Communication Abstraction

Fair-Loss Links
Properties:
Fair-loss: If a message m is sent infinitely often by process pi to process pj, and neither pi nor pj crash, then m is delivered an infinite number of times by pj .
Finite duplication: If a message m is sent a finite number of times by process pi to process pj, then m cannot be delivered an infinite number of times by pj.
No creation: If a message m is delivered by some process pj, then m was reviously sent to pj by some process pi.

Stubborn Links
Properties:
Stubborn delivery: Let pi be any process that sends a message m to a correct process pj. If pi does not crash, then pj delivers m an infinite number of times.
No creation: If a message m is delivered by some process pj, then m was previously sent to pj by some process pi.

Perfect Links
Properties:
Reliable delivery: Let pi be any process that sends a message m to a process pj. If neither pi nor pj crashes, then pj eventually delivers m.
No duplication: No message is delivered by a process more than once.
No creation: If a message m is delivered by some process pj, then m was previously sent to pj by some process pi.