Switch Connectivity

[DAvelarNIC]

Hi Cisco experts!

I have a quick question I am sure you can answer for me. I have IDF's setup for clients that I have questioned how they are physically connected. Connection to the MDF is ok as they are using their 10GB ports over fiber. The question I have is if there are multiple switches in the IDF should they be connected to each other using their 10GB ports from A to B to C and then also connecting A to C on switch ports? I think this is could cause a loop but wanted expert opinions.

Thanks                  

[Reza Sharifi · Accepted solution]

Hi,

Yes, when you have multiple MDF switches, you connect them together to provide redundancy for the network.  Of course if you are connecting layer-2 switches together, you need to run stp or use some other technology like stacking to make the entire MDF look like one switch.  There is also VSS for the 6500 which provide the same benefit as the stacking on the 3750 series.  This way, your don't have to use STP.

HTH

[Leo Laohoo]

Depends on your budget and the amount of fibre optic runs you have from your IDF to your MDF/Core switch.

I have worked in the past where we have a stack of 3750E switches with two links (for redundancy) back to the core switch.

My current work has each switch go back to the core using a 1:1 ratio between the access switch and fibre.

[DAvelarNIC]

Thanks for the replies! I believe I may not be asking the question correctly. The connection from the IDF switches back to the MDF is fine. Its a single fiber run using switch A's 10GB port or port TE0/1. Port TE0/2 goes to switch B.

Switch B port TE0/1 goes to Switch A and its port TE0/2 goes to Switch C.

Switch C port TE0/1 goes to Switch B and port TE0/2 goes back to switch A. Additionally on Switch C there is a copper uplink to Switch A on port gi0/24.

I am wondering if this could be causing a loop because I do see the macflap issue reported only on this IDF.

[Reza Sharifi]

Correct, if the connection between all these switches is layer-2, than you need to run some sort of STP to prevent loop.

HTH