Re: Switchport nonegotiate / DTP

From: Mark Lasarko (mlasarko@co.ba.md.us)
Date: Wed Apr 20 2005 - 15:05:33 GMT-3

I agree Dennis,
I rarely see this included in any solutions and wonder why?
 
I don't have the NMC solutions, but of the others I do have I have
only seen this used when DTP is specifically mentioned.

 
Setting the mode to trunk only seems to disable the Access timer.
The Hello timer still runs until you issue 'switchport noneg'
 
Please note that I have not put a sniffer on the port to confirm
DTP packets are actually still being sent as opposed to just
listening?
Can anyone confirm this??

 
************************************************
interface FastEthernet0/48
 switchport trunk encapsulation dot1q
 switchport mode dynamic desirable
!
 
Rack1SW2#
Rack1SW2#sh dtp int fa0/48
DTP information for FastEthernet0/48:
  TOS/TAS/TNS: TRUNK/DESIRABLE/TRUNK
  TOT/TAT/TNT: 802.1Q/802.1Q/802.1Q
  Neighbor address 1: 000000000000
  Neighbor address 2: 000000000000
  Hello timer expiration (sec/state): 8/RUNNING
  Access timer expiration (sec/state): 260/RUNNING
  Negotiation timer expiration (sec/state): never/STOPPED
  Multidrop timer expiration (sec/state): never/STOPPED
  FSM state: S6:TRUNK
  # times multi & trunk 0
  Enabled: yes
  In STP: no
  <statistics omitted>
 
Rack1SW2#config t
Enter configuration commands, one per line. End with CNTL/Z.
Rack1SW2(config)#int fa0/48
Rack1SW2(config-if)#switchport trunk encap dot1q
Rack1SW2(config-if)#switchport mode trunk
Rack1SW2(config-if)#end
Rack1SW2#sh dtp int fa0/48
DTP information for FastEthernet0/48:
  TOS/TAS/TNS: TRUNK/ON/TRUNK
  TOT/TAT/TNT: 802.1Q/802.1Q/802.1Q
  Neighbor address 1: 000000000000
  Neighbor address 2: 000000000000
  Hello timer expiration (sec/state): 20/RUNNING
  Access timer expiration (sec/state): never/STOPPED
  Negotiation timer expiration (sec/state): never/STOPPED
  Multidrop timer expiration (sec/state): never/STOPPED
  FSM state: S6:TRUNK
  # times multi & trunk 0
  Enabled: yes
  In STP: no
  <statistics omitted>
 
Rack1SW2#config t
Enter configuration commands, one per line. End with CNTL/Z.
Rack1SW2(config)#int fa0/48
Rack1SW2(config-if)#switchport noneg
Rack1SW2(config-if)#end
Rack1SW2#sh dtp int fa0/48
1w6d: %SYS-5-CONFIG_I: Configured from console by console
Rack1SW2#sh dtp int fa0/48
DTP information for FastEthernet0/48:
  TOS/TAS/TNS: TRUNK/NONEGOTIATE/TRUNK
  TOT/TAT/TNT: 802.1Q/802.1Q/802.1Q
  Neighbor address 1: 000000000000
  Neighbor address 2: 000000000000
  Hello timer expiration (sec/state): never/STOPPED
  Access timer expiration (sec/state): never/STOPPED
  Negotiation timer expiration (sec/state): never/STOPPED
  Multidrop timer expiration (sec/state): never/STOPPED
  FSM state: S6:TRUNK
  # times multi & trunk 0
  Enabled: yes
  In STP: no
  <statistics omitted>
 
Personally, I don't care for *any* excess traffic, therefore it
would seem like a best practice to me, for the lab or otherwise.
~M
  
>>> "Dennis J. Hartmann" <dennisjhartmann@hotmail.com> 4/20/2005
1:13:44 PM >>>

    If I'm required to statically set all trunk ports to dot1q, I'll
be
turning off DTP with the switchport nonegotiate command.

    I didn't notice this in the NMC solutions. Any ideas?

Sincerely,

Dennis J. Hartmann

White Pine Communications

dh8@pobox.com

CCSI#23402/CCIP/CCNP/CCDP/CCNA/CCDA

Cisco IP Voice Support & Design Specialist

Cisco Optical, VPN & IDS Specialist

MCSE

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