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14241 Views 10 Replies Latest reply: Dec 23, 2014 5:45 AM by Jon Major RSS

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Addition of a Vlan in port channel

May 24, 2011 8:00 AM

Paul George 15 posts since
May 22, 2011

Dear Mates,

            I have a case where i need to trunk a vlan through port channel .The set up is like there are two gig interfaces grouped as etherchannel and going to the device . There is confusion in adding the trunk as its very critical if the logical link breaks off. Guys please help me in th is regards.

 

Regards,

 

  • CiscoLoco - CCNP 1,314 posts since
    Feb 11, 2009
    Currently Being Moderated
    1. May 24, 2011 8:35 AM (in response to Paul George)
    Re: Addition of a Vlan in port channel

    Just add "switchport trunk allowed vlan add (vlan tag)" under the port-channel interface. The same vlan changes will be added automatically to all physical interfaces that are part of the port channel.

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  • Currently Being Moderated
    2. May 24, 2011 8:38 AM (in response to Paul George)
    Re: Addition of a Vlan in port channel

    Do the far-end first, and then the near end, and use the command posted above.  Problem solved.

     

    If you have redundant uplinks, be sure you are not changing the path you actually used to login to the device!!

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  • Bourbon, CCNP, CCIE Candidate 177 posts since
    Dec 11, 2008
    Currently Being Moderated
    3. May 24, 2011 8:40 AM (in response to Paul George)
    Re: Addition of a Vlan in port channel

    If you don't already have any "allowed" or disallow commands on the port channel - then the vlan is already flowing through the trunk (unless you're pruning).

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  • Inder Vaid 156 posts since
    Jun 29, 2009
    Currently Being Moderated
    5. May 25, 2011 7:44 AM (in response to Paul George)
    Re: Addition of a Vlan in port channel

    You can add one pair of link to etherchannel and if you are running STP like RSTP, then you can shutdown the link which is not on etherchannel, it will shift traffic within sub-millisecond to channel group link, then you can add the ports which were shutdown to etherchannel.

    I did this on a link passing 1 gig channel without any single ping loss.

     

    HTH

    Inder Vaid

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  • Inder Vaid 156 posts since
    Jun 29, 2009
    Currently Being Moderated
    7. May 29, 2011 2:10 AM (in response to Paul George)
    Re: Addition of a Vlan in port channel

    I am not sure about the command but if the etherchannel config is not matching on both ends or say between 2 physical interfaces on same router which you are adding in etherchannel, then etherchannel will not come up.

    So have to be very careful when doing this on live traffic in business hours, in maintenance time that is least concerned but still

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  • mostapha 1 posts since
    Nov 17, 2014
    Currently Being Moderated
    9. Dec 23, 2014 1:23 AM (in response to Paul George)
    Re: Addition of a Vlan in port channel

    hi

    i have a quisten according to the above

    i configure allowed valn per interface physical on one swicth and i configure the other one per port-channel interface

     

     

    and i notice the diffrent as the below althoug the same vlan allowed are used why are the active and prune valn are diffrent

    Switch#show int trun

    Port        Mode         Encapsulation  Status        Native vlan

    Fa0/4       on           802.1q         trunking      1

    Fa0/5       on           802.1q         trunking      1

     

    Port        Vlans allowed on trunk

    Fa0/4       20-30,50

    Fa0/5       20-30,50

     

    Port        Vlans allowed and active in management domain

    Fa0/4       20,30,50

    Fa0/5       20,30,50

     

    Port        Vlans in spanning tree forwarding state and not pruned

    Fa0/4       20,30,50

    Fa0/5       20,30,50

    Switch#

     

    ------------------------------------------------------------------------

     

     

    trunk feature activate per ether-channel

     

    Switch#show int trun

    Port        Mode         Encapsulation  Status        Native vlan

    Fa0/4       on           802.1q         trunking      1

    Fa0/5       on           802.1q         trunking      1

     

    Port        Vlans allowed on trunk

    Fa0/4       1-1005

    Fa0/5       1-1005

     

    Port        Vlans allowed and active in management domain

    Fa0/4       1,20,30,40,50

    Fa0/5       1,20,30,40,50

     

    Port        Vlans in spanning tree forwarding state and not pruned

    Fa0/4       1,20,30,40,50

    Fa0/5       none

     

     

    s

     

     

    Switch#show int trun
    Port        Mode         Encapsulation  Status        Native vlan
    Fa0/4       on           802.1q         trunking      1
    Fa0/5       on           802.1q         trunking      1
    Port        Vlans allowed on trunk
    Fa0/4       20-30,50
    Fa0/5       20-30,50
    Port        Vlans allowed and active in management domain
    Fa0/4       20,30,50
    Fa0/5       20,30,50
    Port        Vlans in spanning tree forwarding state and not pruned
    Fa0/4       20,30,50
    Fa0/5       20,30,50
    Switch#
    ------------------------------------------------------------------------
    trunk feature activate per ether-channel
    Switch#show int trun
    Port        Mode         Encapsulation  Status        Native vlan
    Fa0/4       on           802.1q         trunking      1
    Fa0/5       on           802.1q         trunking      1
    Port        Vlans allowed on trunk
    Fa0/4       1-1005
    Fa0/5       1-1005
    Port        Vlans allowed and active in management domain
    Fa0/4       1,20,30,40,50
    Fa0/5       1,20,30,40,50
    Port        Vlans in spanning tree forwarding state and not pruned
    Fa0/4       1,20,30,40,50
    Fa0/5       none
    s

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  • Jon Major 33 posts since
    Feb 22, 2009
    Currently Being Moderated
    10. Dec 23, 2014 5:45 AM (in response to mostapha)
    Re: Addition of a Vlan in port channel

    mostapha,

     

         Your etherchannel is not active, so on the bottom switch your manual pruning isn't taking effect. I'm guessing you're using pagp or lacp to negotiate the etherchannel. If you apply 'switchport trunk allowed vlan x,y,z' on a port channel interface, that port channel interface has to actually be up in order for the configurations to take effect. Secondly, the "vlans in spanning-tree forwarding state' section, looks like on the bottom switch Fa0/4 is the root port and Fa0/5 is in blocking state.

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