How to disassemble switch 3com 3c16476 - 3Com 3c16476 - Baseline 48pt 2 Gigabit

take it to the 4s garage, if you want to find out the problem by yourself,you first have some professional tool , there are some diagnostic that always can figure out the problem i can show you: www.xcardiag.com/

Search the following documents for 'Password Recovery':
http://support.3com.com/infodeli/tools/switches/4500/s3n03_01_00sp01_readme.pdf
http://support.3com.com/infodeli/tools/switches/4500/3Com_Switch_4500_Command_Reference_Guide.pdf
Both of these document discuss the password recovery process for this device.

If you also have a standard copper cable (or a second fibre cable) connecting the two switches (for resilience perhaps?), this issue is probably being caused by something called Spanning Tree. This is implemented on switches as a 'loop avoidance' system, and can look like you have described with one end 'ip' and the other end no lights.

On the Cisco switch, get to a telnet/ssh/console session, log in and enter show spanning-tree and press enter.

have a look to see if the fibre interface has a status (sts column) of BLK. If it has, then this is called 'blocking' and will remain like that until you remove the second link to the other switch.

Hope that this has helped!

not sure about the 3COM side, but on the Cisco side... go to the configure prompt, then the port that you need to trunk (int [interface name and number] and enter)

Once you are in the interface, use the following command:
switchport trunk encap dot1q
switchport mode trunk

Then make sure that the interface is not shut down, connect the switches together and (hopefully) the 3COM will negotiate to trunking... if not you will need to manually configure the 3com.

Hope that this helps!

I don't know anything about them, but here's a 444 page pdf on them. Hopefully it will help:

http://h20628.www2.hp.com/km-ext/kmcsdirect/emr_na-c02583472-1.pdf

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....

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.

page 22 of the 3com user guide for your switch talks about how to use the console cable and how to connect to your pc, I included the link below for your manual, if you don't have it:

http://support.3com.com/infodeli/tools/switches/baseline/3Com_Baseline-Switch-2916-2924_User-Guide.pdf

Do the ports work when the cables are connect?  I did some re-search and this seems to be an ongoing issue with 3com switches.  It should not effect the use of the switch