From: Jason Sinclair (sinclairj@xxxxxxxxxxxxxxx)
Date: Thu Jul 25 2002 - 22:19:23 GMT-3
All,
Both Asim and Jakes answer were the most accurate.
This is a fundamental issue and one I think must be known in order to work
in this Industry. The simple answer is that all devices can be considered a
DTE or a DCE, right? Now we also know that the transmit and receive pairs on
a DTE and a DCE are reversed, allowing them to work. So if you want to know
whether you require a crossover or straight through cable, then you need to
verify if your device is DTE or DCE and use the appropriate cable. I don't
mean to burst anyone's bubble here, however this is a fundamental aspect of
networking that should be understood.
Also Karl, you can connect a switch to a switch with a straight through
cable. Review Asim's logic to see why.
Just as an aside, perhaps cabling should have been left in the lab? - Just a
jibe.
Regards,
Jason Sinclair CCIE #9100
Manager, Network Control Centre
POWERTEL
55 Clarence Street,
SYDNEY NSW 2000
AUSTRALIA
office: + 61 2 8264 3820
mobile: + 61 416 105 858
email: sinclairj@powertel.com.au
-----Original Message-----
From: kaelwyoung@netscape.net [mailto:kaelwyoung@netscape.net]
Sent: Friday, 26 July 2002 10:34
To: asimmegawatt@yahoo.com; jakeczyz@yahoo.com; gitsyoung@yahoo.co.jp;
ccielab@groupstudy.com
Subject: Re: Computer connect to router
Asim ,
When I use the term router I am refering to the routing function not
a BOX . When I use the term switching I refer the fuction switching .For
all intent and purposes if you were connecting to bricks back to back that
performed a similar function use a x-over cable otherwise use a straight
cable .that is the rule.
Karl.
Asim Khan <asimmegawatt@yahoo.com> wrote:
>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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