I want to know the default ip address of 3com superstack 3 switch 4500 model and the default username and password of the device

1. Using a Null-Modem Cable , hook up the Console port of the switch to an available COM port on a computer (cable must be able to provide serial port communication between 2 computers).
2. Set up a Hyperterminal session to that COM port (e.g.: com1), with the port settings at 9600/8/N/1/N (. When the screen comes up blank with a blinking cursor, hit [enter] once or twice to bring up a login prompt.
3. Alternative to 1 and 2 above, if there is a known assigned TCP/IP address for the switch, one can telnet to that address, hit [enter] once or twice to get the login prompt.
4. Default logins to try are admin/(no password) or security/security. One of those 2 should bring up the management menu.
5. To reset factory defaults, type SYSTEM[enter] then type INITIALIZE[enter]. This will reset everything that has been set up on the switch, with the exception of the TCP/IP address, if there is one. All other previous configurations will need to be re-entered.
6. You can type in username "3comcso" and password "RIP000". It will ask you to reinitialize the switch. This will reset all settings including passwords.

Connect some text-based terminal emulator such as Hyperterm, telnet,VT100, etc to the serial port. Configure the emilator
to19200 Baud 8 plus none.

Switch the 4924 on and login using the user "recover" (without quotes) and password "recover" (also without quotes.

The switch will go into recovery mode. It will display a count-down starting at 30 seconds. If you power thye switch off before the count is up, the default password for the main administration account "admin" will be cleared.

After a few seconds, power the switch on and set a new admin password.

After loigging in again, take the option "GettingStarted". Configure the ip settings (best to use a static address) and eventually you will get to the "Initialize" option. Enter yes, and after reboot it will be at factory except for its ip address.

check the manual of your device if that's is the IP address assigned by default;if you are out of manual.try 192.168.1.1;it's usually assigned by the manufacturer.

otherwise if you know all the IP address of your network devices then download Cisco Network Magic Pro from purenetwork Company.
 the url is http://www.purenetworks.com/ 

click the try it button and download it.

It will  automatically scan your network and display all the PCs & network devices.pin point the one Ip address that you have miss out.it should be the IP address of that particular switch.try Default username & password  as admin  for both.

Let me know if it's helpcul to you

I haven't worked with these switches but generally settings such as ip address and factory defaults can be set through the Console Interface (CLI). You will need a null-modem cable to access this and a terminal client (Windows Hyperterminal works).

Hope that helps

try 192.162.1.254

i can't set ip address over 4 vlans. the 3com switch 4500 always give error message "there's not enough routing resources available".please help....

You Could check to see if it has a passowrd and username as 3com or user as username or password thats wat mine is and i forget my pass

The primary connection method for those switches would be serial connection. In the box there should have been a DB9 serial to RJ45 cable. Hyperterminal default settings would allow you to connect.