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This might just be the dumbest question you'll ever read, but I digress.

Say I have two 100Mbps Ethernet switches with 2 computers on each, connected together by a single cable. This way, the two PCs on each switch share the 100Mbps bandwidth with the others. If I added another cable between the 2 switches, would there be 200Mbps throughput available between the switches?

Or am I completely off my rocker?

Thanks for the help.

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up vote 11 down vote accepted

If you added another cable between unmanaged switches, it would create a network loop and destroy your bandwidth until you disconnect one of the cables.

Putting two cables between two manageable switches, and you've got options:

  1. Do nothing, and Spanning Tree Protocol will detect the loop and disable one of the links, putting you back into the single-link 100mbps case.
  2. Set up link aggregation, and get something slightly less (due to overhead) than 200mbps of bandwidth between the two switches.
  3. Set up failover, and get 100mbps that doesn't fail just because one link fails.
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Probably a good time to review the difference between managed and unmanaged switches. – Phil Hollenback Feb 25 '11 at 8:26
+1, although the fact that a switch is a managed switch doesn't mean that STP is enabled by default. I've got a managed switch that doesn't even have STP. – joeqwerty Feb 25 '11 at 10:57
Thanks a lot! This is definitely good to know. – user72153 Feb 25 '11 at 21:54

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