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New Member

3750 and dual connections

In the office today, we've been discussing how to improve the infrastructure in a 3 story building.

The idea is the use 3750 switches and on the floors with the largest use population, we would use multiple 3750 that are cascaded together.

The second and third floor would home back to the switch on the first floor.

The discussion then turned to the fail over ability of the 3750.

It was suggested that when the base unit in a stack would have an IOS failure, that the second unit in the stack would take over and the stack would not lose connectivity.

The alternate suggestion was to at least run a connection from the ground floor to the base 3750 in each stack on each of the other floors and a second connection to the last unit in each stack on each of the other floors.

The thinking was if the IOS died on the base switch, that the stack was dead.

The second connection to one of the other switches in the stack would provide reduncy need in case of a failure.

Any thoughts, comments or flames about either suggestion?


Re: 3750 and dual connections

I believe the resiliency is the most important issue. You can consider to use spanning tree or routing to provide the resiliency.

Do remember to have dual links from edge to core switch, or use ring design.

Just my 2 cents. Hope this helps.

New Member

Re: 3750 and dual connections

You could use the StackWise technology when cascading the 3750's and use EtherChannel back to the first floor for resiliency. With StackWise, if either switch fails, your stack continues to run, no matter which switch fails. Since using the StackWise technology makes the switches appear as one switch fabric, you don't have to worry about spanning-tree, etc. Onto the EtherChannel end, you could add a port from each switch in the stack to the Channel Group to protect from IOS/Switch failure.

New Member

Re: 3750 and dual connections

Keep in mind that there is a distance limitation on stacking 3750s. The cable is max 3 feet I believe. I might be off by a little. But if you are connecting floor to floor, then run 2 or more cables in an etherchannel and you can do cross-stack etherchannel for extra redundancy.

I'm running 4 Gbps cross-stack etherchannel uplink between my full stacks. I feel the need for more juice so I will try to get more sfp's to max it out at 8 Gbps, since my regular ports are all used.

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