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Stack question

Andy White
Level 3
Level 3

Hi,

I successfully stacked 2 3750's and they have been fine for a few months.  I used a stack cable from stack port 1 to stack port 1 on the other switch, but today I was told that is wrong it should go from stack port 1 on one of the swithces and connect to stack port 2 on the other, is that right?

1 Accepted Solution

Accepted Solutions

Hi

Yes, just refer back to that document I posted earlier... as long as you are creating a loop, it's fine.

Regards

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

View solution in original post

15 Replies 15

Aaron Harrison
VIP Alumni
VIP Alumni

Hi

It doesn't matter - as long as you have both the ports connected up:

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/hardware/quick/guide/3750GSG3.html#wp53466

It's more common to cable 1 to 2, then 1 on the bottom to 2 on the top for the resilient connection. In a two switch stack, just connect them all up to make a loop.

Regards

Aaron

Please rate helpful posts..

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

I see, so for 2 switch I'm fine, but if I add a third I'm not?

When you buy a 3750, you get  a 50cm stack cable with it.

So you have two switches now, do you have two cables connecting them?

I.e. port 1 to port 1, port 2 to port 2?

If so, you just disconnect the port2 cable, and work the third switch into the pattern.

It's easier to get your head around if you cable Sw1 Port2 --> Sw2 Port1, Sw2 Port2 --> Sw3 Port1, then Sw3 Port2 --> Sw1 Port1, but other configurations work fine.

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

Worse one cable > port one to port one

I see..

Then you can add a third switch by connecting it to any available port.

What you don't have is resilience... and half of your bandwidth.

You should pick up another cable from somewhere and put it in.

Regards

Aaron

Please rate helpful posts..

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

Thanks I will pick up another stack cable, so port 1 will go into port 1 and port 2 into port 2, would that be ok?  Then there would be no downtime as I don't have to unplug the current stack cable.

Hi

Yes, that's it.

Regards

Aaron

Please rate helpful posts!

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

Can I just add the addition stack cables live?

Hi

Sure - just make sure you don't disturb the existing cable. They're not always screwed in as well as they should be.

Regards

Aaron

Please rate helpful posts..

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

Thanks for your quick reply, there maybe a chance i need to add a 3 switch later in the year.  At the moment I will just have 2 switches with stack port 1 & 2 into the same ports on switch 2, I guess I will have to mix things up in a 3 switch scenario?

Thanks

Hi

Yes, just refer back to that document I posted earlier... as long as you are creating a loop, it's fine.

Regards

Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

I am having a similar problem. I have two stacked 3750G 48 port switches working well. I tried to add a 3rd 3750 G 24 port and it wouldn't work at all. The error I originally made was I configured an IP for VLAN1 on the 3rd switch which confused the master no end !!. Removed that and did a reload, still not working. They are running slightly different IOS versions the 48 porters are 12.2 (25) Se3 and the 24 port is 12.2 (35) Se5, can anyone suggest a solution please ?, this is a high level project and I need to get it working. All help appreciated thanks.

I

Hi

1) Switch the new switch off

2) Connect it to the stack

3) Power it up

4) Connect to the existing switches in the stack by telnet or console into one of the original switches, and do a 'show switch'. You should see it listed with it's current status. Let us know what the status is and post back the output.

Also post back the 'show version' output.

Likely it hasn't copied the software over - when adding to the stack they all need to be on the same version.

You can use 'archive copy-sw' to force the software on to the new switch.

Regards

Aaron

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Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

How have you got your stack cables, how have you provisioned them, they should be the same ios.

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