Tagged VLAN on one port to untagged on another

Hi all,

I have a situation where I have an uplink port that has internet untagged (also bridged, since I have a modem inbetween) and VLAN ID 3999 for IPTV.
I have some client devices that support the VLAN tag and those are just set the uplink port as the master port and it works.
But I also have an STB that requires the stuff on VLAN 3999 to be untagged (and also no internet).
Would that be possible to do on a CSR125-24G-1S?

Example
Eth1: native internet, 3999 IPTV
Eth2: native internet, 3999 IPTV (master port set to Eth1)
Eth3: native IPTV only

Thanks

Yes, just have to have vlan 3999 in the vlan table for ether3 (and 1 & 2), but not in the egress-vlan-tag table for port 3, just port 1 & 2.

wouldnt that keep the traffic tagged?

The CRS switch chip only tags traffic for vlans if in the egress-vlan-tag table, otherwise it will strip the tag.

The VLAN table controls what VLANS are allowed on what ports.

So if you have a port in the VLAN table, but not the egress-vlan-tag table, it’s allowed on the port, but stripped.

Normally if you strip the tag, you would also want to set a default vlan in the ingress-vlan-translation table. But probably unnecessary in an IPTV setup.