Communication Protocols for RPC

• Reliable protocols: e.g. TCP

• Unreliable datagram protocols: e.g. UDP

• Specifically designed protocols: Example

Simple Call

Client times out and retransmits request.

Three cases:
• request lost
• server still executing
• ack lost

Complicated Call

• long gaps between requests
  • acknowledge each message transmission separately
    or
  • periodically send “I-am-alive” message and use simple-call scheme.

• long messages (don’t fit into packet)
  • segment message
  • segment-relative seq #’s
  • retransmission scheme for segments

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