From: Wade Edwards (wade.edwards@xxxxxxxxxxxxxxxxxxx)
Date: Fri Aug 02 2002 - 18:54:32 GMT-3
This sounds like it works but I can see that it breaks when you are
connecting a switch (Layer 2 device) to a hub (Layer 1 device). You
still need a cross-over cable. I do agree with the statement in general.
L8r
-----Original Message-----
From: Tallis, Kate A [mailto:kate.a.tallis@lmco.com]
Sent: Tuesday, July 23, 2002 8:04 AM
To: 'Asim Khan'; Karl Young; Jake; Tom Young; ccielab@groupstudy.com
Subject: RE: Computer connect to router
Students--
I found a very simple rule governing this in a old CCO document. It said
that when connecting two devices that operated at the same OSI layer
(i.e.,
a router to a router, a router to a PIX, a switch to a switch, etc.) use
a
crossover cable, but when connecting devices at different OSI layers
(i.e.,
a router to a switch) use a straight-thru cable. And, the paper went on
to
say, for the purposes of this rule (only) you should consider a
workstation
a layer three device.
It's not perfect but it's easy to remember and it's worked pretty well
for
me.
Kate
Katherine Tallis,
CCNP-Security
Lockheed Martin Corp.
-----Original Message-----
From: Asim Khan [mailto:asimmegawatt@yahoo.com]
Sent: Tuesday, July 23, 2002 3:11 AM
To: Karl Young; Jake; Tom Young; ccielab@groupstudy.com
Subject: Re: Computer connect to router
Karl
If, according to your rule, similar devices use
crossover and disimilar use striaght cable, then what
about connection between
1)computer to Router
2)Router to Firewall
3)Firewall to VPN Concentrator etc...
All these connections need Crossover cable. You can
verify this in the lab. Please read my previous
explanation, you'll understand the concept.
Regards.
Asim Khan
--- Karl Young <kaelwyoung@netscape.net> wrote:
> The Rule I have always used is this : If you have
> two of the same devices Use a X-over. all else use a
> straight thru.
>
> Viz: Two computers connected back to back X-over
> Two Routers connected back to back X-over
> Two HUBs " " " X-over
> Two Switches " " " X-over
>
> ALL Else use
> Straight Thru.
> Karl.
>
>
>
>
> <jakeczyz@yahoo.com> wrote:
>
> >Well said!! The only other thing I might add is
> that you can think of it in terms of DTE
> >and DCE. Whenever you connect two DCE together or
> two DTE together, you'll need to
> >crossover, otherwise use straight through. Since
> routers, firewalls, and, of course, PC's
> >are all considered DTE (data terminal equipment)
> while switches, hubs, and bridges are
> >considered DCE (data communications equipment) the
> rules make sense.
> >
> >Just my $.02 worth.
> >
> >HTH,
> >Jake
> >9102
> >
> >
> >--- Asim Khan <asimmegawatt@yahoo.com> wrote:
> >> Tom,
> >>
> >> The decision when to use Cross and when to use
> >> straight cable depends upon the interface type.
> By
> >> defualt all the interfaces are grouped in two
> classes;
> >> MDI (media dependent interface) and MDI-X (media
> >> dependent interface-Crossover i.e internally
> crossed).
> >> All the end devices have MDI interfaces like
> Routers,
> >> Computers, Firewalls etc. Whereas all the
> intermediate
> >> devices have MDI-X interfaces like Switches and
> Hubs.
> >> So when you connect two MDI interfaces you will
> have
> >> to use Cross cable. Similarly between MDI and
> MDI-X
> >> interfaces you have to use Straight and between
> two
> >> MDI-X interfaces you have to use Cross. So from
> above
> >> discussion we conclude
> >>
> >> Computer to Router ----> Cross Cable
> >> Router to Router ----> Cross Cable
> >> Computer to Computer -----> Cross Cable
> >> Computer to Switch/Hub---> Straight Cable
> >> Router to Switch/Hub ----> Stright Cable
> >> Switch to Switch -----> Cross Cable
> >>
> >> Remember on some Hubs we have uplink port which
> can be
> >> changed from MDI to MDI-X and vice versa through
> the
> >> toggle switch located near the uplink port.
> >>
> >> Hope this helps.
> >>
> >> Asim Khan
> >>
> >>
> >> --- Tom Young <gitsyoung@yahoo.co.jp> wrote:
> >> > Hi, group
> >> >
> >> > A very simple question ,may I use crossover
> cable
> >> > to
> >> > connect a computer to router's ethernet port
> >> > directly?Certainly I will set the port address
> and
> >> > computer's address in one subnet.
> >> >
> >> > Thanks
> >> >
> >> >
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