[prev in list] [next in list] [prev in thread] [next in thread] 

List:       systalk
Subject:    Re: [Systalk]Twisted Pair (or) and Crossover?
From:       GK64 () aol ! com
Date:       2001-02-20 6:21:43
[Download RAW message or body]

In einer eMail vom 2/19/2001 11:47:53 AM Pacific Standard Time schreibt 
brad@rupturedcyst.com:

> > Has anyone achieved something approximating 100 mbit on crossover cable.
>  > Read somewhere that a "regular" crossover couldnt be used for 100 mbit. 
No
>  > idea whether thats true..
>  
>  Um, im not even sure how you reach 100 mbit. I have a 10/100 NIC, but was
>  never sure on how to actually reach 100 mbit.
>  
>  Brad
>  brad@rupturedcyst.com
>  
>  
the magic words are  - loose-end reflection -  , - wavelength-adjustment - 
Ttransmision power will be reflectet on open or  wrong fitted ends.
In worst case nothing will get trough.


The Trick at  BNC was. (RG58 / 10base-2 (cheapernet) 
if you dont use the normal 50 Ohm at both ends,
to have an variable resistor at only one BNC connector. (0-100 ohm poti)
this connects, only on one end, the inner line to the outer shield.
!!! You then ping one far crufts IP  and manualy ajust the variable resistor 
to the 33 Ohm region until pings return. ( this is the case when wavelength 
adjustment fits )
 
I have not tried this on UTP!!!!!!!.  

UTP cables have wavelengthresistence from 100 to 150 Ohm ,compared whith RG58 
50 Ohm. 
you should try 200 ohm poti one between  pin TD+TD- 1/2 and one for RD+RD- 
3/6  and pull the lines down to the 66 or 75 Ohm region.

If you can force your cards by some cardsetup program to
use 100b/s and then use the ping until return method. it might work? ;:)



Ok a  100 HUB does all this for you.

gert....

_______________________________________________
DHS Systalk Discussion List Systalk@dhs.org
To manage your subscription, please goto:
http://www.dhs.org/mailman/listinfo/systalk

[prev in list] [next in list] [prev in thread] [next in thread]