Abstract
In order to achieve fault-tolerant distributed systems, checkpoint-recovery has been researched and many protocols have been designed. A global checkpoint taken by the protocols have to be consistent. In conventional network applications, a global checkpoint is consistent if there is no inconsistent message in any communication channel. However, in multimedia network applications, there are different requirements for time-constrained failure-free execution and large-size message transmissions where lost of a part of the message is acceptable by applications. This paper proposes novel criteria, consistency and duplexity for global checkpoints in multimedia network applications.