From: Kenneth Wygand (KWygand@customonline.com)
Date: Thu Apr 22 2004 - 22:53:20 GMT-3
Ahmed,
I have confirmed earlier today that if the "mls qos" command is not
enabled, the TOS bits (not COS) will be forwarded _unchanged_. If "mls
qos" is enabled and the ports are _not_ set to trust IP-Precedence, DSCP
or PHB (TOS), the TOS bits will be set back to zeros.
I believe what you are saying is true of the COS bits. If you do not
enable "mls qos", the COS bits will be reset to zero. However, I am
unable to confirm this with my lab setup. Can anyone else confirm this?
Thanks!
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"The only unattainable goal is the one not attempted."
-Anonymous
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Ahmed Mustafa
Sent: Thursday, April 22, 2004 9:25 PM
To: William Chen; ccie2be; Yasser Abdullah; ccielab@groupstudy.com
Subject: Re: mls command
HI William,
I thought it was opposite and that is per Internetwork solution guide,
Lab 7
task 1.6 that states that if the command MLS QOS is not enabled then
switch
will rewrite all the frames with the COS of 0, but you are saying that
the
frames will be send unchanged if MLS QOS is not enabled.
----- Original Message -----
From: "William Chen" <kwchen@netvigator.com>
To: "ccie2be" <ccie2be@nyc.rr.com>; "Yasser Abdullah"
<yasser@alharbitelecom.com>; "'Ahmed Mustafa'"
<ahmed.mustafa@sbcglobal.net>; <ccielab@groupstudy.com>
Sent: Thursday, April 22, 2004 8:36 AM
Subject: Re: mls command
> Hi,
>
> Just to remind that if you enable "mls qos", the default is the QOS
> marking of the packets reveived by every interface is untrust and thus
all
> the packets will override to best-effort.
>
> However, if the "mls qos" is not enabled, switch will forward the
packet
> with the QOS marking unchange.
>
> Therefore, if you set IP Precedence/DSCP in an outgoing interface
of
> Router A connected to Catalyst 3550, and expect the receiving Router B
to
> setup policy according to the packets marking. If you turn on "mls
qos" in
> the Catalyst 3550 but forgot to set the port connected to Router A to
trust
> the marking, the default is all the packets will be override to
best-effort
> (DSCP=0, IP Precedence=0)!
>
> Best Regards,
> William Chen
>
> ----- Original Message -----
> From: "ccie2be" <ccie2be@nyc.rr.com>
> To: "Yasser Abdullah" <yasser@alharbitelecom.com>; "'Ahmed Mustafa'"
> <ahmed.mustafa@sbcglobal.net>; <ccielab@groupstudy.com>
> Sent: Thursday, April 22, 2004 7:44 PM
> Subject: Re: mls command
>
>
> > Hi guys,
> >
> > I'm considering just adding the "mls qos" to both Cat's when I take
the
> lab.
> >
> > Here's my reasoning.
> >
> > There might be certain features besides the obvious QoS stuff that
require
> > this command in order to work properly, for example, certain types
of
> > access-lists that need to examine QoS data inside the layer 3
portion of
> the
> > packet.
> >
> > There's no downside to enabling "mls qos" unless explicitly
forbidden.
> >
> > Does anybody think this is a bad idea? If so, why?
> >
> > Thanks in advance
> >
> >
> > ----- Original Message -----
> > From: "Yasser Abdullah" <yasser@alharbitelecom.com>
> > To: "'Ahmed Mustafa'" <ahmed.mustafa@sbcglobal.net>;
> > <ccielab@groupstudy.com>
> > Sent: Thursday, April 22, 2004 2:19 AM
> > Subject: RE: mls command
> >
> >
> > > As per the command reference guide, 'mls qos' is recommended
before
> > > enabling voice vlan. Until you enter the mls qos command, QOS
processing
> > > is disabled and all CoS values will be mapped to the same queue
(1).
> > >
> > > Brgds,
> > >
> > > Yasser
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf
Of
> > > Ahmed Mustafa
> > > Sent: Thursday, April 22, 2004 8:32 AM
> > > To: ccielab@groupstudy.com
> > > Subject: mls command
> > >
> > > Is command "MLS QOS" required if the port is configured only for
802.1P
> > >
> > > For example,
> > >
> > > interface fastethernet 0/5
> > > switchport voice vlan dot1p
> > >
> > >
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