[plug] home cat5 issues

Gavin Chester gavin.chester at gmail.com
Wed Mar 19 13:54:51 WST 2008

I have wired the house for cat5 to a six rooms. Installation was
_relatively_ easy by virtue of doing it underfloor in an old wooden
house with suspended timber floors. I basically followed a 'modified'
star topology for my layout. I'll explain 'modified' in a moment ;-). 

I had all the right gear to do it all myself: rj45 crimp tool,
connectors, keystone/modular rj45 sockets, punch-down tool, cat5e cable,
and lan cable tester with passive remote id units for cable identity and
testing. All sockets and patch cables tested good to cat5 specs. Only
thing I haven't tested is cable capacitance.

Since trying to use the setup, I have found issues with woeful speed and
none of the sockets working well enough to get an IP from the router. At
this point, I feel sage nodding of heads from the experienced readers,
with issues such as crosstalk, emf, or dodgy connections springing to
your mind :-)

However, I made a test cable to use 'above floor' to replicate my
underfloor setup and the same issues arise. It seems to centre on the
keystone/modular sockets. Each leg of my star topology is 'modified' to
interpose 2-4 keystone sockets along its length. My test cable is like
this with crimped connectors each end and 30m long. If I connect to the
crimped connectors at the extreme ends I get good connection, because
it's just working like a 30m long patch cable. However, if I connect to
one of the keystone sockets along its length and then a short patch
cable to PC then it all falls down. A simple diagram of my modified star
topology may help:

	|			|
	|			|	       
	PC			Router

where each 'O' is a keystone socket and 'X' is crimped cable connector
on a single cat5e cable placed loose on the floor. All connections and
sockets test as good, but only X-X works, any combination of X-O or O-O
fails. WHY? Any ideas welcome. BTW: I have used two brand of keystone
socket, in case that crossed your mind.


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