Protocols define rules for communication between network devices to ensure successful transmission of messages. They specify how to initiate and terminate connections, message formats, and how devices share path information. Related protocols are grouped into protocol suites, like TCP/IP. Networking professionals use protocol models that describe specific suites and reference models that provide a common framework, like the OSI model, to understand network communication processes.

2.  Protocols are rules used by anyone who communicates
with another.
 Protocols make communication successful.
 The need for protocols also applies to network devices.
 Rules for communication that must be strictly followed
for successful host-to-host communication.

3.  Protocols define / provide:
◦ The process to initiate and terminate
communications between hosts.
◦ Message format.
◦ The way of intermediary devices share the information
about the path to the destination.
◦ The method to handle update messages between
intermediary devices.
◦ Technology Independence
◦ Standardization

4.  Rules or protocols that work together to ensure
successful communication are grouped into what is
known as a protocol suite.
 Example: TCP / IP

5.  Networking professionals use two networking models to
communicate within the industry:
1. Protocol Models:
◦ A model that that closely matches the structure of a
particular protocol suite. Example: TCP/IP Model
2. Reference Model:
◦ A model that provides a common reference for
maintaining consistency within all types of network
protocols and services.

6.  Reference Models:
◦ Not intended to be implementation specification
◦ Aims to provide clearer understanding of the
processes and function involved in communication.
 Example: OSI Model / Internetwork Reference Model
 OSI vs TCP /IP Model
 OSI model, provides an abstract description of the
network communication process.
 Important to know to understand the entire network
communication process.

7.  TCP / IP describes the functionality of the protocols that make up
the TCP/IP protocol suite.
 Important to understand how the process is implemented in current
networks.