switchport mode not changing to desirable

hi ,

i have a basic problem,..wen i practiced vlan trunking in Packet tracer,...i am getting wierd output.

there are two switchs,..sw1 and sw2..when i changed the switchport mode to Dynmaic desrable in sw1, port Gigabit1/1 the output for the command:      

Sh Int Trunk    is

Switch(config)#do sh int tr
Port        Mode         Encapsulation  Status        Native vlan
Gig1/1      auto         n-802.1q       trunking      1

Port        Vlans allowed on trunk
Gig1/1      1-1005

Port        Vlans allowed and active in management domain
Gig1/1      1

Port        Vlans in spanning tree forwarding state and not pruned
Gig1/1      1

its still showing auto mode in the mode column..

where as the admin mode changed and is shown up in the output for the command :

sh int gigabit1/1 sw

Switchport: Enabled
Administrative Mode: dynamic desirable
Operational Mode: trunk
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: On
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Voice VLAN: none
Administrative private-vlan host-association: none
Administrative private-vlan mapping: none
Administrative private-vlan trunk native VLAN: none
Administrative private-vlan trunk encapsulation: dot1q
Administrative private-vlan trunk normal VLANs: none
Administrative private-vlan trunk private VLANs: none
Operational private-vlan: none
Trunking VLANs Enabled: ALL
Pruning VLANs Enabled: 2-1001
Capture Mode Disabled
Capture VLANs Allowed: ALL
Protected: false

and the other switch which is dynamic auto started the negotiation and the admin mode over tat switch is dynamic auto

Some1 plz help me

Comments

  • Could be a packet tracer issue. Have you tried on real equipment? Unfortunately, I don't have PT on this PC, but I will try later on and let you know if I get the same behavior or not.

  • I tried reinstalling the packet tracer but still the same output....

  • Hi!

    I also think it is a packet tracer issue. Just labbed it on real equipment. Here is the show output.

     

    #########################################

    Rack1SW2#sh int trunk

    Port        Mode             Encapsulation  Status        Native vlan
    Fa0/13      auto             n-isl          trunking      1

    Port        Vlans allowed on trunk
    Fa0/13      1-4094

    Port        Vlans allowed and active in management domain
    Fa0/13      1,5,7-10,22,43,50,58-59,67,79,100,146

    Port        Vlans in spanning tree forwarding state and not pruned
    Fa0/13      1,5,7-10,22,43,50,58-59,67,79,100,146
    Rack1SW2#
    Rack1SW2#
    Rack1SW2#conf t
    Enter configuration commands, one per line.  End with CNTL/Z.
    Rack1SW2(config)#int fa0/13
    Rack1SW2(config-if)#switchport trunk enc dot1
    Rack1SW2(config-if)#switchport
    *Mar  1 04:09:46.618: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/13, changed state to down
    *Mar  1 04:09:46.618: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to down
    *Mar  1 04:09:46.618: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan8, changed state to down
    *Mar  1 04:09:46.618: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan58, changed state to down
    Rack1SW2(config-if)#switchport mode dyn
    *Mar  1 04:09:50.670: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/13, changed state to up
    Rack1SW2(config-if)#switchport mode dyn des
    Rack1SW2(config-if)#do sh int trunk

    Port        Mode             Encapsulation  Status        Native vlan
    Fa0/13      desirable        802.1q         trunking      1

    Port        Vlans allowed on trunk
    Fa0/13      1-4094

    Port        Vlans allowed and active in management domain
    Fa0/13      1,5,7-10,22,43,50,58-59,67,79,100,146

    Port        Vlans in spanning tree forwarding state and not pruned
    Fa0/13      none

    ###############################

     

    Are you planning to go on real gear? Are you using dynamips (well switches cannot be simulated in dynamips really good, but for routing its fine!)

     

    Regards!

    Markus

  • i have a basic problem,..wen i practiced vlan trunking in Packet tracer,...i am getting wierd output.

    there are two switchs,..sw1 and sw2..when i changed the switchport mode to Dynmaic desrable in sw1, port Gigabit1/1 the output for the command:      

    Certainly not an issue related to technology itself.

  • I just labbed this up in both Packet Tracer and real hardware and am getting the same results as you are both seeing.

    Packet Tracer:

    Switch#sho in g1/1 sw
    Name: Gig1/1
    Switchport: Enabled
    Administrative Mode: dynamic desirable

    Switch#sho int tru
    Port        Mode         Encapsulation  Status        Native vlan
    Gig1/1      auto         n-802.1q       trunking      1

     

    Real Hardware:

    Rack1SW3#sho int f0/13 sw        
    Name: Fa0/13
    Switchport: Enabled
    Administrative Mode: dynamic desirable
    Operational Mode: trunk

    Rack1SW3#sho int trunk

    Port        Mode             Encapsulation  Status        Native vlan
    Fa0/13      desirable        n-isl          trunking      1

    Seems to be a Packet Tracer issue.

  • Ok thank you every one...

  • Yes- just did on PT as well, same thing. Definitely a bug or something with PT

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