I just tested this in Lab
Two Routers , Router A and Router B
Router A has switchport mode access
Router B has switchport mode dynamic desirable.
Router A doesnot send DTP frames , Router B does send DTP frames
But the debug on Router A doesnot show that it is receiving periodic frames may
be it is ignoring.
Strangely if you change the mode on Router A to dynamic auto DTP frames are
send and received. But once the mode
is changed to access a single DTP frames is shown as received and send and then
no DTP activity on Router A.
But the debug shows that Router B is sending periodic frames.
Can anybody else confirm this behaviour
debug dtp events and debug dtp packets
Regards
Zeeshan
From: [email protected]
To: [email protected]; [email protected]; [email protected];
[email protected]; [email protected]
Subject: RE: [OSL | CCIE_RS] Disabling DTP Negotiation
Date: Mon, 6 Jul 2009 19:37:48 -0500
This may all be word play, but the way I
look at it the “D” in DTP is for Dynamic. To Jared’s point “Switchport
nonegotiate”
states that it disables DTP frames so it is turning DTP off just like Jared
stated. Now lets
look at switchport mode access. Based on the chart below it “negotiates
to convert the link into a nontrunk link” Key word
“Negotiates” or in other words uses a protocol. An option for DTP could be not
to create
a trunk. If that is the case DTP is
still operating to prevent a trunk from being created. When all is said and
done Switchport nonegotiate is the only
one that states you need to configure manually with no negotiations happening.
That’s my 2 cents for what it is
worth.
Rob.
From:
[email protected]
[mailto:[email protected]] On
Behalf Of prakash patel
Sent: Monday, July 06, 2009 2:32
PM
To: [email protected];
[email protected]; [email protected];
[email protected]
Subject: Re: [OSL | CCIE_RS]
Disabling DTP Negotiation
switchport
mode access
Puts the
interface (access port) into permanent nontrunking mode and negotiates to
convert the link into a nontrunk link. The interface becomes a nontrunk
interface regardless of whether or not the neighboring interface is a trunk
interface.
switchport
mode dynamic auto
Makes the interface able to convert the link to a
trunk link. The interface becomes a trunk interface if the neighboring
interface is set to trunk
or desirable mode. The
default switchport mode for all Ethernet interfaces is dynamic auto.
switchport
mode dynamic desirable
Makes the interface actively attempt to convert the
link to a trunk link. The interface becomes a trunk interface if the
neighboring interface is set to trunk,
desirable, or auto mode.
switchport
mode trunk
Puts the interface into permanent trunking mode and
negotiates to convert the neighboring link into a trunk link. The interface
becomes a trunk interface even if the neighboring interface is not a trunk
interface.
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.
From: [email protected]
To: [email protected]; [email protected];
[email protected]
Date: Mon, 6 Jul 2009 15:19:17 -0400
Subject: Re: [OSL | CCIE_RS] Disabling DTP Negotiation
Sorry Jared,
Correct me if I am wrong but
it is not like switchport mode access
will disable DTP and will never form a trunk, regardless
of configuration on the other end of the link. And switchport
nonegotiate will disable DTP and will form a turnk if both the ends are
configured
with switchport mode trunk.
Thanks,
Haresh
From: [email protected]
To: [email protected]; [email protected]
Date: Mon, 6 Jul 2009 12:56:48 -0400
Subject: Re: [OSL | CCIE_RS] Disabling DTP Negotiation
Nope.
“switchport nonegotiate” disables DTP.
Cheers,
Jared Scrivener CCIE3 #16983 (R&S,
Security, SP), CISSP
Sr. Technical Instructor - IPexpert, Inc.
URL: http://www.IPexpert.com
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: [email protected]
From:
[email protected]
[mailto:[email protected]] On
Behalf Of Zeeshan Sanaullah
Sent: Monday, 6 July 2009 10:29 AM
To: cciers OSL
Subject: [OSL | CCIE_RS] Disabling
DTP Negotiation
Hello Group !!!
Just a quick question ,
will this command disable DTP switchport mode
access
I know switchport nonegotiate disables but what if we just specify
the above will it disable DTP
Regards
Zeeshan
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