Protocols
Protocols are software and must be installed on network components
that need them. Computers can communicate with each other only if
they use the same protocol. If the protocol used by a computer in a
network is not compatible with the protocol used by another
computer, the two computers cannot exchange information. A variety
of protocols are available for use in specific network environments.
Although each protocol facilitates basic network communication, each
has a different function and accomplishes different tasks. You can
understand the function of different protocols by examining the
standard model for networks—the Open Systems Interconnection (OSI)
reference model. This model is built around a set of seven protocol
layers, and each layer is responsible for some function that assists
in the transmission of data over the network.
According to the OSI conceptual model, several protocols must work
together to ensure the proper transmission of data. In reality, this
is achieved with the help of a
protocol stack.
A protocol stack is a collection of protocols that function together
to transmit data across a network of computers.
Types
of Protocols
Two
types of protocols are available today: open and vendor-specific.
Open
Protocols
Open
protocols are protocols that are written to publicly known industry
standards. A protocol that adheres to these industry standards is
compatible with other protocols written to the same standards. Open
protocols are
nonproprietary (not privately owned). A common example of an open
protocol is Transmission Control Protocol/Internet Protocol
(TCP/IP), which is used as the standard for communication over the
Internet.
Vendor-Specific Protocols
Vendor-specific protocols are proprietary and have been developed by
different vendors for use in specific environments. For example,
Novell provides a set of protocols, such as Internetwork Packet
Exchange/Sequenced Packet Exchange (IPX/SPX), developed
specifically for its NetWare architecture.
