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Make Fiber Ports Live on Catalyst 3750?

Hello All,

Have 2 Catalyst 3750's connected via fiber to the cisco gbics converts. Both gbic's are plugged into Slot 1 of 4 on the switches. Everything is physically hooked up correctly. My question is what command do I type to make the fiber ports active? I know the fiber led should go orange for 30 sec then green when you plug the fiber cable in the gbic but it's not working because I've got to make that port or interface active first right? Any help would be appreciated. Thanks in advanced!

7 REPLIES

Re: Make Fiber Ports Live on Catalyst 3750?

All ports should be enabled by default. You can try a no shut additionally. Make sure the fiber tx and rx are connected (cross over) if connecting to another switch..Only then you will get alink light (green).

New Member

Re: Make Fiber Ports Live on Catalyst 3750?

The switches are linked via a fiber patch panel. The corner cabling system by landscape. We use the ST to LC MM fibers to the gbic. My WAN guy pcanywhere'd into the laptop then consoled into the switch and was typing some commands and it said something about the ports were set to down down. So what command do I type to get them to up up. Also, what does the no shut command accomplish?

Re: Make Fiber Ports Live on Catalyst 3750?

How far does the fiber run ?

Since you are using a MM fiber, are you using a MM gbic ?

Your line protocol/interface status is down, which means it could be bad gbic, or could be that the cables are not patched properly. Like I said, two switches cannot be connected back to back with out using a cross over cable (Unless the port supports AutoMDIX - which is only on copper).

So Tx of one end should go to Rx of other and vice versa. Check your cabling.

New Member

Re: Make Fiber Ports Live on Catalyst 3750?

Fiber is running about 400 feet. Nothings wrong with the fiber from the corner cabling systems (fiber patch panel). That fiber line is currently in production and working fine with older switches we are temporarily using until we can figure out how to get these 3750's to talk to each other. I'm 90% sure it's a MM gbic. I'll check on that. I doubt it's a bad gbic issue because neither gbic we tried worked and they are both brand new from cisco. Even if the switches came already with ports enabled. Something may have happened so what's the command to enable them?

Purple

Re: Make Fiber Ports Live on Catalyst 3750?

Get on the switch and do a show interface status , the ports in question should show "not connect" if they are enabled . If they show disable then go into the interface and do a "no shut" command .

New Member

Re: Make Fiber Ports Live on Catalyst 3750?

Double check the cabling. Unplug one of the patch cables from one of the gbics. Look at which connector on the gbic has the light coming out of it. Compare to the fiber patch for which connector has light coming out of it. Ensure you have the fiber plugged into the gbic such that light from one connects to dark on the other. Do this at both ends.

Also, pull the gbics out of the switches & validate both are appropriate for the fiber type you are using. 1000-LX is for single mode fiber; 1000-SX is for multimode fiber.

If you have the interface administratively shut down, this will fix it:

int gig 0/1

no shut

New Member

Re: Make Fiber Ports Live on Catalyst 3750?

we don't have that type of gbic. it's an LC connection so you can't flip the cable upside down or only put one in. it's only one way it goes in. But I will try the initiate command.

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