[j-nsp] JunOS 18, ELS vs non-ELS QinQ native vlan handling.

[Andrey Kostin]

Hi Alexandre,

Did it pass frames without C-tag in Junos versions < 18?

Kind regards,
Andrey

Alexandre Snarskii писал 2019-03-22 13:03:
> Hi!
> 
> Looks like JunOS 18.something introduced an incompatibility of native
> vlan handling in QinQ scenario between ELS (qfx, ex2300) and non-ELS
> switches: when ELS switch forwards untagged frame to QinQ, it now adds
> two vlan tags (one specified as native for interface and S-vlan) 
> instead
> of just S-vlan as it is done by both non-ELS and 'older versions'.
> 
> As a result, if the other end of tunnel is non-ELS (or third-party)
> switch, it strips only S-vlan and originally untagged frame is passed
> with vlan tag :(
> 
> Are there any way to disable this additional tag insertion ?
> 
> PS: when frames sent in reverse direction, non-ELS switch adds only
> S-vlan and this frame correctly decapsulated and sent untagged.
> 
> ELS-side configuration (ex2300, 18.3R1-S1.4. also tested with
> qfx5100/5110):
> 
> [edit interfaces ge-0/0/0]
> flexible-vlan-tagging;
> native-vlan-id 1;
> mtu 9216;
> encapsulation extended-vlan-bridge;
> unit 0 {
>     vlan-id-list 1-4094;
>     input-vlan-map push;
>     output-vlan-map pop;
> }
> 
> (when native-vlan-id is not configured, untagged frames are not
> accepted at all).
> 
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