Ethernet Cable Frequency

[Spearball]

I have a question.

What frequency in MHZ does a lan work at. Does it depend on the speed of the network. Are ethernet ports (like on computers and routers, etc) auto sensing when it switches to another frequency?

[Lespaul20]

Ethernet itself isn't specified by it's electrical frequency. The cabling has minimum frequency requirements but Ethernet is described in bits per second. Your Ethernet equipment will run at the speed of the slowest device.

[Spearball]

I was looking at a chart that says,

Cat 5 provide up to 100MHZ
Cat5e(enhanced) 100MHZ
Cat6 250MHZ/ Gigabyte networks
Cat6a(enhanced) 500-550MHZ/ Gigabyte and supports 10 GB networks

I still don't really understand. Isn't higher better?

[Floppyman]

I explain this a little bit in an article I wrote for PCM a while back:

Ethernet Networking Fundamentals (http://www.pcmech.com/article/tech-indepth-ethernet/)

The short answer is that higher can be better. Think about this: Imagine you can only push two bits of data at a time. Then you would get more resultant bandwidth if you can push two bits at a frequency of 500 million times per second (500MHz) over just 250 million times per second (250MHz) or less (1000Mbit/s vs. 500Mbit/s -- i.e. 1 billion bits/s vs. 500 million bits/s)

HTH

[Spearball]

Hum that small explanation really made it click Floppyman. If i understood this right, you can compare it to an older p4 cpu vs athlon 64. The athlon 64 could have took much more data (mbits/s) at a slower clock rate (frequency). P4 was the opposite. I never though networking would be similar. Thanks. I'm going to read the guide anyway.

Now that i kind of understood (maybe im all wrong) the question is how do you make the network work at higher frequency's?

[mbossman2]

the user doesn't drive (or select) the operating frequencies, the devices connected do.

the devices establish mutual ground upon which they communicate.

to think of it in other terms: modems communicate with each other and establish the maximum data speeds that they can communicate, network devices do the same thing and can alter their settings on the fly.

AFAIK, there are no settings, in any switch, that allow the network admin/engineer to alter the fundamental frequency settings.

[Spearball]

Basically if you have a cat 6 cable and your device needs to operate at 250 MHZ for optimal performance it automatically switches.
Can all NIC's operate at high frequencies or does it go my bandwidth. Like to 100mbit/s nics only go a maximum of 100 MHZ.

Sorry im more into hardware i never really looked at networking.

[glc]

100 mbit nics will operate full speed with any cable CAT5 or better and as long as all other devices it must communicate with are 100 mbit or better.

[Spearball]

All right thanks a lot guys! Really cleared some networking things up.