IGMP snooping with VLAN filtering: only one querier/multicast router seen per bridge?

RouterOS General
1

Hi,

I have a problem with IGMP snooping on a bridge with several VLANs, and I'd like to understand if this is a limitation or a misconfiguration.

Setup

  • MikroTik CCR2116, RouterOS 7.24.2
  • One bridge BRIDGE with vlan-filtering=yes, igmp-snooping=yes, multicast-querier=no, igmp-version=2
  • 4 SFP+ ports, all tagged members of VLANs 10–130, with Aruba switches behind them
  • All bridge ports use multicast-router=temporary-query
  • Topology: switch1 → switch2 → CCR → switch3
  • External IGMP queriers (the Aruba switches, one per VLAN): VLAN 30 → 10.30.1.253, VLAN 110 → 10.110.1.253. The CCR is not a querier.
  • The location of the VLAN 110 querier can change (it depends on where the customer plugs their equipment), so I can't hardcode a port.

Problem

  • The same multicast stream sent from switch1 on VLAN 30 works end to end, including through the CCR to switch3, first try.
  • On VLAN 110, it works from switch1 to switch2, but not on switch3 (behind the CCR).
  • I also tried making VLAN 110 untagged on ether5 of the CCR: same result.

What I see on the CCR

  • The Status tab of the bridge interface shows only one querier: IGMP Querier: sfp-sfpplus2 10.30.1.253 (VLAN 30). The VLAN 110 querier (10.110.1.253) is clearly visible from the Aruba switches but never shows on the CCR.
  • /interface bridge mdb print shows VLAN 110 groups learned (reports are received, only on sfp-sfpplus4), so snooping itself works per VLAN.
  • /interface bridge vlan print detail shows VLAN 110 tagged on the bridge and on all 4 SFP+ ports.

My assumptions (not verified)

  1. The bridge tracks one multicast router port / external querier for the whole bridge, not one per VLAN. So reports of VLAN 110 are only forwarded towards the VLAN 30 router port (sfp-sfpplus2).
  2. Since the bridge querier only sends untagged queries from 0.0.0.0, enabling multicast-querier=yes doesn't seem useful here (and an external querier is already detected).

Questions

  1. Is the multicast router port / querier detection per bridge or per VLAN in RouterOS 7 when VLAN filtering is enabled? Is it documented anywhere?
  2. Is setting multicast-router=permanent on all trunk ports a reasonable workaround when queriers are on different VLANs and their location can move? What are the downsides?
  3. Is there a better design (for example separate bridges, or IGMP proxy with VLAN interfaces) for several multicast VLANs with external queriers?

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Thanks!

2

IGMP queriers should be per-VLAN. Multicast across VLANs calls for PIM.

3

Yes, agreed. But this is not multicast routing between VLANs.

I have two independent multicast VLANs, VLAN 30 and VLAN 110, on the same VLAN-aware bridge. Both have their own IGMP querier and IGMP snooping is enabled.

VLAN 30 works correctly, but VLAN 110 is flooded.

So my question is simply: can RouterOS 7.24 handle IGMP snooping independently for multiple VLANs on the same bridge, with separate MDBs per VLAN?

4

Hello,

I found a workaround for my issue: I configured all four SFP interfaces on my CCR with multicast-router = permanent.

With multicast-router = temporary-query, the CCR was not detecting the IGMP querier from my client.

The querier on the client side is a MikroTik. It is correctly detected by all my HP 2530 switches on VLAN 110, but not by my CCR.

Here is the client's configuration:

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Do you have any idea why the IGMP querier is detected correctly by the HP switches but not by the CCR?

Is there anything specific in this MikroTik configuration that could explain why the CCR does not detect it when using temporary-query?

Thanks for your help.