Different “classes” of service are required to cover different data flow needs
Circuit connect (like the telephone system)
Exclusive connection Full bandwidth reserved
Packetized (“frame by frame” routing)
Connectionless
May take a variable path Efficient and flexible use of available resources
Guaranteed bandwidth for “Quality of Service”
Reserved connection Shares available bandwidth Typically required for multimedia applications Unidirectional Virtual Circuit established
There are three basic concepts associated with data connections:
o Circuit Connect: This is most easily described as a telephone connection. Two Fibre Channel devices want to make a connection so that they can communicate with each other – without any other device being able to communicate with them. The two devices first make a connection, then data is exchanged and then the connection is broken. Using the telephone analogy step one - ‘dialling a number’ step two = ‘holding a conversation’ step 3 - ‘hanging up the phone’
o Packetized: This is the way in which LANs typically work. A ‘frame’ or
‘packet’ of data is routed to a destination based on the address in the frame/packet header.