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Daniel Graham
Beginner

Cisco 3550 Stack

Not sure what I need to do this:

Two cisco 3550 switches

Goal is to have them "stacked" so they act as one switch.

When I create a vlan interface and unplug switch A, the vlan interface remains usable by switch B and vise-versa.

Do I need to use the Gigastack modules or can I use the existing GigE ports to do this?

Do I have to use clustering if I dont use gigastack modules?

Is my senario possible?

Thanks,

Dan-

7 REPLIES 7
Jon Marshall
VIP Community Legend

Dan

3550 switches don't support stacking in the 3750 sense. You can either cascade them by simply interconnecting them or you can cluster them, see this link for more details -

http://cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.2_44_se/configuration/guide/swclus.html

Jon

Leo Laohoo
VIP Community Legend

Hi Dan,

Q: Do I need to use the Gigastack modules or can I use the existing GigE ports to do this?

A: If you have GigaStacking GBIC, then use it. Please note that if you only have TWO switches to cluster, do NOT connect both stacking cables. Just connect one. Why? Because if you connect two stacking cables in an "X" or parallel fashion, the speed will drop from 1000mb/Full Duplex to 1000mb/HALF duplex.

Hope this helps.

Also, if you connect more than two switches with GigaStacking then you'll end up running 1000mb/HALF Duplex as well.

I dont currently have gigastack modules.

Can I use existing gig ports to acheive stacking?

Thanks for the info on the gigastack modules,

-Dan

Hi Dan.

As someone stated earlier, you cannot achieve stacking in the sense you do with Cat3750. You will, no matter what you do with Cat3550, end up with two switches, each with their own IP management address and own configuration.

You can then use clustering in order to simplify management a little, but it is still two switches.

As for interconnect GigaStack cables are the cheapest, but you can as well use RJ45 cables between ports as the conenction. If your Cat3550 have Gigabit ports, it will be the simplest way.

HTH

Looks like I'll be using HSRP.

Thanks,

dan-

Leo Laohoo
VIP Community Legend

Q: Can I use existing gig ports to acheive stacking?

A: Sure you can. Fiber and/or copper can be achieved, however, without using GigaStacking GBIC, you can use more ports if you use this alternative method.