Connections

A connection is an instance of communication link between two processes. Each connection is specified by a unique 5-tuple, called a association��:

1. �Protocol (e.g., tcp, udp)
2. �Local Address (Net ID + Host ID)
3. �Local Process (Port Number)
4. �Foreign Address (Net ID + Host ID)
5. �Foreign Process (Port Number)

For instance,

� { tcp, 128.10.9.3, 1500, 128.10.0.7, 21 }

One half of an association is called a socket��. An association is thus a 3-tuple (the protocol is duplicated in a socket pair).