pete
Expert Member
I am looking the technical reason why one cannot run Cat5 solid more than 100m, and flex more than 30m. My google skills are failing me. Please help.
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CAT5e Question
- Thread starter pete
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Grouter
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If my IT skills/memory arent failing me atm its because of signal degration.
Packet loss and signal degration may occur if the cable is more than 100m(It will occur more frequently if the cable is longer than that.)
This is the same with flex.
A solution for this problem is inserting a repeater every 100m for Cat5e.
And every 30m for flex.
Please correct me if im wrong
Packet loss and signal degration may occur if the cable is more than 100m(It will occur more frequently if the cable is longer than that.)
This is the same with flex.
A solution for this problem is inserting a repeater every 100m for Cat5e.
And every 30m for flex.
Please correct me if im wrong
FrancTheTank
Expert Member
spiderz
Honorary Master
it's max 100m, with 5 hubs in a row.
pete
Expert Member
I found this:
Timing? As in frequency? As in, packet loss occurs when the TX and RX signals go out of sync due to impedance on the cable?
Timing? As in frequency? As in, packet loss occurs when the TX and RX signals go out of sync due to impedance on the cable?
Didnt see the post but yes I concur.
pete
Expert Member
I ran a 100m flex cable from the pc to the point for two hours yesterday without a single error.
And today I'm going to try a 150m, and then a 200m.
Will post results here.
And today I'm going to try a 150m, and then a 200m.
Will post results here.
There is a time delay for the electrical pulse to travel the length of the cable. The signals travel at around the speed of light - so its not a long delay but it is measurable. Ethernet is designed according to the delay of the electrical signal passing through 200m of cable.
The specs talk about 100m maximum but that is when you are connected to a hub. A hub is simply an amplifier and it does not change the signal. Modern switches are however different: they receive the Ethernet frame, buffer it, and then resend it.
You can in theory do 200m between two devices if you are using a switch or connecting two PC's or routers directly. You should however bear in mind that some devices may not be putting enough power on the line to do the full 200m. But from a timing point of view it is possible.
The specs talk about 100m maximum but that is when you are connected to a hub. A hub is simply an amplifier and it does not change the signal. Modern switches are however different: they receive the Ethernet frame, buffer it, and then resend it.
You can in theory do 200m between two devices if you are using a switch or connecting two PC's or routers directly. You should however bear in mind that some devices may not be putting enough power on the line to do the full 200m. But from a timing point of view it is possible.
pete
Expert Member
Interesting, thank you ambo.
Its a theoretical/estimate/recommended length - it doesn't mean you won't be able run 110m
Anyone ever worked with STP? Now that was fun to drag over distances.
SteveO
Expert Member
its called attenuation. It is the degradation of electrical signals due to the physical characteristics of the electrical signals and the hardware used.
basically the 100m is the reliable distance that cat5 can cover where the signals would be received correctly.
so basically if the signals are sent as normal TTL (ie 2.2V - 5V = '1' and 0v - 0.4v = '0') this voltage would degrade over the 100m to say 2.6v high or due to interferrance the low could be recieved as a 0.3v and at this point the signal would still be readable even though it has been altered somewhat.
the length of the link would also be dependant on interferrance, cable quality and the quality of the signal being output. So for instance a laptop might put out 4.5v whereas a desktop might put out a little more than 5v.
....this is my understanding of the limitations....use it dont use it
basically the 100m is the reliable distance that cat5 can cover where the signals would be received correctly.
so basically if the signals are sent as normal TTL (ie 2.2V - 5V = '1' and 0v - 0.4v = '0') this voltage would degrade over the 100m to say 2.6v high or due to interferrance the low could be recieved as a 0.3v and at this point the signal would still be readable even though it has been altered somewhat.
the length of the link would also be dependant on interferrance, cable quality and the quality of the signal being output. So for instance a laptop might put out 4.5v whereas a desktop might put out a little more than 5v.
....this is my understanding of the limitations....use it dont use it
pete
Expert Member
its called attenuation. It is the degradation of electrical signals due to the physical characteristics of the electrical signals and the hardware used.
basically the 100m is the reliable distance that cat5 can cover where the signals would be received correctly.
so basically if the signals are sent as normal TTL (ie 2.2V - 5V = '1' and 0v - 0.4v = '0') this voltage would degrade over the 100m to say 2.6v high or due to interferrance the low could be recieved as a 0.3v and at this point the signal would still be readable even though it has been altered somewhat.
the length of the link would also be dependant on interferrance, cable quality and the quality of the signal being output. So for instance a laptop might put out 4.5v whereas a desktop might put out a little more than 5v.
....this is my understanding of the limitations....use it dont use it
The most comprehensive explanation yet. Appreciated.