Fiber questions

mac_cnc

mac_cnc

2[H]4U
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Oct 14, 2000
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Ok quick overview:
Got a 3com superstack switch with addon fiber card (LC connector). We have an existing cisco unmanaged switch that is near death. So i want to connect the incoming fiber connection (from the warehouse) to the new switch. I bought the LC to SC cable to do it, but when i connect it to the patch panel for the fiber all goes well but i cannot ping any machines out in the warehouse and they lose all connectivity to the rest of the systems. The switch out in the warehouse is a cisco brand as well. Is the 3com not able to talk to the cisco? The 3com is managed and the cisco is not, does that make a difference?
Any help would be appreciated.

Thanks
 
Did you try flipping the fiber? Does the remote cisco switch see that interface as up/up?
 
Well i can flip the one connectors that go into the patch panel, which i have done but i will need to get into the ciscos box to see whats up tommorrow.
 
are you getting a link light when the fiber is plugged it? This sounds stupid but are both switches the same interface type? I have a strange feeling you are plugging a 1000 base X into a fast E fiber interface or something.
 
Check your trasmit and receive (make sure they are aligned) and you may wish to check your config on the the new Cisco..
 
are you using mode-conditioned fiber patch cables?

verify links on both sides.


again, verify whether (like said above) you aren't plugging a 100fx into a 1000base lx,

and if they are both 1000base make sure you aren't connecting SX to LX etc.
 
I deal with Cisco gear all day long.. I have never seen an unmanaged Cisco switch with fiber ports on it- MTRJ, GBIC slots, or SC ports.

Even the Cisco FastHubs have a console port for managment.

Regardless - I'll trust you have looked on the back of the switch for a "console" port.

If the switch is truly "dumb" then there must be a problem with the way your hooking up your fiber, the fiber type (MM vs SM), or the core size (50 micron/62.5 micron).

If the switch isn't dumb then maybe you need to look at the config and verify that it doesn't have VLANs config'd on it that are sending the traffic from the warehouse to nowhere.
 
Ok here is more info. The Cisco hubs are Fasthub 400 series. And i think i found out what was wrong the cisco fiber modules say 100fx and i think my 3com is 1000. How can I tell the micron size? Maybe my patch cable is not good enough. I just bought it though.
 
mac_cnc said:
Ok here is more info. The Cisco hubs are Fasthub 400 series. And i think i found out what was wrong the cisco fiber modules say 100fx and i think my 3com is 1000. How can I tell the micron size? Maybe my patch cable is not good enough. I just bought it though.
Click to expand...

It's either going to be 9 micron (Singlemode), 50um MM (higher bandwidth I.E. 10G), and more-commonly 62.5um MM.
 
mac_cnc said:
Ok here is more info. The Cisco hubs are Fasthub 400 series. And i think i found out what was wrong the cisco fiber modules say 100fx and i think my 3com is 1000. How can I tell the micron size? Maybe my patch cable is not good enough. I just bought it though.
Click to expand...


So if this is the case you are using a transceiver. Converts fiber to copper, etc. The Fasthub 400 series only have copper ports - so fiber isn't going directly into the hub without a transceiver.

You need the same on both ends - you can't mix 1000B SX/LX with 100B TX/FX. So if you have only a 10MB or 100MB transceiver on the Cisco hub side plugging into a 1000MB fiber port on the 3Com side - it isn't going to work. It needs to be 1000MB or 100MB on both sides and needs to be SX or LX on both sides -unless you have an SX to LX converter.

The Micron size of the fiber is "usually" printed on the side of the fiber patch cable something like 62.5/125 or 50/125.
 
thanks for the help edicted (and everyone else for that matter). What then would u suggest would be the "cheapest" route to take?
 
why dont you give us the model numbers of both the 3com and cisco switch? then we can tell you whats wrong and how to fix it instead of blindly geussing
 
cheapest thing would be to get a 100FX media converter for the HP, unless you want to replace the other Cisco too so that you have 1000SX on the other end... no way to hook 1000SX to 100FX
 
nick_sabatino said:
why dont you give us the model numbers of both the 3com and cisco switch? then we can tell you whats wrong and how to fix it instead of blindly geussing
Click to expand...

The 3COM is a superstack 3 3226 model with a fiber module installed and the cisco is a fasthub400.
 
mac_cnc said:
thanks for the help edicted (and everyone else for that matter). What then would u suggest would be the "cheapest" route to take?
Click to expand...


get a matching transceiver/media converter for the 3Com switch side
 
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