Re: DTP - Interpreting the Question

well it doesn't really matter how the trunks are formed as long as the
trunks are formed (i.e. on <--> on or on <--> desirable or on <--> auto or
desirable <--> desirable or desirable <--> auto). the important thing to be
taken from the task is *"SW1's port should be configured statically to have
802.1q trunking. SW2 should negotiate 802.1q as trunking protocol to SW1.
SW1 should not negotiate 802.1q to SW2"* so under the SW1's interface using
'switchport trunk encapsulation dot1q' should be good to get d points for u.
 But to be on the safe side, u can as well just ask the proctor if its
necessary for the forming of the trunk at SW1 should be done statically
using 'switchport mode trunk' just because of this line "SW1's port *should
be configured statically* to have 802.1q trunking"

On Fri, May 20, 2011 at 1:25 PM, Nathan Falcon <nathan.falcon_at_gmail.com>wrote:

> The reason I'm not so sure that desirable would be necessary is that the
> interface is set to negotiate the encapsulation by default. However, you
> may be right. Without adding any extra configuration on top of what the
> question is asking for, the config could be:
>
> SW1(config-if)#do sh run int fa0/24
> Building configuration...
>
> Current configuration : 72 bytes
> !
> interface FastEthernet0/24
> switchport trunk encapsulation dot1q
> end
>
> SW1(config-if)#do sh int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/24 auto 802.1q trunking 1
>
>
> ------------------------------------------------------------------------------------------------------------------------
> SW2(config-if)#do sh run int fa0/24
> Building configuration...
>
> Current configuration : 69 bytes
> !
> interface FastEthernet0/24
> switchport mode dynamic desirable
> end
>
> SW2(config-if)#do sh int trunk
>
> Port Mode Encapsulation Status Native vlan
> Fa0/24 desirable n-802.1q trunking 1
>
>
>
> On Fri, May 20, 2011 at 6:10 AM, Sud Mu <mitsuie2_at_gmail.com> wrote:
>
> > I personally think that i should have "switchport mode dynamic desirable"
> > on SW2 because the question says "SW2 should negotiate 802.1q as trunking
> > protocol to SW1". But definitely i would go to proctor and ask whether
> SW2
> > should initiate DTP negotiation.
> >
> > Sud.
> >
> > On Thu, May 19, 2011 at 6:31 PM, Nathan Falcon <nathan.falcon_at_gmail.com
> >wrote:
> >
> >> Pretty tricky....I'm not so sure I agree here. It seems to me that a
> >> solution that would fail after a reboot or interface reset would be
> >> incorrect.
> >>
> >> Disabling DTP on SW1 would not kill the already negotiated trunk, but if
> >> you shut/no shut the SW2 side it won't come back up. I'm not so sure
> this
> >> question is really looking for DTP to be disabled. It would be
> necessary
> >> for proper functionality. This is how i'm perceiving the solution for
> this
> >> one.
> >>
> >> (This might be a good one to go to the proctor on too....I bet you could
> >> get the answer out of him/her if you choose your words right.)
> >>
> >> SW1
> >> interface FastEthernet0/24
> >> switchport trunk encapsulation dot1q
> >> switchport mode trunk
> >>
> >> SW1#sh int trunk
> >>
> >> Port Mode Encapsulation Status Native vlan
> >> Fa0/24 on 802.1q trunking 1
> >>
> >>
> >>
> >> SW2
> >> interface FastEthernet0/24
> >> (dynamic desirable would work here to, but seems unnecessary)
> >>
> >> SW2#sh int trunk
> >> Port Mode Encapsulation Status Native vlan
> >> Fa0/24 auto n-802.1q trunking 1
> >>
> >> Nate
> >>
> >>
> >>
> >> On Thu, May 19, 2011 at 8:31 AM, Edwin Campbell <
> >> edwin.l.campbell_at_gmail.com> wrote:
> >>
> >>> I agree with Leonardo 100%. If you were going to connect two switches
> via
> >>> a
> >>> trunk link and before you cabled it up, you added the "switchport
> >>> nonegotiate" command, yes, that would stop the trunking protocol
> >>> negotiation.
> >>>
> >>> The only way that the switchport nonegotiate command would not stop a
> >>> trunk
> >>> link from negotiating would be if you added that command after your
> >>> trunks
> >>> have already gone through the negotiation process. Because the
> switches
> >>> have already negotiated which trunking protocol that they're going to
> >>> use,
> >>> adding the "switchport nonegotiate" will not effect anything.
> >>>
> >>> Lab it up =).
> >>>
> >>> Edwin
> >>>
> >>>
> >>>
> >>> On Thu, May 19, 2011 at 4:19 PM, Leonardo Hideki
> >>> <leohideki.ccie_at_gmail.com>wrote:
> >>>
> >>> > Hi Roy,
> >>> >
> >>> > I thought of that also, but disabling DTP wouldn't prevent SW2 from
> >>> > learning
> >>> > which encap type it should use as well?
> >>> >
> >>> > Rgrds,
> >>> >
> >>> > Leonardo Hideki
> >>> >
> >>> >
> >>> >
> >>> > On Thu, May 19, 2011 at 8:36 AM, Roy Khan <roykhan123_at_hotmail.com>
> >>> wrote:
> >>> >
> >>> > >
> >>> > > Hi Guys
> >>> > >
> >>> > > Perfect solution Just I add one more command
> >>> > >
> >>> > > int fax/x
> >>> > > > switchport trunk encap dot1q
> >>> > > > switchport mode trunk
> >>> > > *Switchport Nonegotiate *
> >>> > > when you type show int trunk command on this switch you will see
> Mode
> >>> is
> >>> > > -On- it and Encapsulation means
> >>> > > you statically configure the trunk.
> >>> > > also use *show int Fax/x switchport* command to verify this.
> >>> > > Remember 3560 default mode is switchport dynamic auto.
> >>> > >
> >>> > > Br
> >>> > >
> >>> > > Roy
> >>> > >
> >>> > >
> >>> > > > Date: Thu, 19 May 2011 06:24:37 -0300
> >>> > > > Subject: Re: DTP - Interpreting the Question
> >>> > > > From: leohideki.ccie_at_gmail.come
> >>> > > > To: mitsuie2_at_gmail.com
> >>> > > > CC: ccielab_at_groupstudy.com
> >>> > >
> >>> > > >
> >>> > > > Hi Sud,
> >>> > > >
> >>> > > > As SW1 should not negotiate, you should configure dot1q / trunk
> >>> > > statically:
> >>> > > >
> >>> > > > !
> >>> > > > int fax/x
> >>> > > > switchport trunk encap dot1q
> >>> > > > switchport mode trunk
> >>> > > > !
> >>> > > >
> >>> > > > On SW2, it could be either desirable or auto, since SW1 is
> >>> statically
> >>> > > > configured to trunk.
> >>> > > >
> >>> > > > !
> >>> > > > int fax/x
> >>> > > > switchport mode dynamic [auto | desirable]
> >>> > > > !
> >>> > > >
> >>> > > > In order to check this config, issue a "sh int trunk" on both
> >>> sides. On
> >>> > > > switch 1, it should come up with "802.1q" while on switch 2, it
> >>> should
> >>> > > come
> >>> > > > up with "n-802.1q", "n" meaning that the trunking protocol was
> >>> > > negotiated.
> >>> > > >
> >>> > > > HTH.
> >>> > > >
> >>> > > > Rgrds,
> >>> > > >
> >>> > > > Leonardo Hideki
> >>> > > >
> >>> > > > On Mon, May 16, 2011 at 4:28 AM, Sud Mu <mitsuie2_at_gmail.com>
> >>> wrote:
> >>> > > >
> >>> > > > > Hi All,
> >>> > > > >
> >>> > > > > I've got a problem in interpreting this DTP question
> >>> > > > >
> >>> > > > > If there was a question where SW1 and SW2 are directly
> connected.
> >>> > > > >
> >>> > > > > Question:
> >>> > > > > =======
> >>> > > > > Link between SW1 and SW2 should be a 802.1q trunk. SW1's port
> >>> should
> >>> > be
> >>> > > > > configured statically to have 802.1q trunking. SW2 should
> >>> negotiate
> >>> > > 802.1q
> >>> > > > > as trunking protocol to SW1. SW1 should not negotiate 802.1q to
> >>> SW2.
> >>> > > > >
> >>> > > > > Where should I put "switchport mode dynamic desirable" ? on SW1
> >>> or
> >>> > SW2
> >>> > > ?
> >>> > > > >
> >>> > > > > Although simple please give you experts idea
> >>> > > > >
> >>> > > > > Thanks,
> >>> > > > > Sud
> >>> > > > >
> >>> > > > >
> >>> > > > > Blogs and organic groups at http://www.ccie.net
> >>> > > > >
> >>> > > > >
> >>> >
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Received on Fri May 20 2011 - 14:36:39 ART