Switchport nonegotiate

Greenmet29

I'm starting to read my icnd2 book by wendell odem, and I got very confused because I kept reading "switchport negotiate" rather than "switchport nonegotiate".

In the part that it talks about what cisco recommends for protecing unused switchports, it says to prevent trunking from being negotiated by using switchport nonegotiate.

When I was reading it incorrectly, I thought, "Why would you make it say negotiate rather than using 'no switchport negotiate'".

This is probably a pretty pointless thread, but it was confusing me for a little while and I don't have my switches in front of me to test the "no switchport negotiate" command... is this a real command or did the software developers at cisco pull a fast one on us?

docrice

There is no no switchport negotiate command. You can do no switchport nonegotiate for sure. I think the word nonegotiate looks weird after you stare at it for a while. It's also one of those double-negative things where you should not undo things where it's bad to reverse the ... oh, crap, there I go again.

Here's a quick article I wrote on DTP and the packet contents:

http://www.kimiushida.com/bitsandpieces/articles/packet_analysis_dtp/

impz

lols decided to lab that up on my switch. Here the output if anyone's interested. [ from left to right ].

Apparently if the "switchport mode" on any interface is set to dynamic, you cant use the "switchport nonegotiate" command so i decided to change port 48 to trunk mode then proceed to use the "switchport nonegotiate".

After I did that, I connected my 2950 to the 3550 ( at port 48 ) and sure enough the port light on my 2950 that was connected to the 3550 was amber while port 48 on the 3550 was green.

Great learning experience. Now back to the VTP labs.

Greenmet29

docrice wrote: »

There is no no switchport negotiate command. You can do no switchport nonegotiate for sure. I think the word nonegotiate looks weird after you stare at it for a while. It's also one of those double-negative things where you should not undo things where it's bad to reverse the ... oh, crap, there I go again.

Here's a quick article I wrote on DTP and the packet contents:

Bits&Pieces: Cisco Dynamic Trunking Protocol (DTP)

Thanks for this post... i've just spent the last hour skimming over your web page... I like the setup of it a lot. I've been thinking about setting up my own web page, and this is a good motivator

Greenmet29

Thanks impz... i'm going to play around with it tomorrow too, I just hate having to wait to find out the answers to my questions!

APA

impz wrote: »

lols decided to lab that up on my switch. Here the output if anyone's interested. [ from left to right ].

Apparently if the "switchport mode" on any interface is set to dynamic, you cant use the "switchport nonegotiate" command so i decided to change port 48 to trunk mode then proceed to use the "switchport nonegotiate".

Yep that's correct... as when the switchport mode is 'dynamic' that is saying.... I want you to use DTP [Dynamic Trunking Protocol] to attempt to negotiate a trunk....

So it would be pointless to let you disable DTP on a switchport in 'dynamic' mode...

Be aware that the port doesn't haven't to be a static 'trunk' to use 'switchport nonegotiate'.... an access port can still use DTP.... it just reports that it is only operating as an Access port.... therefore it's advised to disable DTP on 'switchport mode access' ports as well, as it is clearly unnecessary....