CertiGuide to Network+  9  Chapter 0100:  Network Protocols       9  III  Protocol Suite Characteristics

Routable vs. Non-routable 1 IV  IPX/SPX

This characteristic specifies whether conversations take place in a more or less structured manner. When using a connection-oriented protocol, you incur the overhead of setting up a virtual circuit (a defined communications path) between the sender and receiver, which is maintained until the sender and receiver have completed their entire conversation.

When the conversation is completed, you incur the overhead of tearing down the virtual circuit. Connection-oriented protocols provide guaranteed delivery of messages in the order in which they were sent.

Contrast this with Connectionless service, which does not require establishing a session and a virtual circuit. This can be found in the network layer or transport layer, depending on the protocol. You can think of a connectionless protocol as being akin to mailing a post card. You send it and hope that the receiver gets it. Common features of a connectionless service are:

• Packets do not need to arrive in a specific order
  
  
• Reassembly of any packet broken into fragments during transmission must be in proper order
  
  
• No time is used in creating a session
  
  
• No Acknowledgement is required.

The largest connectionless network in use today is the Internet.

Routable vs. Non-routable 1 IV  IPX/SPX