On 31/07/2018 13:47, Terry Casey wrote:
In article , lid
says...

On 31/07/18 11:33, Terry Casey wrote:
In article ,
lid says...


FTTC gets you 80 if you're lucky, and more likely a lot less if you
aren't next to the cabinet.


That doesn't apply to VM FTTC, though, as the coax
distribution from the cabinet maintains its full 750MHz
(typically) bandwidth throughout the entire coax network so it
doesn't matter where on that network you are connected.

Mmm. There is a length limit on coax though

Yes and no.

There is a distinct difference between a coax network and a
length of coax.

True, signals will be attenuated along the length of the coax,
as with any other type of transmission line, particularly at
the higher frequencies but, at intervals along the route,
amplifiers restore the level and pre-equalise the levels for
feeding the next section so, within limits, levels across the
band are controlled throughout the length of the netork.

Also, the quality of the network is defined in a British
Standard which forms part of the cable operator's licence
terms.

Thus the signals fed to any subscriber on the network will
conform to tightly defined limits which ensure that all
subscribers receive the same level of service.

That is something that BT's copper network cannot do.



Virgin can't either.
Although they have tight control over the signal levels there is the
slight problem of contention. They only have a limited bandwidth
available and its shared with all the subs on a segment.
So you may get 330 Mb/s some of the time you may not get it if there are
a few heavy users on your segment.

This is why virgin were traffic shaping to reduce the throughput of
heavy users and leave some for others.

I don't know what traffic shaping they currently do.

BT suffers the same but the contention is in the links to the ISP not
the access network like virgins. This means that different ISPs may have
different connections and suffer from different levels of contention
depending on what they pay for.

Mine for instance doesn't appear to have any contention as I can max out
the link to the DSLAM whenever I try.