trunking: switchport nonegotiate

Answered Question
Aug 30th, 2009
User Badges:

I read that in order to disable sending DTP frames, we issue "switchport nonegotiate".

But, why do we need it if we already specified that the port is in access or tunk mode already? setting a port to access or trunk disables trunk negotiation, doesn't it?

Correct Answer by Peter Paluch about 7 years 9 months ago

Hi Wassim,


A port statically set to trunk mode still sends DTP packets to inform the other side to also activate the trunk mode. Only a port set to access mode does not send DTP packets.


Best regards,

Peter


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Loading.
Correct Answer
Peter Paluch Sun, 08/30/2009 - 03:01
User Badges:
  • Cisco Employee,

Hi Wassim,


A port statically set to trunk mode still sends DTP packets to inform the other side to also activate the trunk mode. Only a port set to access mode does not send DTP packets.


Best regards,

Peter


Jon Marshall Sun, 08/30/2009 - 04:00
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Peter


Now you've got me confused -


http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Network%20Infrastructure&topic=LAN%2C%20Switching%20and%20Routing&CommCmd=MB%3Fcmd%3Dpass_through%26location%3Doutline%40^1%40%40.2cd45326/0#selected_message


ie. my understanding is non-negotiate stops the port sending DTP frames which is what you put in your previous thread but not this one.


Please help me out :-)


Jon

Peter Paluch Sun, 08/30/2009 - 05:55
User Badges:
  • Cisco Employee,

Hi Jon,


I am sorry if I confused you. Still, I am not sure in what way I have created a confusion. Can you be more specific?


Hoping to read from you soon.


Best regards,

Peter


Jon Marshall Sun, 08/30/2009 - 05:57
User Badges:
  • Super Blue, 32500 points or more
  • Hall of Fame,

    Founding Member

  • Cisco Designated VIP,

    2017 LAN, WAN

Peter


"Only a port set to access mode does not send DTP packets."


A port set to trunk mode ie. "switchport mode trunk" and then set to nonegotiate as well does not send DTP frames.


Jon

Peter Paluch Sun, 08/30/2009 - 06:20
User Badges:
  • Cisco Employee,

Hi Jon,


Oh, yes, that is correct. I was merely replying to the original post context where Wassim asked: "setting a port to access or trunk disables trunk negotiation, doesn't it?" - and I answered only within context of this question. It is true that my answer here is not as exhaustive as my earlier post you have indicated.


Sorry once again for creating confusion, and thanks very much indeed for pointing it up!


Best regards,

Peter


Actions

This Discussion