Can a regular fast Ethernet switch use CAT3 wiring instead of CAT5 wiring to transmit 100Mbps over short distances? CAT3 is usually used in telephone networks, and I know it can support 10Base-T at 10Mbps. 100Base-T aka Fast Ethernet is supposed to have CAT5 at minimum. What happens if CAT3 is used? I know it is not recommended, but will it work, or will the switch auto fall back to 10Mbps?
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100Mbps Using CAT3 on short distances? 3
- Thread starter ispwiz
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Some of the older runs I work with are cat3 and they run 100Base-T just fine. The longest run is around 150'.
This is not an endorsement of this practice but in all the cases I have tried it worked fine. Did have to re-terminate one or two due to shoddy workmanship.
In NO case should you install cat3 as a cost saving measure.
Your Mileage May Vary
This is not an endorsement of this practice but in all the cases I have tried it worked fine. Did have to re-terminate one or two due to shoddy workmanship.
In NO case should you install cat3 as a cost saving measure.
Your Mileage May Vary
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wires,
This is EXACTLY what I wanted to know. Do you have any recommendations or advice? I would love to use CAT5, but the CAT3 wire is the only real option. It would cost quite a bit of money to run new wire due to brick walls.
Were you able to actually transmit 100Mbps?
This is EXACTLY what I wanted to know. Do you have any recommendations or advice? I would love to use CAT5, but the CAT3 wire is the only real option. It would cost quite a bit of money to run new wire due to brick walls.
Were you able to actually transmit 100Mbps?
A managed switch would be good so you can keep an eye on error counts. You can get a Dell 3024 switch for under $75 on eBay. With software version 6.1.2.3291 you get statistics, counter summary, errors received which will tell you real fast how your wiring is performing.
As I said before I get 100M but the terminations HAVE to be correct. Twists have to be maintained and the cables cannot be damaged. A bunch of old telephone wiring on 66 blocks will likely need rework.
If you have the choice rewire. Don't try to be a penny pinching hero and have the whole enterprise go down in flames. If this is a new place you are moving into think about how difficult it will be to rewire once everything is moved in and everyone is ready to work. Test BEFORE use.
Good luck.
As I said before I get 100M but the terminations HAVE to be correct. Twists have to be maintained and the cables cannot be damaged. A bunch of old telephone wiring on 66 blocks will likely need rework.
If you have the choice rewire. Don't try to be a penny pinching hero and have the whole enterprise go down in flames. If this is a new place you are moving into think about how difficult it will be to rewire once everything is moved in and everyone is ready to work. Test BEFORE use.
Good luck.
Make sure your wiring is actually CAT3 and not just older beige jacketed station wiring that was installed long before the Telcos cared about packetized digital transmission or whether you have 7, 11 or 17 twists per inch.
(31 year telco veteran)
NCSS NCTS NCTE
(31 year telco veteran)
NCSS NCTS NCTE
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jimbopalmer
Programmer
may be cheaper than re-wiring. If you have a whole building,
I tried to remain child-like, all I acheived was childish.
I tried to remain child-like, all I acheived was childish.
I can see using a CAT3 cable or an extender for a one off situation that you have no choice, but for a whole company?
What happens when half of it works and half of it doesn't?
Or it is inconistent? Unreliable?
Who do you blame then? My take on this is if you cannot afford to do it right don't do it at all. Just put a phone one everyone's desk and say "we like to pretend this is 1984", we don't need a network.
As a network engineer I would not install a customer network running on CAT3. I would walk away and save the headache for someone else who likes them.
My 2 cents on this subject.
What happens when half of it works and half of it doesn't?
Or it is inconistent? Unreliable?
Who do you blame then? My take on this is if you cannot afford to do it right don't do it at all. Just put a phone one everyone's desk and say "we like to pretend this is 1984", we don't need a network.
As a network engineer I would not install a customer network running on CAT3. I would walk away and save the headache for someone else who likes them.
My 2 cents on this subject.
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I am aware of the VDSL solutions that enable 100Mbps over CAT3, but I am trying to avoid that solution. VDSL is still very expensive.
This is for a townhome compex. There are 20 building each with 7 houses. At the end of each building the seven CAT3 cables terminate. I plan to run fiber to each building, and then was hoping I could service each house house using the CAT3 cables.
I know AT&T uverse does the with VDSL, but those runs are usually much longer (0-1500 FT). From one end of the building to the other is max 150 FT, and each run gets 20 FT shorter from there. All of this CAT3 wire is new, we are not talking about 30 year old CAT3 cable here. I would love to run newer CAT5e cable, but I believe install cost would be to high and would require premession from every townhome owner to gain access to their attic.
This is for a townhome compex. There are 20 building each with 7 houses. At the end of each building the seven CAT3 cables terminate. I plan to run fiber to each building, and then was hoping I could service each house house using the CAT3 cables.
I know AT&T uverse does the with VDSL, but those runs are usually much longer (0-1500 FT). From one end of the building to the other is max 150 FT, and each run gets 20 FT shorter from there. All of this CAT3 wire is new, we are not talking about 30 year old CAT3 cable here. I would love to run newer CAT5e cable, but I believe install cost would be to high and would require premession from every townhome owner to gain access to their attic.
VDSL, ADSL, ETHERNET are all different and have different transmission requirements and bandwidths. The CATEGORY rating refers to the ETHERNET transmission protocol. So you can't compare one to the other, apples and oranges!! There are a variety of factors that come into play when you try to apply a set of specifications from one class to another class.
In regards to trying to use 100BaseT on CAT3 cable, it may work for a while but you may end up with a lot of problems:
excessive crosstalk, dropped packets, excessive resends, interference, etc. With those types of conditions it will take longer to send data or files, cause more bottle necks, to get it right, and end up with unhappy customers.
....JIM....
In regards to trying to use 100BaseT on CAT3 cable, it may work for a while but you may end up with a lot of problems:
excessive crosstalk, dropped packets, excessive resends, interference, etc. With those types of conditions it will take longer to send data or files, cause more bottle necks, to get it right, and end up with unhappy customers.
....JIM....
jimbopalmer
Programmer
Cat 3 is going to work fine for 10 meg ethernet. (it will even do full duplex) 100 meg fiber to each townhouse and seven 10 meg clients by 20 buildings is 1.4 gig total bandwidth. That is a LOT of bandwidth to provide.
I tried to remain child-like, all I acheived was childish.
I tried to remain child-like, all I acheived was childish.
robertjo24
MIS
The fact is that you can run 100 Mbit over the Cat-3. It is not a good idea, but you can do it. I agree with the suggestion to have a managed switch so you can keep track of the errors, because there will be errors.
My suggestion for you if you proceed with the connections as you have laid out is to clearly document what you have done, and how it deviates form all recommended practices. I would make sure who ever is managing the end user/customers understands there could be performance issues at the end user level. As long as all parties involved are aware of, and understand the implications of wiring the system this way and agree to the level of performance then you are covered. It is not a matter of whether you will receive interference and errors on the network, it is a matter of how much, and how much your end users are willing to accept.
My suggestion for you if you proceed with the connections as you have laid out is to clearly document what you have done, and how it deviates form all recommended practices. I would make sure who ever is managing the end user/customers understands there could be performance issues at the end user level. As long as all parties involved are aware of, and understand the implications of wiring the system this way and agree to the level of performance then you are covered. It is not a matter of whether you will receive interference and errors on the network, it is a matter of how much, and how much your end users are willing to accept.
A lot of big companies I have worked in recently are limiting all their ports to 10 Mbits again now anyway to increase the overall speed and consistancy for all users. Ever larger files being constantly copied back and forth all over the place are causing speed issues for companies as a whole and putting everyone on 10 Mbits can drastically improve the situation at peak times (for everyone except those copying the 2gig files over the network of course!!)
You may be better off using the cat3 but using it at 10Mbit.
Adrian Paris
Paris Engineering Ltd
Google search of just tech forums & articles
(very useful, honest!)
You may be better off using the cat3 but using it at 10Mbit.
Adrian Paris
Paris Engineering Ltd
Google search of just tech forums & articles
(very useful, honest!)
dialtonebone
Technical User
Like others have said -- walk away if possible.
I would definitely do the Cat5 upgrade.
A (relatively) big cost for now, but down the road alot of flexibility.
I would definitely do the Cat5 upgrade.
A (relatively) big cost for now, but down the road alot of flexibility.
jerryreeve
Vendor
why are the brick walls a limiter for you? you will be replacing the existing cat 3 with a cat 5. Just use the cat 3 as your pull string for the cat 5, this should get you thru the brick without having to re-drill
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'Rule 29', "The enemy of my enemy is my enemy's enemy. No more. No less."
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JerryReeve
Communication Systems Int'l
com-sys.com
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'Rule 29', "The enemy of my enemy is my enemy's enemy. No more. No less."
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JerryReeve
Communication Systems Int'l
com-sys.com
In my business, I see this all the time, folks trying to retro-fit an MDU to provide internet, etc.
Trust me on this, the money you think you're saving by using the existing CAT3 is going to be eaten up in support costs very quickly.
MCSE CCNA CCDA
Trust me on this, the money you think you're saving by using the existing CAT3 is going to be eaten up in support costs very quickly.
MCSE CCNA CCDA
A couple of months ago I set up a phone line without a DSL signal on it so that 2 modems could be connected. One at either end so that one would act as a modem and the other would act as the server. The 2 units would communicate the same as you would on the internet. 2 network cards in the one CPU is supposed to allowed the other to access network and internet.
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