What's the maximum speed of a typical broadband cable?

  • Thread starter Thread starter Bruce Lee
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Bruce Lee

And what are the hardware restrictions that cap it? Just wondering how it
compares to a Cable TV cable. Are they both fibre optics?
 
The typical broadband cable system is part of a video system and uses fiber optics to a local node, and copper coax cable from the node to your house or business. The bandwidth depends on how much the system operator wants to allocate for the data channel; most of the bandwidth is used for video. The data channel is usually about 3 megabits/sec.
I have read about, but don't have any first hand knowledge about, systems that have fiber optics directly to your home or business. The bandwidth is limited by the hardware on either end; theoretically terabits/sec, but it practice gigabits/sec.
 
Partially it's up to the provider, and partially the medium.

Roughly speaking:

Cable is good to 10 Megs
Twisted-Pair (Cat-5 or 6) can go to 100 Megs
Fiber can go to 10 Gigs

These are bits, so you have to divide by eight to get bytes.

Capacity notwithstanding, the provider can limit the amount of bandwidth
you actually get. On Time Warner you'll get maybe 5 megs down, but they
cap it at under 400k up.
 
Oh, also, in case it's not obvious, the slowest part of the connection
will determine your overall speed. (Weak link in the chain)

So, even though the provider may have fibre running into the gigs, and
you might have twisted-pair running at 100 megs, if you're on cable the
best you could expect was 10 megs.

In other words, you'd need your own fiber connection straight into the
computer to really see gigs of bandwidth.
 
I have read about, but don't have any first hand knowledge about, systems
that have fiber optics directly to your home or business. The bandwidth is
limited by the hardware on either end; theoretically terabits/sec, but it
practice gigabits/sec.
Click to expand...



"Fiber to the curb" gives a couple of my clients between 2 and 3 Mbits both
down and up. What's weird is that is will swing wildly from lo to high with
about a 1 Mbit range. VERY nice upload though.
I'm guessing that this two is capped by the local telco, Sprint. I doubt if
even "Fiber to the curb" setup's are left wide open anymore. All it would
take is one 'tech pirate' with a small home network to soak up all the
bandwidth the nearest DSLAM could handle. Of course Sprint would then
throttle his ass down to 64K, so I don't know...maybe some are still left
open.
--


"I don't cheat to survive. I cheat to LIVE!!"
- Alceryes
 
I was thinking that TV in the future will be internet based if the physical
pipes are big enough - which I would imagine they are. Anyone know how much
bandwidth a full screen digital dolby movie would take up - no buffered
crap - 100% reliable picture.
 
I was thinking that TV in the future will be internet based if the physical
pipes are big enough - which I would imagine they are. Anyone know how much
bandwidth a full screen digital dolby movie would take up - no buffered
crap - 100% reliable picture.
Click to expand...

Could you do it with one person? yes
Could everyone do it? no
Average throughput per person on the internet can't be very
high at present, while average # of TV sets on is another
story.

Certainly TV delivery will be digital, but then there's the
issue of quality too. If you simply want to consider MPEG2
then pull out a DVD, note the runtime and divide by the
filesizes. Then add TCP/IP overhead if you meant
traditional internet access methods.
 
If you simply want to consider MPEG2
then pull out a DVD, note the runtime and divide by the
filesizes. Then add TCP/IP overhead
Click to expand...

Depends on the connection because TCP permits retries. But under
normal corcumstances the overhead is taken to be 1 extra bit per 8 bit
byte (12.5%).
if you meant traditional internet access methods.
Click to expand...

Surely streamed video would use UDP and not TCP. Retries are
meaningless in streamed video.
 
My bro in brisbane has cable broadband, compared to my normal 1000kb/
broadband his is about 1500kb/s - 2000kbps depending on who he i
connected to
 
My bro in brisbane has cable broadband, compared to my normal 1000kb/s
broadband his is about 1500kb/s - 2000kbps depending on who he is
connected to.
Click to expand...

You need to measure the speed of the connection from your machine to
the ISPs network gateway machine. ISPs usually provide an internal
speed test for this purpose.

That way you have a consistent measure of speed. There are about 250
other users on the Class C subnet that you are on, so the faster the
ISP can communicate with everyone the better. Once you go out of the
ISP's network onto the Internet, anything is possible in terms of
speed.

Be sure to convert bytes/sec to bits/sec using the standard factor of
9, which includes 1 extra bit per byte to account for TCP/IP overhead.
Some people use a factor of 10 to be conservative and because the
arithmetic is simpler.
 
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