-
Network protocol Hierarchy :
Notes:
- Network applications
(such as
HTTP, SSH, Telnet....)
uses services provided by the
Transport Layer
software
(The most common network applications require the reliable communication provided by TCP
Other less common application uses the unreliable but speedier UDP protocol)
- Transport Layer protocol software
(TCP and
UDP)
uses services provided by the
Network Layer (IP)
software (that interconnect computers).
All computers nowadays uses the Internet Protocol (IP)
- computers using the same protocol can communicate with one another ("speak the same langauge"
- e.g., a French man and an American can't talk with one another unless one speak the language of the other)
- Network applications
(such as
HTTP, SSH, Telnet....)
uses services provided by the
Transport Layer
software
- A
network problem,
can be solved
at different protocol levels
- Effect of solving a problem at
different level:
- If a problem is
solved by
making changes in the
Application ,
then:
- the solution is
cheap and
- it can be deployed in a piece meal fashion (upgrade the application on one computer at a time)
This is the best possible scenario...
- the solution is
cheap and
- If a problem
is solved
by making changes in the
Transport Layer,
then:
-
the solution must
co-exist
with the
existing Transport Layer
(i.e., TCP and UDP) protocols.
Example: TCP Vegas must co-exist with TCP Reno
- If a problem
is sokved
by making changes in the
Network Layer,
then
- the solution must be
effective
using a
small set of routers
- Because the solution that must be deployed on all routers in the Internet , is not logistically feaible
- the solution must be
effective
using a
small set of routers
- If a problem is
solved by
making changes in the
Application ,
then: