Fiber troubles

[Gorphus]

I have upgraded our old 3Com SuperStack switches to a Cisco 4000 series switch. We were running multimode fiber from one building 2500 feet to another building and then branching out from there to the other buildings in the plant. The Cisco has SC gigabit connections, and our fiber box is ST, 3Coms were the same way. From the 4000 we are running it to a Cisco 3500 with SC gigabit, and then out to some 3Com fiber switches for now. The problem is I cannot get the 2 Cisco devices to see the fiber. I configured them and tested in the same room with a SC-SC patch cable and had no problems. If I put the 3Com equipment back in place it works fine using the same fibers. I am not too familiar with fiber networking cables, is there some way that the fiber we have in place is not gigabit compliant? We are running 48 pairs total, 16 pair are single mode and the remaining are multimode. Thanks in advance.

Jonathan

 

[mikeydidit]

The 62.5 micron multimode fiber only has a distance of limitations of 1650 feet for gigabit ethernet. This may be the problem that you are running to.


Mikey

 

[Gorphus]

Thanks for that information, I could not find anything about the speed vs distance limitations. I am getting with the people who ran our fiber now to see about putting a repeater in line somewhere to fix this.

 

[jimbopalmer]

For 62.5 Micron Multimode Fiber
1000baseSX may only go 220 Meters 722 feet
1000baseLX may go only 550 Meters 1804 feet

For 50 Micron Multimode Fiber
1000baseSX may only go 500 Meters 1640 feet
1000baseLX may go only 550 Meters 1804 feet

For 9 Micron SInglemode Fiber
1000baseLX may go only 5000 Meters 16400 feet 3.1 Miles


I tried to remain child-like, all I acheived was childish.

 

[Jtodd]

Don't forget the lazer optimized 50 micron, it will get you 800m/1000m/1100m depending on which you use.

In my experience, the 220m on the old 62.5 is almost a brick wall limitation. We had some buildings that were boarderline, and they didn't make it.

Because of that and the fact that the standard 550m 50 micron is cheaper than 62.5, were moving to 50 micron for all new installations.



Justin T. Clausen
Physical Layer Implementation
California State University, Monterey Bay