Log In

Come Join Us!

Are you a
Computer / IT professional?
Join Tek-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here



My situation I am LAN admin for a industrial plant about 400 nodes on a 10baset network.  Upgrading to fastethernet but currently wiring is cat3.  Will cat3 support 100mbps?  Advice please, thank you.


No.. no.. no..

CAT3 can have enough troubles with 10 half and voice ;)  Even if it did "work", you would never see the speed of the CAT5 wiring.. nor the distance. ANd when you say "industrial" I hear much "electronic noise" in the air from the vent systems, robotics, heavy equipment, welders and so on and so on.

One thought would be to run CAT5 for the switch/hub interconnects and leave the workstations on the 10 half CAT3. It would at least give you a larger pipe for the "back bone" You could replace the CAT3 on a "as need" basis once that is done and spread the cost out over some time. I have done this very thing with great success where the servers and the switches got the 10/100 links and the workstatiosn stayed on 10 half( old boxes)

Just a thought

Mike S

"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin


Just to echo Mike S's thoughts, "ANd when you say 'industrial' I hear much 'electronic noise' in the air from the vent systems, robotics, heavy equipment, welders and so on and so on."

We moved from Cat 3 to Cat 5 in an "industrial" factory.  After some serious trial and error, we went to fiber optics for the back bone in the plant. We then put Cat 5 from the hubs to the workstations. This is an expensive route but not as expensive as having to trouble-shoot "noise" on a data line or lose of data. We left the Cat 3 in place and now use it for phone lines, fax lines, etc.

You now have all my life savings, about two cents worth.

James P. Cottingham


Thanks guys for the information.  Most likely leave workstations at 10mbps and switches and servers 100mbps.


Just one more thought.. James is quite correct and he jogged yet another wannabe thought loose from these brain cells ;)

Get a few used Cisco 1900s or 1924s.. they are cheap compared to new hardware and the 1900s can come with a 100TX ( fiber) connection for the backbone built in. The fiber runs nowdays is not that expensive.. or should not be given the 3M snaplock connectors and more folks are terminating fiber runs. Just make sure you pull 6 strands if you only need two. That gives you two spare pair for growth or repair. And unless you drive over it with aforklift, it's pretty durable stuff. I've used since the late 80s and can vouch for it (if quality fiber is used)

Goes along with using quality CAT5 cable and connectors. Make sure you get EACH run tested and you get a printout. IF the vendor cant or wont supply that, get another vendor. No *D* rings allowed.. use flat straps and velcro.  I have a nice standards doc I can private email if you want for a basic structure for your cable guys to work from.

Mike S


"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin


Thanks again for the info


We have a number of CAT3 runs that run 100Mbps just fine.  CAT3 can support it if it was installed well (nearly to CAT5 standards - not untwisted over 1/2" at terminations, no sharp bends, etc.) The problem is that while one run may support 100Mbps, another one right next to it, even going to the same wall box, may not.  So it can support it, maybe even reliably, but not necessarily predictibaly.

Follow the advice of the others. Put in a fiber backbone.  The fiber itself can handle gigabit speeds, so if you don't have the budget now you can always upgrade trancievers later while using the same fiber.  Ideally you should use 10/100 switches in your distribution closets connected to each other with gigabit fiber.  That way you have the backbone speed to support multiple 100Mb pipes out of the switches.  If you dont have the budget use older 10/100 switches or hubs as suggested with 100Mb fiber connections.

If your workstations have 10/100 cards and you have 10/100 switches/hubs in the closet, set everything to auto negotiate and  connections that can support 100Mb will come up that way, while the other will come up at 10Mb.  If you have a connection that comes up at 100Mb but has a lot of errors, force the NIC in the workstation to 10Mb.

Once everything is running again, you can redo the drops at your leisure.  When you redo the drops, make sure you redo everything.  CAT3 patch panels and wall jacks have to go as well as the wire.  If you have raceway with sharp bends in it, that will have to go as well.  Look at the cable manufacturers sites for info on wiring CAT5.  True CAT5 performance doesn't just come from the wire, but the way it's terminated and how it's run as well.  

Good luck.

If everything seems to be going well: you don't have enough information.......


I would recommend using your CAT3 as pull string for your CAT5 cabling.

Just a suggestion


What do you mean about "pull string" please get me some info, thanks.


pull string refers to the piece o' string that you toss through the ceiling or through the conduit. You use this string to pull in the cable. Always pull in TWO strings and tie one off for future use. He was refering to using the old cable as the "string" to pull in the new CAT5. That may or may not work as cables tend to wrap themselves around or the "snot" lube used turns to some previously unknown hard substance which cements your cables in place

Mike S

"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin


Thanks for the info, wybnormal.


If you want a lot of good info on installation check out the installer tips at http://cim.pennnet.com/home.cfm which is "Cable Installation & Maintenance" magazine.

If everything seems to be going well: you don't have enough information.......

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Tek-Tips Forums free from inappropriate posts.
The Tek-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Tek-Tips forums is a member-only feature.

Click Here to join Tek-Tips and talk with other members! Already a Member? Login

Close Box

Join Tek-Tips® Today!

Join your peers on the Internet's largest technical computer professional community.
It's easy to join and it's free.

Here's Why Members Love Tek-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close