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vlan-tagging required for trunk port?

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  • 1.  vlan-tagging required for trunk port?

    Posted 02-15-2018 11:41

    I am setting up an EX4600/4300 virtual chassis to replace an existing cisco core stack. 


    I have configured several aggregate ports  and have set the unit 0 interface-mode to trunk.  I notice that there is also an option to set vlan-tagging on the interface such as: set interface ae0 vlan-tagging.  I am not sure if this is required though.  I am not using subinterfaces.


    On the current cisco switches I am used to having to set "switchport trunk encapsulation dot1q" so coming from cisco I wonder if an equivalent command is needed on the juniper (ie vlan-tagging)?


    Also, worth mentioning, is access switches are still Cisco. Are there other considerations for interoperability with cisco/juniper trunking? The config on all Ciscos is quite basic. Example:

    interface Port-channel1
    description Link to CoreStack
    switchport trunk encapsulation dot1q
    switchport trunk allowed vlan 1-10,100,102
    switchport mode trunk
    switchport nonegotiate



  • 2.  RE: vlan-tagging required for trunk port?
    Best Answer

    Posted 02-15-2018 15:28

    No, in this case 'vlan-tagging' is not required.  That setting allows the use of tagged subinterfaces.  I think you should get a commit error if you try to configure 'vlan-tagging' on an interface set for family ethernet-switching.


    Juniper only supports 802.1Q trunks, so there isn't a setting similar to the Cisco 'encapsulation dot1q'.  You will have to configure the vlans allowed on the Juniper side of the trunk (Juniper default is none allowed), and make sure the vlans are defined under the 'vlans' stanza.  But other than that you should be set.

  • 3.  RE: vlan-tagging required for trunk port?

    Posted 02-15-2018 15:57

    Ok thats what I was thinking.  No subinterfaces in use so vlan-tagging not required. thanks