Design question to expand LAN

[Andy White]

Hello,

We have a small office which is going to grow and I need to add some redundancy and also expand their switch setup.

They currently have 4 x 48 port 2960 access switches which trunk into a 3750 which all the SVIs are so it is quite simple.  Each access switch is a vlan so switch 1 is vlan 10 and switch 2 is vlan 20 etc.

We now want to add some more access switches and some redundancy so I thought that we should get another 3750, but how would I introduce this as I would need to keep the same gateways for the users PCs and also trunk the all access switches to both 3750s?

Woudl a normal setup use GLBP for the 2 3750s?

Thanks

[Leo Laohoo]

Cross-Stack EtherChannel on a Catalyst 3750 Switch Configuration Example

[Junaid Shah]

Yes Stack the core 3750 switches and make redundant trunk ports to access switches so if one goes down you have another trunk available, i am using eigrp routing in between core and access switches for that purpose and have routed interfaces instead of trunk ports with core switch. The access switches are trunked to each other though. And then you can use HSRP. Good luck!

[Andy White]

Thanks guys, so if they are stacked then and I trunk the access switches to the other 3750 then STP will take care of this (in simple terms)?

Junaid, can you explain your setup in more detail as this sounds like just what I want to try in my lab?  Sounds very interesting.

Thanks

[Leo Laohoo]

Thanks guys, so fi they are stacked then and I trunk the access switches tot he other 3750 then STP with take care of this (in simple terms)?

Enable Etherchannel and you can ignore STP.

[Andy White]

I see as it will be seen as 'one' switch?

Can you explain this as I'd like to understand how you can also use L3 in the core, maybe an example:

" am using eigrp routing in between core and access switches for that purpose and have routed interfaces instead of trunk ports with core switch. The access switches are trunked to each other though. And then you can use HSRP"

Thanks

[Shazli Savanghan]

Yeah you would see the stacked Switches as one..
So that way you can have etherchannelled trunk Ports going to your access switches from both the core switches that are stacked now..

In terms of L3 you can simply advertise SVI using the igp your using and in such a "collapsible core" model where the core is stacked I don't see the point in using FHRP like hsrp or glbp in this setup..... Unless of course you regard the two core switches as two different network elements without stacking...
And this would be a simple redundant design, without needing to worry too much of STP.


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