Yes, the wiring *is* that sensitive. To get the noise rejection of
differential signalling down twisted pairs, the pairs need to be both
paired, and twisted. Even half an inch of untwistedness, Hextraspeshally
for the pair which goes across pins 3-6 (widest separation), can cause
much worse performance. Your network will still "work", as the link-layer
and upwards will detect garbles and cause retransmits; but your performance
will be in the Saniflo and margin for errors decreased.
You may well get away with poor wiring practice: the standards are there
so that properly-installed stuff will work over the advertised 100m
length at advertised speeds, with the advertised number of plugs and
sockets along the way (patch panels, etc.) But as you're d-i-y'ing,
do yourself a favour and do the job right. The proper punchdown tool,
rather than the plastic toy; keeping the twists in place; not pulling
hard on the cable or putting excessively sharp bends in the route (a
1 inch/3cm min radius is good, 2in/5cm better); no nasty staples (they
push the wires too close together), rather nice loose cable ties -
that's the way to go. Do it right once, and forget about it for the
next 10 years.
On 11 Nov 2003 23:46:53 GMT, firstname.lastname@example.org wrote:
We seem to be getting away with it OK
RX packets:117723153 errors:0 dropped:0 overruns:0 frame:0
TX packets:131344062 errors:7 dropped:0 overruns:7 carrier:7
The cable lengths are much shorter than 100m, maybe 20-30m for the longer
runs. Another office with a similar setup, but with longer cables (4 storey
building) also works fine, although that is only running at 10Mbps. That
office has an even worse setup, as it still has the 25 pin wall sockets
left in place, with RJ45 adaptors plugged in with around 2 inch of floating
wire in the adaptor. Dunno if the overall screening on the serial cable
would make a difference.
If we ever do rewire it will be done, right, but our bodge has been
forgotten about for the last 8 years.
On Tue, 11 Nov 2003 14:38:59 -0000, "David W.E. Roberts"
Ick - that's the nastiest looking socket I've seen! The Krone ones I
used here look like this:
The stickers are for following different wiring regs.
This is my punchdown tool:
The layout of the stickers show which wire goes where, and you're
right in that the pairs are fed down the centre of the pins then split
and fed to each position. The punchdown tool both inserts and clips
the wire so it's really worth getting a real one if you can.
Stefek is also right about the sensitivity - up here in the control
tower the connection speeds are spot on, but downstairs in the living
room it's noticeable slower so I've obviously b0rked something when I
was running the cables. Not sure what though - no excessive bends, no
cable ties etc.
This helps quite a bit.
The pairs would go
The tricky bit with this kind of indication is working out
which way around the individual wires of a pair go.
If these are the only sockets you are using it dosn't
matter if you are consistent. It does become a problem
if you are using different sockets/patch panels.
Whatever. Just don't pull the cable tie too tight.
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