Martin Pro Software to iPhone App Connectivity Issue

I recently got a call from my Church asking for some help with a networking issue. Packet captures to the rescue!

Background

A Windows PC running Martin-Pro Lighting Console Software can be controlled using an iPhone/iPad app call "M-Series Remote" (aka MaxRemote). This app can remotely control various aspects of the lighting software (over the wireless network).

Problem

When connected to the same VLAN over the Ruckus AP and through a Cisco Catalyst 2960X switch, the app would *not* connect. However, going through a small Linksys WiFi router, the app connection was working just fine (see network layout below).

Fix

After running a packet capture on the PC, I noticed the Martin software was advertising a multicast stream (waiting for remote clients to connect). A quick search yielded that Cisco switches have IGMP Snooping enabled by default. Easily turned off with "no ip igmp snooping". After turning that off and restarting the lighting software, the iPhone app connected without problem!

Technical Details

It looks like the MaxRemote listens for multicast traffic (using UDP) on port 32480. The iPhone connects to the controller using the multicast stream over this same port. You can see this in the packet capture screenshot below.

10.12.14.82 = controller
10.12.14.83 = iPhone running the MaxRemote app.

• In line #151 below, the source (iPhone) is touching the multicast address (230.255.255.180) for the first time.
• The controller is responding to the iPhone in line #157 (after a successful ARP reply in line #156).
• The connection is successful in lines #173 & #179 (iPhone successfully joins the multicast group).

Multicast is much more efficient than broadcasts (especially considering the marriage of A/V and networking), so I applaud the Martin Software Engineers for forward-thinking!