From: Bob Sinclair (bsin@cox.net)
Date: Sat May 29 2004 - 19:11:21 GMT-3
Tomasz,
On Ethernet you will need some kind of trunking protocol, either ISL or
dot1q, in order to have a field in which to place the CoS value. 802.1p
refers to the 3 CoS bits in the 802.1q spec. 802.1p as a "trunking" method
is just 802.1q with VLAN ID 0 sent on the native vlan. Purpose is to carry
CoS without actually multiplexing different vlans.
HTH,
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net
----- Original Message -----
From: "Tomasz Szymaqski" <tomasz.szymanski@trecom.pl>
To: <ccielab@groupstudy.com>
Sent: Saturday, May 29, 2004 4:51 PM
Subject: Re: Cos and 802.1p difference/Voice Vlan
> This answer is not really clear to me.
>
> I would like to know if CoS is only in dot1p bits or if untagged
> (without dot1p/dot1q hader) packets can have CoS assigned??????
>
>
> Dan Shechter Gelles wrote:
>
> >dot1p is a field in dot1q.
> >no dot1p no CoS
> >
> >
> >
> >On Sat, 29 May 2004, Tomasz Szymanski wrote:
> >
> >
> >
> >>Hi all,
> >>
> >>I have the question about the difference in Ethernet frames (taged and
> >>untagged).
> >>
> >>Where is the difference in CoS in untagged frame and dot1p priority in
> >>tagged frame.
> >>The question is about voice vlan and it's behaviour.
> >>
> >>I would like to know if the frames from the computer connected to the
> >>IPPhone are tagged or not by the IP phone and how they are tagged.
> >>
> >>I would like to know what happens to the frames if I don't have trust on
> >>the port and default CoS is set to 1. What happens to tagged and
> >>untegged frame in this case?
> >>
> >>TS
> >>
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