I think you would have to write or locate a multicast/unicast hybrid protocol. All data gets sent out multicast initially and clients can unicast request any data they were unable to receive.
Possibly you could send out 2 initial multicast streams and have intelligent clients fill in missing data from one stream with data from the other. The problem with that is that if the entire signal was blocked then you would get unicast requests from all your clients and probably DOS yourself. On Friday 11 October 2002 04:43 am, (Via wrote: > 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
