- [Instructor] A communications protocol
is a telecommunication system of rules
to allow two or more entities to transfer information.
These rules govern semantics, syntax,
and synchronization of data.
Protocols can utilize many types of software or hardware.
These communications must take place
over a common transmission system.
We generally refer to this as the network.
The framework that is most often used on a network
is the TCP/IP and OSI models.
They are both used as a roadmap for vendors
to share a common set of actions.
Modern systems use a layering technique.
Different protocols are used at various levels
to handle specific tasks.
This cooperation is often referred to as a protocol family,
or protocol suite, most notably IPX/SPX,
AppleTalk, and of course, TCP/IP.
Each layer tackles a specific problem,
then passes it onto the next,
issues like application, transport, and network.
At these varying layers,
there are a few fundamental services that need be addressed.
Data formats are crucial.
They break digital messages into bit strings
that are divided into fields
that carry relevant information.
Address formats for data exchange define the standards
by which a sending and receiving host is identified.
This could be the likes of an IP address or MAC address.
Sometimes, address mapping must be performed.
This is where one layers address scheme
is translated to another.
An example would be IP addressing to MAC addressing.
At layer three, the network layer,
routing is crucial to passing traffic
from one network to another.
If traffic cannot be transmitted reliably,
error detection can be implemented to manage the chaos.
Reception acknowledgements
can also improve transmission reliability
and are crucial to some reliable transmission types.
Another important component is how the system
should react to the loss of information.
Protocols are the basis for all network communications.