Path: utzoo!attcan!uunet!ogicse!ucsd!ucbvax!HPSDEL.SDE.HP.COM!wunder From: wunder@HPSDEL.SDE.HP.COM (Walter Underwood) Newsgroups: comp.protocols.tcp-ip Subject: Re: Reliable Broadcasts? (was Re: Reliable Datagram ??? Protocols) Message-ID: <9010251640.AA01218@hpsdel.sde.hp.com> Date: 25 Oct 90 16:40:13 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 18 I'm surprised that no one has mentioned Cornell's ISIS system. ISIS is a reliable multicast system with ordering guarantees. The hard part about multicast designs is not the protocol, but proving that the resulting system behaves correctly. ISIS provides a choice of orderings; two of the choices are causal ordering within the process group and causal ordering across all groups. This ordering makes designs much, much simpler. If you are already guaranteed that processes will see the same messages in the same order, then any deterministic calulations will get the same result. Notification of failures in the process group (or processes joining or leaving) are ordered like other messages. For more info, see the newsgroup comp.sys.isis, or send mail to Ken Birman (ken@cs.cornell.edu). The ISIS code is available, and runs on LOTS of systems. wunder