C1300 Multicast Issues

[troyravelo32]

Hello Everyone,

I have some questions regarding the C1300 series switches. I understand these are designed to be SOHO switches, but our intended use for many locations has been to use them for IPTV systems. The number of switches being used is different at each location, but we typically have a single 24XS as our core, designed as a star topology we connect a number of either 8,24, or 48MGP's throughout the physical locations. Our typical setup is 24XS: Snooping globally, Quierier Globally. Snooping per vlan off, Quierier per vlan off. Jumbo packets on, immediate leave on. Our MGP switches are set to Snooping enabled globally and on primary vlan. Note, we only use a single VLAN with tag ID 2, and VLAN 1 is disabled. We also have a netgate 2100 firewall that we use as our DHCP server and gateway that has different rules depending on the site, but no snooping or quierier. Now, what's baffling to me is this exact setup works PERFECT at one of our locations, while at other locations it seems to be intermitent. From a bandwidth spec standpoint, this should work. But, im wondering if anyone has any input on why Multicast seems to struggle on these switches.

[sidshas03]

Hello, I understand your concern regarding multicast issues on the C1300 series switches. These switches are indeed entry-level and not fully optimized for advanced multicast behavior like enterprise Catalyst switches, but they should still handle IPTV streaming reliably with the right configuration. From what you described, your setup is pretty consistent, Snooping enabled globally and on the primary VLAN, with Querier enabled only globally, and immediate-leave turned on. One key point to check is that if you’ve disabled VLAN 1, but some of the switch multicast control logic or querier defaults rely on VLAN 1, it might be causing inconsistencies—especially if the switches fall back to VLAN 1 for IGMP queries. I would recommend testing by temporarily enabling VLAN 1 and assigning an IP address to it on one of the affected switches to see if it stabilizes things. Also, verify that the IGMP Querier is working correctly by checking with the command:

show ip igmp snooping querier

and confirm it’s active on the VLAN carrying your multicast traffic (in your case, VLAN 2). If there's no active querier in that VLAN, multicast membership tables won’t be maintained correctly, and streams may drop intermittently. On the firewall side, make sure it’s not blocking multicast routing or IGMP packets even if it's just acting as DHCP. If needed, enable snooping debug with:

debug ip igmp snooping

to check how the switch handles multicast group joins and leaves. Also, consider disabling immediate-leave temporarily to see if it improves behavior—it can sometimes cause issues in topologies where multicast clients don’t cleanly leave groups. One final suggestion, if you have one site where everything works perfectly, compare firmware versions. Even minor differences in switch firmware across sites can affect IGMP behavior on these platforms. Let me know what model of Netgate firewall you're using and what firmware your C1300 switches are on that could give more clues.

[troyravelo32]

Hello,

Thank you for the insight! I have tried enabling VLAN 1, and granted this will be our common practice moving forward. However, contrary to typical practical network installs, having VLAN 1 didnt really help. The tough part about these switches is the command table isn't the same so the show ip igmp snooping quierier command doesnt exist. With regards to activating the querier on VLAN 2, that actually has often made things worse. The reason being that I noticed, is in order for the querier to be "operational" on this switch, the snooping also has to be active on the VLAN. However, when snooping is active on VLAN 2 (regardless of if its active globally or not), it cause more flooding. I have tried turning off immediate-leave, and it did not remedy the situation and honestly we in a way need immediate leave on for the TV's to pick up quickly. One thing I should note, is we use a device called a COM3000 and this device has a minimum 23 multicast streams constantly being sent out on a single card (up to 6 cards). So I wonder if maybe the C1300's are struggling to manage that level of multicast delegation? I am positive every location has the same (latest) firmware available and the model of the Netgate is the 2100. I am at a loss, I am still relatively fresh in the network engineering world, but I am pretty sure I have tried just about everything these switches can do to rectify. Maybe you have other thoughts on this?

Also, we use an IP audio system within these infrastructures as well. I don't think that should affect the IPTV side of things considering they run off unicast and broadcast, but maybe this information helps. The system is Q-Sys/Dante.