Peter,
Here's the long and the short of it.
Ethernet 10BASE-T will in fact not function through either of the jack
configurations you ask about.
An RJ45 jack was used by the phone companies for the delivery of data
services before adjustable interface devices (from a signal level
perspective) were available. An RJ45 outlet delivers a 2 wire data service
to pins 5 and 4 (Tip and Ring) and has a programmable resistor across pins 7
and 8 that was used for adjusting the signal level delivered to the
customer.
An RJ48 jack used to be used on the customer demarcation jack for DS1
circuits. This jack delivered the DS1 Transmit signal to pins 2 and 1 (Tip
and Ring) and the receive signal to pins 7 and 8 (Tip 1 Ring 1). An RJ48S
jack also has a hard loop connection built in that routes the transmit
signal to the receive pairs when the line cord is removed.
Ethernet 10BASE-T uses pins 1 and 2 to transmit and pins 3 and 6 to receive.
In today's environment of structured cabling systems the standard jack
configurations for data cabling are referred to as T568A and T568B. These
jack configurations have all four pairs of the UTP cabling terminated as
follows:
T568A
Pin 1 Pair 3 Tip
Pin 2 Pair 3 Ring
Pin 3 Pair 2 Tip
Pin 4 Pair 1 Ring
Pin 5 Pair 1 Tip
Pin 6 Pair 2 Ring
Pin 7 Pair 4 Tip
Pin 8 Pair 4 Ring
T568B
Pin 1 Pair 2 Tip
Pin 2 Pair 2 Ring
Pin 3 Pair 3 Tip
Pin 4 Pair 1 Ring
Pin 5 Pair 1 Tip
Pin 6 Pair 3 Ring
Pin 7 Pair 4 Tip
Pin 8 Pair 4 Ring
The term "RJ45" is used way too much in this industry in my opinion. One
can still purchase "RJ45" jacks and there is always the chance you could
wind up getting what you ask for.
Hope this was helpful.
Thanks,
Mark D. Stoops, RCDD
-----Original Message-----
From: peter whittle [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, June 20, 2000 13:15
To: [EMAIL PROTECTED]
Subject: RJ45 & RJ48 difference
Hi,
What is the difference between an RJ45 connector as used on 10Bt and an
RJ48
connector as used on 120R Primary rate?
They both appear to be the same 8 pin idc connector.
Thanks
Peter
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