CS 551: Network Protocols

Protocol (Webster):

"an original draft or record
"a preliminary memorandum of diplomatic negotiation
"a code of diplomatic or military etiquette
"a set of conventions for formatting data in an electronic communications system"
Protocol (not Webster):

"defines the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission or receipt of a message or other event" (KurRos00)
"A design that specifies the details of how computers interact, including the format of messages they exchange and how errors are handled" (Comer99)
"An accepted or established set of procedures, rules, or formal specifications governing specific behavior or language. When applied to networks, a network protocol is a formal specification that defines the vocabulary and rules of data communication." (GalHan00)

"The OSI reference model provided a framework for talking about the overall communications process and hence was intended to facilitate the development of standards. The reference model incorporated much of the available knowledge from the research community and has served a useful role in network design for more than two decades." (L-GWid00)
"The communication between peer processes is virtual in the sense that no direct communication link exists between them"
(L-GWid00)

A five-layer protocol Application Layer Transport Layer Network Interface Link Layer Physical Layer: Bridges only use the bottom two layers; Routers or gateways use the bottom three layers
(KurRos00)

A four layer protocol: Application Layer Transport Layer Internet Layer Network Interface on top of the hardware (Physical) layer
Routers or gateways only use the bottom two layers: plus the hardware layer
(L-GWid00)

A six layer protocol: Application Layer Transport Layer (TCP/UDP) Network Layer (IP) AAL (ATM Adaptation Layer) ATM Layer ATM Physical Layer