Hi everyone, I'm running into an issue with IPTV multicast traffic on a Meraki MS120-48 switch and would really appreciate any insight or advice from the community. Issue Summary: IPTV set-top boxes experience frequent screen freezing when connected through the MS120-48. Only a single multicast stream is tested, yet freezing still occurs. IGMP Snooping is ON, and Unknown Multicast Flood is OFF — this combination works best but doesn’t resolve the issue. All other ports are disconnected during testing (no background traffic, a one receiver and a one sender are connected and only send a one multicast stream from sender) The multicast stream is Full HD (1920x1080), H.264 codec, 6 Mbps fixed bitrate. When analyzing link status, I found that the IPTV set-top box always negotiates at 100 Mbps, while the multicast sender (encoder) negotiates at 1 Gbps on all switches. Interestingly, on the MS120-48, I manually set the encoder port to 100 Mbps, and the freezing issue slightly improved — but it’s still significantly worse than when using a Cisco 9200L or Zyxel 1920G switch. On the Zyxel 1920G and Cisco 9200L switches, even with multiple multicast streams and the same port speeds (1G ↔ 100M), the issue does not occur at all. Questions: Has anyone experienced similar multicast issues with the MS120-48? Is there any known limitation in how the MS120-48 handles multicast internally (e.g., software vs hardware forwarding)? Any QoS, VLAN, or other configuration tweaks that helped in your case? Thanks in advance — any shared experience or tips would be greatly appreciated!
... View more
