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Forum Discussion
M4100-26G-POE Multicast router
Hello,
For a system with AV streaming on a network, I'm looking for a way to prohibit a 3rd party router to become the IGMP querier automatically through election. See the network topology attached.
The M4100 switch has multiple AV en- and decoders connected with a datarate of 1Gbit/s. I would like this switch to be the IGMP Querier but due to the automatic election between the switch and the 3rd party router, the 3rd party router becomes the querier.
As the 3rd party router becomes the querier, all 1Gbit streams of the AV encoders are congesting the link between the router and the switch.
Some extra info:
- IGMP snooping is enabled.
- There's no IGMP router port configured.
- Firmware: 10.0.2.30
Is there a command or configuration I can use to achieve this?
Thank you.
Regards,
Kevin
3 Replies
Hello Kevin,
KevinHu wrote:The M4100 switch has multiple AV en- and decoders connected with a datarate of 1Gbit/s. I would like this switch to be the IGMP Querier but due to the automatic election between the switch and the 3rd party router, the 3rd party router becomes the querier.
The router or switch that is configured to act as the IGMP Querier is the master of the IGMP filter lists is the network only. The ICMP Querier responsibility is to send out IGMP group membership queries on a timed interval, to retrieve IGMP membership reports from active members, and to allow updating of the group membership tables. Nothing more, nothing less.
KevinHu wrote:As the 3rd party router becomes the querier, all 1Gbit streams of the AV encoders are congesting the link between the router and the switch.
Is this based on an effective experience or just theory? Something must go badly wrong with the IGMP snooping and the internal multicast processing on the router and the switch there. The system with the active ICMP Querier does not have to become a "core" where all multicast traffic is flowing through. Is there any L3 ICMP and multicast routing involved probably?
Regards,-Kurt
Hi Kurt,
Thank you for the quick reply.
It seems I'm not completely sure anymore on how the multicast stream flows through the network when there's not a single subcriber to the stream.
It's because of the copied text below from this forum: https://community.meraki.com/t5/Switching/Multicast-Basic-s/td-p/25706
This also means that to have a best optimized network, it is a good practice to place your querier as close to the source of your multicast traffic as possible. Since multicast traffic always flows to the querier, if the source of the traffic and the querier are at opposite ends of the network, all the multicast traffic will traverse the whole network 100% of the time, irrespective of whether receives exist.
What's your opinion on this?
Thank you.
Regards,
Kevin
Kevin,
Not sure this can be answered in a one minute reading, I'll try a very condensed reply.
In IGMPv1 and IGMPv2 snifing for GARP/GMRP this indeed an issue - this is in fact a flaw of RFC4541 which does require all Multicast traffic be sent to the IGMP Multicast router (or the IGMP Querier serving a similar purpose) - but this is sometimes conflicting with the "roaming by election" IGMP Querier. You might want to try to manipulate the IGMP Querier election by putting a lower IPv4 address onto the "fast" Netgear switch so it should be preferred over the router.
In IGMPv3 or MLD snooping for MRP/MMRP environments, this should no longer happen.
Some explanations and detailled insight on what is exactly implemented on the M4100 and even more the M4300 Series from the Netgear would be nice LaurentMa or RandyL - this should be the focus for some more white papers or a more detaille KB article.
TIA,
-Kurt
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