How I can Stack two 4500G switches

Originally we had a one 3Com 4500G 48 port switch on the network, the we added a 2nd 4500G port POE switch. We used the port 25 in each switch as uplink. However when we power up the unit we lost the comunication with some windows and Apple servers, and some Minotal network printers (Apple Talk was disable without user interventiono the printers) We pull out the switch , everithing works.
How we can stack those two switches together to avoid any conflict on the network.

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Sounds  a little confusing.

But, with the support for a 10G link, aren't you getting close to stack speed?  My stacks connect at 10G or 24G.  I bought the 24G stack cable...well, because it was listed with the proper part number.

As far as true backplane stacking...don't know if that still exists without bandwidth limitations.  When switch speeds maxed out at 10/100, having a stack cable or using 2x1Gbps LAG seemed more than adequate.
This manual:
See chapter 4 for how to stack the switches.
If you are patching from the front, make sure that you use only one cable.  A second cable would create multiple patch, which would confuse the switches and break connectivity.

You can patch with multiple cables on the front, but you have to create Link Aggregate Groups (LAG) on each switch.  For more bandwidth, 3Com offers three ways to link.  Here's one:

10Gigabit uplink module, plugs into the rear of each switch.

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I see reference materials at

Notably, these switches have layer 3 capabilities.
I would suggest checking what IP addresses these switches are assigned, before you consider connecting them together with a cross-over cable.

I.E.  Make sure they have distinct ip addresses for management.
Make sure the new switch does not have any ip that conflicts with any other device on your LANs.

Keeping in mind that a switch with layer 3 capabilities may have many different ips (on different VLANs)

It is best if the new switch started with a blank factory  configuration, and you had set it up specifically to connect to the other.

VLANs and all.   With  802.1Q   tagging on your inter-switch link
(that is, if you use VLANs in your environment).

HolguerAuthor Commented:
The IP addresses on the switchs are different e.g ( and 122). We do not use VLANs in our infrastructure; however, we like stack both units as one to expand our capabilities up to 96 ports.
Any ideas how to do it?
Did you read the documentation provided?
HolguerAuthor Commented:
I founf from 3Com that the 4500G 48 port POE switch is standalone switch, is not stackable. however you can cluster them  up to 32 units for managment purposes.  (Misleading informoation in part o 3Com due to th swich is listed under in the family of stakable switches)
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