From: Geert Nijs (geert.nijs@simac.be)
Date: Thu Jan 26 2006 - 07:11:09 GMT-3
Yes, this is true, especially if the router is also bridging or running
DLSW or RSRB.
I have seen a case where the DTP packets were bridged across a DLSW or
RSRB connection to another switch. Switches were trying to
setup a trunk across a DLSW connection :-)
Geert
CCIE# 13729
-----Oorspronkelijk bericht-----
Van: nobody@groupstudy.com [mailto:nobody@groupstudy.com] Namens Jack
Ross
Verzonden: donderdag 19 januari 2006 6:36
Aan: Cisco certification
Onderwerp: RE: DTP
I always use "switchport no-negotiate" when configuring a trunk to a
router. I've seen it cause some strange random behavior if you don't.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Anthony Sequeira
Sent: Wednesday, January 18, 2006 10:20 PM
To: Gary Ring
Cc: T.J. Mitchell; Cisco certification
Subject: Re: DTP
By configuring this command on each end of the link - you completely
stop the sending of DTP frames on this link.
Is anyone listening for them? Well - not sure I care ;-) But since the
trunks are also in UNCONDITIONAL trunk or access mode - I would have to
say no.
On 1/18/06, Gary Ring <garyring.work@gmail.com> wrote:
> Good catch Anthony. It's like you just got your CCIE or something ;-)
It's
> right there in the command reference. I saw it as soon as I read your
post.
> Staring me in the face. Would the port still listen for DTP frames
> in trunk mode? Thanks.
>
> Gary Ring
>
> On 1/18/06, Anthony Sequeira <terry.francona@gmail.com> wrote:
> > You will find many threads on this in the archives - but here is the
> > short answer -
> >
> > You need to set the interfaces to either trunk mode or access mode -
> > AND THEN - you need to use the switchport nonegotiate command. For
> > some reason - everyone seemed to forget that here in this thread!
> >
> > Here is a DOC-CD snippet -
> >
> > switchport nonegotiate - Prevents the interface from generating DTP
> > frames. You can use this command only when the interface switchport
> > mode is access or trunk. You must manually configure the neighboring
> > interface as a trunk interface to establish a trunk link.
> >
> >
> > On 1/18/06, Gary Ring <garyring.work@gmail.com > wrote:
> > > Man you guys are fast. :-)
> > >
> > > Gary Ring
> > >
> > > On 1/18/06, Gary Ring <garyring.work@gmail.com> wrote:
> > > >
> > > > T.J.
> > > >
> > > > First you have to answer the question, "What is DTP and what is
> > > > it
> used
> > > > for?"
> > > >
> > > > The Cisco answer: Dynamic Trunking Protocol (DTP) for
> > > > negotiating trunking on a link between two devices and for
> > > > negotiating the type
of
> > > > trunking encapsulation (802.1Q or ISL) to be used
> > > >
> > > > That being said. You must specify the type of encapsulation you
want
> to
> > > > use on the trunk link (dot1q or isl). Then, you must issue the
> command
> > > > switchport mode trunk. This sets the port to a trunk
unconditionally
> and
> > > it
> > > > will no longer use DTP frames to try to negotiate becoming a
> > > > trunk
nor
> will
> > > > it listen for DTP frames.
> > > >
> > > > Gary
> > > >
> > > > On 1/18/06, T.J. Mitchell <tj.mitchell@verizon.net> wrote:
> > > > >
> > > > > Guys -
> > > > >
> > > > > How would you disable DTP on the 3550 series switch?
> > > > >
> > > > >
> > > > >
> > > > > Thanks
> > > > >
> > > > >
> > > > >
> > > > > T.J. Mitchell
> > > > >
> > > > >
> ______________________________________________________________________
> _
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> > >
> > >
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