From: Mike Williams (ccie2be@swbell.net)
Date: Thu Sep 25 2003 - 23:49:45 GMT-3
Seems to me if the gig card in the host went to half duplex mode, that
you still shouldn't see collisions on the interface, and here's why:
Collisions on the interface are only collisions on "outgoing" data on
that port, not incoming. If the host mistakely thinks it's in half
duplex mode while the Cisco side thinks it's full, you will see input
errors on the port resulting from A) the host NIC trying to send data,
B) switch (in full duplex) sending data while receiving and C) the host
"thinking" a collision has occurred and it stops sending the frame
resulting in a runt and/or CRC input error.
This kind of thing happens all the time when a switchport/host is forced
to full duplex and the other end is on autodetect..... The auto detect
end of the connection will fail to half duplex and the other end will
get errors (i.e. if the switch is forced to 100 full, the host on
autodetect will fail to half duplex, and the switchport will see input
errors resulting from the duplex mismatch).
Mike W.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Barney Gaumer
Sent: Thursday, September 25, 2003 10:59 AM
To: Ralph Simmons; ccielab@groupstudy.com
Subject: Re: gig ethernet/ collision debate
If the Gig card in the host that is attached to the
switchport is malfunctioning or has the ability to go
half duplex (and is) then you would see your collision
counter incrementing up.
But if both sides are FDX and no problems then
collisions should not occure.
Cheers,
Barney
--- Ralph Simmons <ciscoag2000@yahoo.com> wrote:
> so is there any way that you would get collisions
> then on a gig link other then faulty equipment then?
> My buddy says he has seen it before and I saw it
> is not possible. What could of caused a interface
> to show collisions or did he just not know what he
> was looking at?
>
> Barney Gaumer <bagaumer@yahoo.com> wrote:Since
> Duplex is not a settable option (at least on
> 6509 platform) you should not see collisions on
> either
> fiber or copper since it is Full Duplex by default.
>
> Again, 6509 is the only platform I have looked at
> this
> on, if other platforms can change Speed/Duplex on
> Gig
> someone else will half to speak to that. I think Gig
> is inherently FDX though.
>
> 6509-a (enable) sh port 3/7
> Port Name Status Vlan
> Duplex Speed Type
> ----- -------------------- ---------- ----------
> ------ ----- ------------
> 3/7 notconnect 1
> full 1000 1000BaseSX
>
>
> 6509-a (enable) set port speed 3/7 1000
> Feature not supported on Module 3.
> 6509-a (enable) set port dup 3/7 full
> Feature not supported on Port 3/7.
> 6509-a (enable)
>
>
> 6509-a (enable) sh port 9/1
> Port Name Status Vlan
> Duplex Speed Type
> ----- -------------------- ---------- ----------
> ------ ----- ------------
> 9/1 notconnect 1
> full 1000 1000BaseT
>
>
> 6509-a (enable) set port speed 9/1 1000
> Feature not supported on Module 9.
> 6509-a (enable) set port dup 9/1 full
> Feature not supported on Port 9/1.
> 6509-a (enable)
> --- Ralph Simmons wrote:
> > Hoping one of you guys can settle a debate i am
> with
> > a coworker and win me a free lunch from him.
> >
> > We were debating about wheter of not you can get
> > collisions on gig ethernet. Is the collision
> > detection removed from gig ethernet? If not under
> > what circumstances could you get collisions? Any documentation of
> > cisco.com would be great to prove it.
> >
> > Thanks,
> >
> >
> > ---------------------------------
> > Do you Yahoo!?
> > The New Yahoo! Shopping - with improved product
> > search
> >
> > ***Get your CCIE and a FREE vacation:
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> >
>
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