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Communication Problems
• Flow, loss, congestion, policing
• Messages get lost due to several factors, including collisions, lack of
buffer space, lack of computing power, etc
• To allow the flow of data at a good pace, the senders of data should be
sensitive to the amount of data that is getting through (throughput of
the network). From each sender’s perspective, the maximum
bandwidth the network provides should be the upper limit on the
amount of data to be transmitted. Does this work for real-time?
• However, several senders at once may cause network congestion
• The protocol being used must provide some means of detecting lost
messages (or packets) and of correcting present and future
• Two types: hop-by-hop and end-to-end flow control and loss detection
and correction
• Trade-offs?
Flow Control
• Some methods are windows (sliding and jumping) and buckets
• Windows count the number of packets in each window and refuse any
packets that exceed the number allowed in the window
• Buckets have a (usually) constant rate of accepting packets. Any
packet in excess to that rate is not accepted (dropped)
