Andy Wade wrote:

Yup, when working with signals that are sent as a differential pair,
it is vital to make sure they are carried by a twisted pair. Just
having the right pins joined together is not enough at these frequencies.

It's also important to maintain the twisting of each pair right up as
close as possible to the IDC terminals of the socket. The 'as
installed' picture provided didn't show particularly good practice in
this respect.

Indeed. You will usually get away with it at 10Mb, and often at 100Mbit,
but don't expect gigabit to like it!

Now can I ask a supplementary Ethernet question about switches while all
the networking experts are around? Can you cascade the cheap unmanaged
switches /ad-infinitum/ and maintain communication between all nodes?

With switches - yes, there are no longer any practical limits on
chaining segments. With older style hubs there was a limit as they acted
as simple repeaters, and kept the whole network as a single collision
detection zone. Hence it also had to all run at the same speed.
Switches are smarter. While initially they will behave a little like
hubs (in the limited sense that they will forward all packets to all
ports), they will learn which MAC addresses are on which ports and stop
forwarding traffic to segments unnecessarily.

For example say two ports from a typical 4-port ADSL router, R, each
feed remote 8-port switches, A & B. Each switch provides 7 ports used
to connect local network devices. In this network will a device on
switch A be able to communicate with a device on switch B, via the
switch in R?

Yup, that would be fine.

--
Cheers,

John.

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