Question about DTP

Garo

Hey everyone, Im studing for the ccent certification, and after finishing the book of Odom Wendell I found out that I don't fully understand this part of DTP, so
what's the meaning of "switchport nonegotiate" command?
Im asking this becouse when I put the "switchport mode access" command and then I issue the "show interfaces switchport" command it says "Negotiation of Trunking: Off"
So my question is, is there any meaning in using the "switchport nonegotiate" command after the "switchport mode acces/trunk"?
Will it still send hello dtp messages after making the interface be a static access/trunk?

Thank you

xnx

Have a look at this

Garo

Thanks xnx, but I didnt mean that..
I was asking, what is the purpose of setting "switchport nonegotiate" to an interface that is already configured with switchport mode trunk or access.

xnx

It stops DTP advertisements from being sent out of that interface, so it won't form a trunk with another interface which is on dynamic desirable.

Garo

Sorry, but I mean...
Is there any sense in issuing the nonegotiate commander if the switchport is already a static access or trunk?

gorebrush

There is a benefit of turning off DTP on static trunks yes.

It adds a small amount of time in bringing up the link up while DTP packets are sent/received. If you know the port will be a trunk, then why spend the time negotiating DTP as well?

Garo

I see..
Thank you gorebrush !

PCHoldmann

If you leave DTP negotiation on a static trunk, it will still try to form a trunk with a port in Auto mode. Nonegotiate will prevent it from trying.

Normally I would say you should know what ports are going to be trunks, statically configure them as such, and turn off DTP. This is less for any time savings, which should be rare and minimal, but for network stability and security. If something should be a trunk, make sure it stays that way. If it should not be a trunk, make sure it can't become one.