Multicast flood

RouterOS General
1

Hi
I have a HDMI over IP device that I’m trying to use to have a remote monitor on a camera system. The setup is fairly simple:
[ HDMI TX ] ← 100mb → [ Mikrotik Sw ] ← 1gb fiber → [ Mikrotik Sw ] ← 100mb → [ HDMI RX ]
Today I noticed that all Muticast traffic is flooding to all port, IGMP Snooping has enabled.
Is there anyway can I prevent Muticast flooding traffic on Mik.
Thanks

2

For snooping to work properly, you need an IGMP querier. Do you have one configured?

3

Hi can you give me the example how to configure it ?

4

On newer version of RouterOS, there is a tab now under Bridge → Bridge:

https://wiki.mikrotik.com/wiki/Manual:Interface/Bridge#IGMP_Snooping

5

I have enabled IGMP snooping on bridge before I wrote this post. Is there anything else you would like to recommend.

6

Unicast.

7

K6ccc could you please explain more.

8

Run your HDMI over Ethernet in Unicast rather than multicast - provided that the hardware is capable of that. Solves your multicast flood if it’s not running multicast..

9

Or try to configure IGMP Snooping properly? https://help.mikrotik.com/docs/pages/viewpage.action?pageId=59277403
idk.

10

Yes, you did say that you enabled snooping; that was clear. But that does not mean you enabled the querier functionality. I would recommend that you enable this if you have not already. Looks like the requisite option is:


multicast-querier (yes | no; Default: no)	

Multicast querier generates IGMP general membership queries to which all IGMP capable devices respond with an IGMP membership report, usually a PIM (multicast) router or IGMP proxy generates these queries. When RouterOS IPv6 package is enabled, the bridge will also generate MLD general membership queries. By using this property you can make an IGMP Snooping enabled bridge to generate IGMP/MLD general membership queries. This property should be used whenever there is no active querier (PIM router or IGMP proxy) in a Layer2 network. Without a multicast querier in a Layer2 network, the Multicast Database (MDB) is not being updated and IGMP Snooping will not function properly. Only untagged IGMP/MLD general membership queries are generated. This property only has an effect when igmp-snooping is set to yes. Additionally, the igmp-snooping should be disabled/enabled after changing multicast-querier property.[/quote]

If the problem persists after this is configured, a packet capture would be a big help so the query and report functionality can be reviewed.

12

Hi
Znevna, Robertkjonesjr
Following your recommendation I have enabled multicast querier on switch which directly connect to our HDMI Tx, but feel like it do not solve the issue.

/interface bridge
add igmp-snooping=yes multicast-querier=yes name=bridge1 vlan-filtering=yes

For packet capture, does mikrotik support any tools for that?

13

Comparing your first and last screenshots… not exactly sure what you are showing but it looks to me like it was cleaned up a lot. Prior, you have high bandwdith, roughly the same, on each interface. Now only one. But I may be missing something so please help and describe what isn’t looking right from your point of view.

14

Hi robertkjonesjr
I have many switches in my network, the first picture is the traffic captured on my core switch CRS317, the last picture is on switch connected directly to HDMI Tx . As you can see all the traffic still flood to all port in the same VLAN (30). Using Torch tool I see traffic from 172.16.30.22 (my HDMI Tx ip) to 226.2.2.2 (Multicast ip).