the simple facts are as follows:
1) Deciding on a crossover or straight-through cable is a physical layer
problem
2) Depending on which cable you use will depend on how the manufacturer
designed and wired the physical port on each end.
3) ever situation is different, the only reason you rule works most of the
time is that manufacturers try to wire their ports to what will be pluging
into them the majority of the time.
4) you have 2 pairs of wire - pins 1,2,3,6 (Pins 1&2 - Recieve) (Pins 3&6
are transmit)
No matter what you are connecting, the recieve must go to the transmit and
and on the other end the transmit must go the recieve (hence the name
crossover)
5) On hubs & switches most manufactures hardwire the the ports already
crossed, so you don't have to use a crossover cable on a connection to a PC
or Router (routers & NIC's are not hardwired crossed), but you do have to
use a crossover cable on a hub to hub connection because the ports on each
end are crossed (2 cross ports equals the transmit to transmit and recieve
to recieve on a straight-through cable).
6) the MDI/MDI-X switch is used to uncross a port on the HUB - this should
had work for you (you only set one side to MDI) unless you had a cable
problem also. (Link lights do not mean the cable is good.)
I hope this helps you the next time you have a problem.
Randy
""Bradley J. Wilson"" <[EMAIL PROTECTED]> wrote in message
00af01c05b92$825a9060$ca01010a@bwilson">news:00af01c05b92$825a9060$ca01010a@bwilson...
> Okay gang, I had an interesting and annoying situation yesterday morning,
> and I'd like to see if anyone else has had an experience like this:
>
> My client was installing an older BayStack 301 switch into their existing
> network, which consisted of a Bay Access Node router, as well as four
> stacked SynOptics LattisHubs. The router was experiencing excessive
> collisions, hence the installation of the switch. So we installed the
> switch and cabled the router to it, moved all the "power users" directly
> onto the switch, and left the other users attached to the hub. We
attached
> the hub to the switch via a straight-through cable.
>
> The users who were directly connected to the switch had no problem
accessing
> the network and Internet. The users on the hub were dead in the water.
We
> tried swapping out the cable between the hub and switch, tried plugging
> either end into different ports, tried flipping the MDI/MDI-X switch, and
> nothing worked. The only thing that *did* work was using a *crossover*
> cable between the hub and the switch.
>
> Now, the rule (which I gleaned from this newsgroup, btw) is that when
you're
> connecting devices at different OSI layers, you use a straight-through -
> e.g. PC to hub, PC to switch, switch to router, hub to switch - that's all
> straight-through. You use a crossover when you're connecting devices at
the
> same OSI layer - router to router, switch to switch, hub to hub, PC to PC.
> In the situation yesterday, a straight-through seemed logical, as we were
> trying to connect a hub to a switch. Am I wrong here? Why did the
> crossover work?
>
> Thanks,
>
> BJ
>
> P.S. sorry for the Bay-centric example...I'm trying to get them to change
> that. ;-)
>
>
>
>
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