Hi all
I'm having a network with allot of coustomers connecting in with L2TP. We are now adding multicast to this network but after 33 interfaces are going online I'm getting the error "PIM interfce limit reached". Any one having a nice workaround for this?

This is a Linux kernel limitation, you can have maximum of 31 multicast interfaces. (Well, 32 in fact, but one index is always used for the automatically create "register" multicast tunnel interface).
There are no real workarounds, except bridging the interfaces together, so that from routing protocol point of view they will look like one interface.

Hi Atis,

You helped us with the information that there was a PIM Interface limit, which was fixed by Mikrotik from RouterOS 4.6. I have posted a new thread with another PIM issue we are trying to understand and wonder if you can assist

http://forum.mikrotik.com/viewtopic.php?f=2&t=43017

We are using Multicast extensively with Mikrotik and have a big issue with multicast traffic.

Have a problem with high concurrency multicast streaming, but don’t have a specific number of clients that starts to impact quality – or it's a problem with the volume of packets via each igmp group. For example if 70 people watch a football game (1.5mb stream rate) the quality is very poor during the “fast” action time, but quality improves when things are moving slowly, for example when interviewing people, even though the same number of viewers are watching the same stream? We want 100's of clients to want each channel. We now believe this issue looks more and more as though it's related to a 32 user PIM limit, at which point streaming IPTV quality starts to drop (using V4.10).

Viewing multicast traffic (via mangle) we often have Rate > 100mbps & Packet Rate > 15,000p/s – is there any limits applicable to individual IP igmp streams – does Mikrotik have any “internal” settings, such as the PIM Interface limit of 32 that was set before RouterOS 4.6?

by the way:

What's new in 4.6:

*) remove limit on number of multicast enabled interfaces, maximum was 32;

We have been using 4.6 (now using 4.10) with unlimited PIM Interface and it works great, with no noticeable load on our RB1000 (we have nearly 1,000 concurrent users, each with a PIM interface PPPOE via L2TP) with CPU 40%-50%, Memory 75mb and very stable.

The problem we have is when more than 32 concurrent users view an igmp group (a TV channel) the quality starts to degrade a lot (less than 32 concurrent per igmp group and the quality is excellent). This number seems "coincidental" reference the 32 limit – this is the problem we have.

Please could anyone offer an update reference this issue, as a limit of +/- 32 concurrent PIM Interfaces on 1 igmp group restricts RouterOS massively and I'm sure multicast is becoming more relevant all the time?

The original 32 PIM Interface limit (fixed with RouterOS 4.6) was resolved quickly and this is as important an issue, even though not identified at the time of 4.6 release.

I sent a ticket to support [Ticket#2010070466000061] 3 weeks ago without any reply and would love an update - it’s a big problem for our business.

Kind regards,