Evaluating STP Quality for Gigabit Ethernet

We are converting over our network slowly to gigabit ethernet, and I wanted to better understand how I can evaluate the quality of the existing copper wiring. We are in a building where the twisted pair wiring was done maybe

15 years ago, and the quality is not very high. I doubt that the patch panels are rated for gigabit ethernet, nor is the twisted pair wiring in the building probably. On the other hand, our runs are extremely short, with maybe 5000 sq feet of office and lab space surrounding a computer room where the wiring terminates.

What distance can gigabit ethernet run reliably over non-qualified CAT5 cabling?

What is the cheapest tester that would give us some way to characterize the quality of patch cables as well as wiring at each wall jack in the building through to its patch panel in the computer room?

Reply to
Will
Loading thread data ...

First off are you sure it even has all 4 pairs connected?

It's hard to imagine you'd get enough positive results to make it worth testing any of it. I'd just take the testing budget and put it into the upgrade plan.

If you are moving to gigabit then I'm sure you're also moving to managed switched. Right? So to make sure you have a mess, hook up your new managed switch to a few runs and walk around the office with a gig laptop and try to watch some streaming video with it. While doing this see what the connection rate is for the laptop and see what the switch is getting for error rates.

Reply to
DLR

Will wrote in part:

In 1991 you'd be luckly to get wired with Cat3. That isn't spoec'd for 100 MHz. are you running 100baseTX successfully? Min errors, congestion or retransmits? If it won't run 100FD, there isn't a prayers of it running gig.

Short helps. But some of your runs are probably 100ft, about 1/3 the max.

Try running `ttcp` software on two machines and see if you get wirespped. Also try full duplex.

-- Robert

Reply to
Robert Redelmeier

You would think, yet we have gigE NetGear GS116 switches in individual rooms uplinked to GSM7224 layer 2 switches in the central room, and I have yet to see a single error reported on any switch. I'm not believing the report somehow.

Where can I get a ttcp that would run on Windows command line?

Reply to
Will

Will wrote in part:

Why do you believe that links are being run at 100, let alone gig? Some very smart equipment falls back to 10. Almost all will fall back to 100.

Search for ttcp or ttcp.exe ?

-- Robert

Reply to
Robert Redelmeier

Because the link lights on the switch, as well as the software application, both say gigabit speed for all attached links.

Reply to
Will

Will wrote in part:

And do you actually see 13+ MByte/s transfer speeds? The lights are often wrong and the software may be if it's just talking to the etherchip.

-- Robert

Reply to
Robert Redelmeier

Yes, we seem to be getting about 12 to 20 MB/sec.

I'm a little perplexed why we see the bandwidth peek around 20 MB/sec then go to zero for a while before jumping again to a peak.

Reply to
Will

We have a printer which does not correctly negotiate when connected to a gig link. We're waiting on a fix from the manufacturer. But until I looked at the error rates, it seemed to be a protocol problem. It would work fine if we sent jobs via AppleTalk. Say 1 minute before printing started. But if we used IP as the transport the same job would take 1 to

3 hours before it would print. When I checked the switch stats, CRC errors outnumbered good packets when doing IP. But until I looked at it everyone was saying our computers couldn't talk IP correctly as it did work with AppleTalk. Turned out the issue was the interface on the printer was much more likely to mishandle large packets when connected to a gig link.

My point is once you have a link with issues, problems can manifest themselves in strange ways.

Reply to
DLR

Will wrote in part:

Definitely gig.

There are a number of possible explanations: If it's quick cycling (ms) it might just be track seek. If it's much slower (s) and erratic, then that may be all the traffic to be sent!

-- Robert

Reply to
Robert Redelmeier

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.