Used 3Com switch - no IP?

[politby]

I have just purchased a used 3Com 4500 switch off eBay. It came without a console cable and also without any information on IP address, admin credentials or other configuration.

I have tested it and it appears to work fine but I would like to be able to access the admin interface.

Unfortunately I have discovered that the only way to factory reset the switch is to connect a console cable and run a terminal session. Of course the console cable is not just a standard serial cable or Cisco rollover cable. I have not managed to locate one.

I figured when I started it it would at least come up with an IP address or a DHCP request. I tried running Wireshark on a laptop connected to one of the ports on the switch, with nothing else connected, hoping for it to broadcast some ARP packets thereby revealing its IP address or at least the MAC address. But it does not appear to communicate anything at all. It does have a sticker on the bottom with a MAC address, but that address does not appear in the Wireshark capture.

I would have thought it would broadcast at least some packets when it boots. Could it have been configured in some sort of transparent mode?

Again if I connect some devices to it and plug it into my LAN, it does work. If it does have an IP address it is on a subnet I have no way of identifying.

I was wondering if there is anything I can do other than finding a console cable or making one myself.

Sent from my Nexus 4 using Tapatalk

 

[azazel1024]

Most switches and routers with an admin port are only accessible through the admin port.

Sooooo, more than likely, its console port access only or nothing. Likely there is no admin console available through the regular LAN ports.

I don't really know that to be true though, just a guess.

 

[fistv]

I don't remember any special cable, it was a straight serial, 8n1,9600, possible you *might* need a null modem, not sure, too many moons ago..
That said I use HP procurves and those switches come with an RJ45 to serial. If you could find it's IP address you could probably access it with telnet or it might have a web interface. If you connect your pc to the switch and use wireshark it will find it's ip even on a different subnet.

 

[abailey]

I believe the 3COM 4500 series switches can be managed by IP address either through CLI or a web interface. By default (like from the factory) they do not ship with a static IP, rather they look for a DHCP server on your network to assign them an IP address. If they get one then you can use that address to go into the configuration and change things (and assign a static IP if you want). Now if you don't have a DHCP server on your network you will need to get a console cable and connect into the switch that way. Then once in you can assign it an IP address and go from there.

 

[fistv]

I believe the 3COM 4500 series switches can be managed by IP address either through CLI or a web interface. By default (like from the factory) they do not ship with a static IP, rather they look for a DHCP server on your network to assign them an IP address. If they get one then you can use that address to go into the configuration and change things (and assign a static IP if you want). Now if you don't have a DHCP server on your network you will need to get a console cable and connect into the switch that way. Then once in you can assign it an IP address and go from there.

If it is configured for dhcp then plugging it into his router will get it one and the router should show it's IP, the switch should also have a mac label on the back or bottom and you can arp it provided it's on your subnet. If however it was given a static on a larger network say a class a in the 10 range you can find it with wireshark, you just need to set a static on the PC of pretty much any thing like 192.168.1.20 and connect a cable then run wireshark, it will show up in about 20 seconds even if it's on a 10.x.x.x subnet. The switch will be broadcasting. Now if the switch has it's dchp off and no static he will have to serial in. If he can then he can serial in, reboot and intruppt the startup, usally a 5 second window, and go into a menu driven configuration. Yea, I'm starting to remember those 3 coms. There is also a reset but it's inside the box.

 

[politby]

Well as I said in the original post I get nothing in Wireshark so I guess it is unconfigured. The manual says the default setting is with the DHCP client turned on so the previous owner likely changed that.
It came from an eBay listing of more than 40 so most likely a large deployment.

I am going to use it for security cameras so I'll just leave it unmanaged and put it on its own VLAN.

As for the console cable, inconclusive. Some say the standard Cisco cable will work, others say not.

Sent from my Nexus 4 using Tapatalk

 

[abailey]

Well as I said in the original post I get nothing in Wireshark so I guess it is unconfigured. The manual says the default setting is with the DHCP client turned on so the previous owner likely changed that.
It came from an eBay listing of more than 40 so most likely a large deployment.

I am going to use it for security cameras so I'll just leave it unmanaged and put it on its own VLAN.

As for the console cable, inconclusive. Some say the standard Cisco cable will work, others say not.

Sent from my Nexus 4 using Tapatalk

You can use it unmanaged but it is very possible that the previous owner set up some things like VLAN's, maybe LAG or QOS. It would be best to try to get into the management and see what's up. You could always try it as is and if something funny happens you will know you need to get into the configuration and see what's up.

 

[fistv]

http://www.mtmnet.com/04042967.htm

 

[politby]

Since it does not come up with a fixed IP or a DHCP request, I doubt it's got any subnets or VLANs configured. But after playing around with it a bit more today I discovered the SFP ports are acting strangely. Two of them are completely inop, I don't even get a link light. The other two come up with a link light when I connect them to my Microtik router but there is no actual traffic passing.

I definitely need to log into the console and do a factory reset. I have ordered a Cisco console cable locally, I can always cut it off and rewire it if the pinout isn't correct.

I am not located in the US so an actual 3Com cable is hard to find. I'll have to resort to eBay if I cannot make the Cisco cable work.

Sent from my Nexus 4 using Tapatalk

 

[politby]

There is also a reset but it's inside the box.

Do you have any more details on this? If I could just reset it to factory settings it would solve my problem.

Sent from my Nexus 4 using Tapatalk

 

[fistv]

Do you have any more details on this? If I could just reset it to factory settings it would solve my problem.

Sent from my Nexus 4 using Tapatalk

Been too long, one of the tech reps mentioned it in passing when we started supporting their NBX phone systems. HP bought them out so there is support on their web site. Once you get the cable you can push a firmware load which will set it back to factory defaults, you just need to make sure your hypertermianl sessions works. LI:3comcso PW:RIP 000 with a space.

 

[politby]

Okay. Well the console cable arrives on Monday and I have a Keyspan serial to USB already so I will know soon enough.

Sent from my Nexus 4 using Tapatalk

 

[politby]

I'm pleased to report the Cisco cable worked perfectly. I managed to reset it to factory settings. What a crummy user interface ..

Sent from my Nexus 4 using Tapatalk

 

[fistv]

I'm pleased to report the Cisco cable worked perfectly. I managed to reset it to factory settings. What a crummy user interface ..

Sent from my Nexus 4 using Tapatalk

LOL, you should have seen their NBX phone system interface...

 

[LoneWolf]

LOL, you should have seen their NBX phone system interface...

It got better with time, but I'll agree, it was a mess for quite awhile. Also gotta love the fact that if your NBX head unit died, licenses couldn't be transferred to a new one. Ouch.

There was a time when 3Com was the last word in NICs, switches, etc. That time is now over a decade past. I wouldn't buy a used 3Com switch just because support is extremely limited, and I wouldn't want to have to deal with HP for it.

 

[politby]

Well the switch is now installed in my attic and so far it runs perfectly. I do not expect to have to deal with the user interface at all, at least not until it dies from exposure.

 

[theonlyski]

If it is configured for dhcp then plugging it into his router will get it one and the router should show it's IP, the switch should also have a mac label on the back or bottom and you can arp it provided it's on your subnet..

I have had some success with creating a static ARP entry in my computer and using that IP to communicate with the device (since it's on the same subnet, the IP is irrelevant as the computer will send it to the MAC that I specified.

Kind of a pain in the butt way to do it, but in a pinch, it's helped me a few times.