hey Peter......... how long were you asleep? <g>
it's just a little jibe resulting from a "simple" thread that went all over
the place!
I had intended on asking if the cables could support at least 1024 macs (to
fit with my cat1912) but then I thought some people wouldn't see the
joke........
have a coffee! :-)
Kevin Wigle
----- Original Message -----
From: "Peter Van Oene" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Sunday, 10 December, 2000 21:40
Subject: Re: Hub-to-Switch connectivity issue
> ok.. i just woke up and may be groggy, but what is a layer 2 cable?
>
> *********** REPLY SEPARATOR ***********
>
> On 12/9/2000 at 5:10 PM Gareth Hinton wrote:
>
> >Layer 2 Cat 5 cables for sale.
> >All MAC addresses configured identical (to make addressing system easy).
> >Anyone interested?
> >
> >In defence of the people who brought DTE and DCE into the argument:
> >
> >It was an analogy, a memory aid for the old folks amongst us. Works for
me
> >(and if I remember rightly, Chuck the elder), so if it confuses or
annoys,
> >please forget it.
> >
> >By the way, the layer 2 cables have been withdrawn until further
development
> >can be carried out. Seems to be some problem with them.
> >
> >Regards,
> >
> >Gaz
> >
> >"John Neiberger" <[EMAIL PROTECTED]> wrote in message
> >4179447.976255551441.JavaMail.imail@puffer">news:4179447.976255551441.JavaMail.imail@puffer...
> >> There is no DTE or DCE in Ethernet-world. Those are serial
communication
> >> terms that do not apply here.
> >>
> >> And hubs are definitely layer one devices, not layer two. To be
> >considered
> >> layer two, they would have to be aware of layer two addressing schemes,
> >> which they are not. They are, however, very aware of the physical
> >> necessities of ethernet communication on a 10 Mbps/Half duplex LAN, and
> >they
> >> do just a bang up job at it.
> >> Regardless, there's no topological difference between a 10baseT LAN
> >> connected to a single hub, and 10base5 LAN devices connected to a
single,
> >> long cable. And I hope no one will try to make the case that the cable
is
> >a
> >> layer two device.
> >>
> >> In Ethernet, your transmit pair must connect to the receiver's receive
> >pair.
> >> Hub and switch ports are wired internally to be crossover ports, or
MDI-X,
> >> so that any ethernet hosts connected to it will have their transmit
pair
> >> connected to everyone else's receive pair.
> >>
> >> This means that if you connect a hub to a hub, a hub to a switch, or a
> >> switch to a switch using a straight cable you are connecting two ports
> >that
> >> are both crossed-over. This will connect the transmit pair of the
first
> >> device to the transmit pair of the second, and consequently the receive
> >> pairs will also be connected. This obviously will not work! That is
why
> >if
> >> one of these devices is a hub with an MDI/MDI-X switch, you would set
it
> >to
> >> MDI to undo the internal crossover. This matches up the pairs
correctly
> >and
> >> communication will proceed.
> >>
> >> If you have two switches, then you have no MDI/MDI-X button to press
and a
> >> crossover cable is required to match up the transmit and receive pairs
> >> correctly.
> >>
> >> I hope that makes sense. As usual, I need to go to bed and get some
rest.
> >> I tend to ramble when I'm sleepy...
> >>
> >> Zzzzzzzzzzzzzzzz,
> >> John
> >>
> >> > DTE to DTE uses cross-over cables.
> >> > Is this correct?
> >> >
> >> >
> >> > ""Bradley J. Wilson"" <[EMAIL PROTECTED]> wrote in message
> >> > 031901c0608a$b9d87d20$ca01010a@bwilson">news:031901c0608a$b9d87d20$ca01010a@bwilson...
> >> > > Okay...I've been digesting the responses I've received about this
> >> issue,
> >> > and
> >> > > what I've come up with can be reduced to two comments:
> >> > >
> >> > > 1) The fact that flipping the MDI/MDI-X switch didn't initially
work
> >> leads
> >> > > me to believe that I wasn't using it right. The fact remains that
> >> > > connecting a hub to a switch must be accomplished using a
crossover
> >> cable.
> >> > >
> >> > > 2) Why is that? It's true that connecting devices at different
> >layers
> >> of
> >> > > the OSI model requires a straight-through cable, and that
connecting
> >> > devices
> >> > > at the same layer requires a crossover cable. So isn't it true
that
> >> > > switches are layer 2, and hubs are layer 1? No. Hubs are
actually
> >> layer
> >> > 2
> >> > > devices, and here's why: while a hub may not understand or care
about
> >> > source
> >> > > and destination MAC addresses, checksums, or what's in the "type"
> >> field,
> >> > it
> >> > > *does* know the rules of CSMACD communication, and has to play by
the
> >> same
> >> > > rules as other layer 2 devices. Therefore, hubs can be considered
> >> Layer 2
> >> > > devices, and thus must be connected to switches with a crossover
> >cable.
> >> > >
> >> > > Anyone see anything wrong with my synopsis above? Let me know.
Just
> >> be
> >> > > careful with your caps lock key. ;-)
> >> > >
> >> > > Thanks,
> >> > >
> >> > > BJ
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > _________________________________
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