A communication channel can be described in terms of four attributes:

• Performance – dictated by the network latency and bandwidth

• Reliability
  • Validity - a message put in the outgoing buffer is eventually delivered to the incoming message buffer
  • Integrity – the message received is identical to the one sent, and no messages are delivered twice
    
    
• Ordering
  • A channel is ordered if messages are delivered in the order in which they were sent 
    
    
• Synchronicity
  • Synchronous – each message transmitted over a channel is received within a known bounded time
  • Asynchronous – message transmission time is unbounded