Hello.

 

I have quite a simple multicast setup where I have an ONT plugged to a switch (port 1). It is providing a tagged vlan 203 for an iptv settop box. The iptv setop box is plugged to port 2 of the switch using an untagged vlan 203 port. The iptv settop box receives an IP via DHCP and then tries to request multicast groups.

 

Assuming the switch is factory defaulted, these are the steps I do to configure it:

 

In L2 Features -> VLANS I add VLAN 203 and set port 1 as tagged, and port 2 as untagged.

 

 

In L2 Features -> VLANS -> Port Config I set port 2 PVID of 203:

 

 

 

For completeness sake, I also enable IGMP Snooping but it's actually irrelevant to this problem (it can remain disabled).

 

 

With the above config, the iptv setop box receives a DHCP address, Multicast IP Address Table is filled in the switch, but IGMP messages are not forwarded outside the switch.

 

It starts working if I set the PVID of port 1 to 203 which to my mind is confusing.

 

 

Why would I need to set a PVID of the tagged port? It's as if the switch is stripping multicast traffic of a vlan tag when in enters the switch.

 

For comparison, I had plugged a d-link switch instead of tplink which has the same simple configuration (just vlan 203 tag port 1 and untag vlan 203 port 2) and it works:

 

 

To me it seems to be some kind of a bug, why do I need to set PVID 203 to PORT 1 for igmp messages to be forwarded outside the switch?

The same behaviour happens on TLSG2210MP ( TL-SG2210MP(UN)_V3_3.0.5 Build 20221130 )  (the setup won't work unless I set pvid 203 for port 1).