This document discusses different modes of communication in distributed systems including unicast, anycast, multicast, and broadcast. It then covers topics related to implementing group communication such as hardware vs software approaches, reliability, ordering of messages, and protocols like IP multicast and IGMP.

1. Introduction Paul Krzyzanowski [email_address] [email_address] Distributed Systems Except as otherwise noted, the content of this presentation is licensed under the Creative Commons Attribution 2.5 License.

5. Implementing Group Communication Mechanisms

10. Reliability of multicasts

16. Message ordering

17. Good Ordering Process 0 order received a , b a , b message a a message b b

18. Bad Ordering Process 0 order received a , b b , a message a a message b b

19. Good Ordering Process 0 Process 1 message a a message b b order received a , b a , b

20. Bad Ordering Process 0 Process 1 message a a message b b order received a , b b , a

22. Sending, delivering, holding back sender receiver Multicast sending algorithm Multicast receiving algorithm hold-back queue delivery queue discard ? sending delivering

29. Multicasting considerations atomic reliable unreliable unordered sync causal total global unordered FIFO Message Ordering Reliability

30. IP Multicasting

44. The end.