Connect 2 3750 Stacks

[CobbyJ]

Hello.

We want to connect 2 3750 stacks using fibre or ethernet cables because that are in different rooms but we also need our first stack to be a master with ip routes in and our secondary stack to also have the ip routes as redundancy and only to become into effect if needed.

Or does it not matter if we just have the ip routes on both and just connect the switches togeather via ethernet?

we are basically looking to make a redundant core network so if our first stack goes down our second stack will take over.

Kind Regards,

Chris

[Reza Sharifi]

Hi,

You would need IP routing enabled on both stacks if they are being used as core switches.  This way if one stack fails the other stack can perform the routing.

HTH

[CobbyJ]

OK, i was just worried this would cause some kind of loop or issue.

Is there any guide or anything that can provide more details on what im trying to do?

I have seen some ways to set priority in switches but i think thats just for the switch connectors and not for ethernet or fibre connections.

[Deepak Kumar]

Sorry for misunderstanding the question.

[paul driver]

Hello

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@Deepak Kumar wrote:

Hi,

No there will no loop in the stack because there will be only one Management and Control panel for a stack switch(s). 

Here is a guide for stack configuration: https://blog.router-switch.com/2013/04/cisco-3750-stacking-configuration/

We are recommending to configure Priority and switch number on each chassis in a stack. The master switch in a stack is the one with the highest priority. To make sure that this new switch does not become the master, make its priority lower than the master switch. You can run show switch on the master switch to see what the current priorities of the other switches in the stack are. Set the priority like this:

(config)#switch 1 priority <priority>

Avoid configuring uplinks on Master switch due to some reasons as Uplink will fail if stack master went down. You have to make changes on stack master switch and it will replicate to all switches means there will be one stack management panel. 

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@Deepak Kumar You are incorrect here the two stacks wont be in the same stackwise configuration they will be two separate cores because they will connected via fibre links and not stack wise cabling and the 3750's dont support virtual-stacking.so as a result they will just act like two physical core switches interconnected most probably by using a FHRP like HRSP.

[Deepak Kumar]

Hi @paul driver 

Thanks for the update. I am sorry for missing the original question and product information as shared by original questioner. I am going to remove my answer. Thanks again.

[Reza Sharifi]

You should not have a loop if you are using both stacks in later-3 mode with IP routing enabled. So, you can use one stack to be the primary for all your vlans using HSRP or VRRP and the stack would be the backup stack. In this scenario, you just have to make sure that all access switches connect to both stacks. Do you have a topology you can share?

HTH

[CobbyJ]

This would be the end result but i just need more information on the configuration.

I would need to configure HSRP priority and configure it but for example would connections direct to the secondary stacked 3750 still work as a functionaly switch and would i still need to add in extra configurations like IP Routes to both stacks or would the secondary stack read from the primary?

[Reza Sharifi]

You would need the same config on both primary and backup core stacks. The only different between them would the HSRP/VRRP priority to make the master preferable.

HTH