First of all, I know nothing about IP Multicast. (But I am reading Stevens...)
I have a system with several hundred machines on it and I need to keep each system updated with various pieces of information including various heartbeats, pieces of state information. The machines are all behind our firewall, but there are so many they do live on different segments of our net (i.e. there are many routers.) I believe there are too many systems to use typical tcp/ip unicast connections, and it strikes me that this may be a good use if broadcast or ip multicast. My understanding so far of multicast is that it's not a protocol in and of itself, it's a technique that we can layer a protocol on top of. So using my favorite Swiss Army knife, I am thinking of creating an AOLserver module that can perform http gets or posts using either a broadcast or ip multicast, and making changes to nssock (or creating a new module) that enables AOLserver to listen for http requests over broadcast or ip multicast. Am I just an ignorant ass or would this be interesting, useful, and implementable? (or all of the above?) Before going to AOLserver, are there any tools already out there that can be used to make for an efficient information bus using broadcast or ip multicast? If I do choose to build such a module and create some form of bus on top of it, what are the pitfalls I should be aware of? And since I believe that broadcast and ip multicast are UDP and inherently unreliable, what are the common techniques used to make for a reliable multicast? In fact, googling on reliable multicast leads me to a few commercial products and a CISCO specification of PGM, pragmatic multicast. Is there a standard reliable multicast protocol that I should look to? Thanks! Jerry
