[TriLUG] ethernet ports on Linksys wrt54g are autosense

Victor Snesarev vnsnes at yahoo.com
Thu Oct 21 08:44:23 EDT 2004


--- Jeremy Portzer <jeremyp at pobox.com> wrote:

> On Thu, 2004-10-21 at 06:59, Joseph Mack wrote:
> 
> > So I called up Intrex about the switches that someone on
> > this list had recommended to find that the Intrex switches 
> > didn't have an X - straight switch because they didn't need 
> > one - all the ports were autosense. I didn't know such things 
> > existed and it occured to me to test the wrt54g ports for 
> > autosense. 
> 
> Actually, this is pretty much standard on all new switches and routers
> and such.  The days of having to worry about cross-over cables or
> straight-through are happily numbered.
> 
That feature is called Auto-MDI/MDI-X. MDI stands for Media Dependent Interface
and is an IEEE 802.3 standards term. In this case the MDI is an 8-pin RJ45 with
2 twisted pairs of wire. The X stands for crossover (Xover). So, Auto-MDIX =
Automatic twisted pair crossover.

I believe, the way Auto-MDI/MDI-X works is that the Ethernet PHY (physical
layer) devices switch between MDI and MDI-X at random time intervals until
signal is detected at both ends.

WRT54G user manual says, "All Ethernet Ports Support Auto-Crossover
(MDI/MDI-X)—No Need for Crossover Cables".

Victor



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