RE: 100TX using "Cross Over UTP CABLE" limitation

[Ralph.Andersson@xxxxxxxxxxx]

Sir,

1. The pin representation of the RJ45 Twisted Pair link segment connector
is graphically displayed in Figures 14-20 and 14-21 of the IEEE Std 802.3,
1998 edition.  The requirements for the 100BASE-TX crossover function are
spelled out in section 25.4.6 of the same document.  Application notes from
transformer manufacturers will oftentimes show termination schemes for the
unused pairs 4/5 and 7/8.  Also, the obvious must be stated: 1 and 2 are a
twisted pair and, 3 and 6 are a twisted pair; they must not be separated at
any point other than at the connector.

2. Cross cable connections routinely extend out to 140m.  If item 1. is set
up correctly, perhaps you are using an inferior transceiver.

...Ralph








"Jos
¨¦

Ángel" <mormorjo@xxxxxxxxxxx> on 01/11/2000 09:25:44 AM
                                                                           
                                                                           
                                                                           


                                                              
                                                              
                                                              
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 Subject: RE: 100TX using "Cross Over UTP CABLE" limitation   
                                                              







I have read your consult to ieee.org about limitation using 100TX in Cross
Over UTP Cable.

The ISO norm does not reccommend length over 90 metres for transmissions at
100 mbps although it may work at 10 mbps.

I can see you know how to connect the eight wires of the RJ45 but I can't.
I have tried several times with different positions and it does not work.

I may be starting putting them in the wrong position of the RJ45.

The positions of the wires I have at the moment are

    Connector 1     Connector 2
            1                    3
            2                    6
            3                    1
            4                    4
            5                    5
            6                    2
            7                    7
            8                    8

but I don$B!-(Bt know it the protrusion of the RJ45 is upside or downside.
Somebody reccomended me this kind of position but I am not sure if this is
the right one.

Could please help me with this problem? Have you got any scheme or leaflet
about this?



Many thanks and forgive my poor technical English.

Jos
¨¦ Angel Moreno
M¨˘laga (Spain)

I have read your consult to ieee.org about limitation using 100TX in Cross Over UTP Cable.

 

The ISO norm does not reccommend length over 90 metres for transmissions at 100 mbps although it may work at 10 mbps.

 

I can see you know how to connect the eight wires of the RJ45 but I can't. I have tried several times with different positions and it does not work.

 

I may be starting putting them in the wrong position of the RJ45.

 

The positions of the wires I have at the moment are

 

    Connector 1     Connector 2

            1                    3

            2                    6

            3                    1

            4                    4

            5                    5

            6                    2

            7                    7

            8                    8

 

but I don´t know it the protrusion of the RJ45 is upside or downside. Somebody reccomended me this kind of position but I am not sure if this is the right one.

 

Could please help me with this problem? Have you got any scheme or leaflet about this?

 

 

 

Many thanks and forgive my poor technical English.

 

José Angel Moreno

Málaga (Spain)