I am trying to use IGMP for my NAVbus it as several systems connected to it. I am sending out a package every 1/100sec. Originally I was going to use UDP but would like to use multicast. But this network is not connected to a router to perform the IGMP tasks. since I am using a homogenous network (only ubuntu), with just a cisco 2924xlen for my switch. So this boils down to is there a way that I can use my NAVserver box as the IGMP server as well? Thanks
2 Answers
IGMP is not multicast replacement for UDP. Rather, as its name says ("Group Management Protocol"), it's the multicast control protocol, used to manage group membership for UDP (and other datagram protocols).
In order to receive multicast packets meant for a specific group (be they UDP or something else), you would first send an IGMP "join group" request. The switches along the path will note that your port wants to subscribe to that group.
(To send multicast packets, that is not required – you can just send regular UDP datagrams to the group's IP address.)
Multicast doesn't strictly require a router to work – on a small network such as yours, most of it will be handled by switches (which use IGMP to remember which switch ports have subscribed to which multicast groups).
Search your documentation for "IGMP snooping" and "IGMP querier" features.
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Just to let you know, UDP can use multicast. And IGMP uses bare IP Packets meaning, you don't need a router for it to work. Any type of network given it uses the IP Protocol should work.
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