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Configure Multiple VLANs on single interface

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  • 1.  Configure Multiple VLANs on single interface

    Posted 04-19-2018 02:31

    Hi all,


    I thought I knew how to get the VLANs working on a single interface but for some reason cannot.....


    The scenario is as follows:


    Ethernet Core Connectivity:

    Juniper MX240 Core 1 interface xe-1/1/0

    This interface will be connected to an upstream ISP Ethernet Core where they will supply us VLAN IDs of Ethernet Core customers. 


    BGP Connectivity:

    Juniper MX240 Core 1 interface xe-1/1/4

    This is the interface that the VLANs will access the internet from and is connected to a different Upstream ISP peer.


    I am unsure at the moment if these VLANs will be presented at Layer 2 with no IP Address required on the subinterface or if an IP address will be required.


    1: The best way to configure this single interface?

    2: Can anyone help with the best way to get these VLANs routed to the BGP interface and back?

  • 2.  RE: Configure Multiple VLANs on single interface
    Best Answer

    Posted 04-19-2018 03:06

    The specifics will all depend on where you are doing layer 3 routing with the ISP peers and your customers.


    Any interface can have flexible configuration depending on how the layer 3 and layer 2 are being transported on your setup.


    Do you have a logical and physical diagram to show these releationships?

    Where will you have the layer 3 peer connection to the ISPs?  On this link? on upstream device?  Downstream somewhere?

    How do your customers connect layer 2 and layer 3 to your network?  Are they all on the same or different subnets?


  • 3.  RE: Configure Multiple VLANs on single interface

    Posted 04-19-2018 03:39
      |   view attached

    Hi Spuluka,


    Thank you for your response and here are the answers to your questions....

    Attached is a diagram - You can see the ethernet core labelled and that will enter into the core and then out to either of the ASNs shown (depending on what core from the ethernet core the packet arrives on).


    The two cores will be in separate locations and we may have shadow VLANs but we may not.... decision not made yet as it may be offered as an add on service.


    As I mentioned, we provide customer VLAN details as they join (on the ethernet core)....


    It is explainable on the diagram (I hope)




  • 4.  RE: Configure Multiple VLANs on single interface

    Posted 04-19-2018 03:50

    Add on, I now have the answer that I could not give earlier.


    We will be supplying a device on a customer site and issuing a /30 from our pool we have available. So, it kind of answers my own question now:

    IP Address at customer site, talktalk should just create a .1q trunk to our interface where we will create the subinterfaces with the second available address within that /30 supplied. So, now my quesiton is, do I configure the interfaces as follows:


    set interface xe-1/0/0 vlan tagging

    set interface xe-1/0/0 unit 15 vlan-id 15 family inet address

    set interface xe-1/0/0 unit 30 vlan-id 30 family inet address


    I am expecting, as the core router is a layer 3 device, that it will strip the vlan-id automatically and forward out of the interface for the internet address required....?


    So, I expect the route to be the following:


    Customer --> Core 1 --> DNS --> Core 1 --> customer --> core 1 --> Upstream peer ASN --> Internet





  • 5.  RE: Configure Multiple VLANs on single interface

    Posted 04-20-2018 03:11

    I would configure the interface using flexible vlan tagging:


    encapsulation flexible-ethernet-services;


    This allows the configuration you need today with vlan tags and layer 3 interfaces but would also allow the same interface to have sub interfaces with CCC encapsulation for l2circuits or bridge encapsulation for  layer 2 bridge domains in the future.


  • 6.  RE: Configure Multiple VLANs on single interface

    Posted 04-23-2018 05:31

    Hi spuluka,


    Thank you for the added information. I will configure this and test.... sounds great.... Thank you