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Protocol (network): a communication standard for network/host devices that facilitates messaging between entities.

Complete Definition:

It is difficult to generalize about protocols because they vary so greatly in purpose and sophistication. Most protocols specify one or more of the following properties:

  • Detection of the underlying physical connection (wired or wireless), or the existence of the other endpoint or node
  • Handshaking
  • Negotiation of various connection characteristics
  • How to start and end a message
  • How to format a message
  • What to do with corrupted or improperly formatted messages (error correction)
  • How to detect unexpected loss of the connection, and what to do next
  • Termination of the session or connection.

Wikipedia Definition of Network Protocol

Some Common Protocols examples (***Not an exhaustive list):

Network Layer 3 Protocols:

  • IP (Internet Protocol)
  • UDP (User Datagram Protocol)
  • TCP (Transmission Control Protocol)
  • ICMP
  • IPX

  • Appletalk



Layer 2 LAN Protocols:

Layer 2 protocols are responsible for converting data packets passed to it by the Network/Internet Layer (above) into binary data in frames. This data is passed to the Physical Layer.

  • STP (Spanning Tree Protocol)

Routing Protocols:

A routing protocol is a set of rules or standard that determines how routers on a network communicate and exchange information with each other, enabling them to select best routes to a remote network.

WAN protocols:

  • Frame relay
  • HDLC
  • ATM
  • DSL
  • X.25
  • ISDN
  • LAPB
  • SDLC
  • PPP

Application protocols:

  • DHCP (Dynamic Host Configuration Protocol)
  • HTTP (Hypertext Transfer Protocol)
  • FTP (File Transfer Protocol)
  • Telnet (Telnet Remote Protocol)
  • SSH (Secure Shell Remote Protocol)
  • POP3 (Post Office Protocol 3)
  • SMTP (Simple Mail Transfer Protocol)
  • IMAP (Internet Message Access Protocol)

And MANY MANY more not listed.