| UDP
- User Datagram Protocol
The second protocol used at the Transport layer is UDP.
Application developers can use UDP
in place of TCP.
UDP is the scaled-down
economy model and is considered a thin protocol. Like a thin person
in a car, a thin protocol doesn't take up a lot of room - or in this case,
much bandwidth on a network.
UDP as mentioned dosen't offer all the bells
and whistles of TCP, but it does a fabulous job of transporting information
that doesn't require reliable delivery and it does so using far fewer
network resources.
Unreliable Transport
UDP is considered to be an unreliable transport
protocol. When UDP
sends segments over a network, it just sends them and forgets about them.
It doesn't follow through, check on them, or even allow for an acknowledgment
of safe arrival, in other words .... complete abandonment! This does not
mean that UDP
is ineffective, only that it doesn't handle issues of reliability.
The picture below shows us the UDP
header within a data packet. This is to show you the different fields
a UDP header
contains:
Connection-less Oriented
For those who read about TCP,
you would know it is a connection oriented protocol, but UDP
isn't. This is because UDP
doesn't create a virtual circuit (establish a connection before data transfer),
nor does it contact the destination before delivering information to it.
No 3-way handshake or anything like that here!
Since UDP assumes
that the application will use its own reliability method, it doesn't use
any, which obviously makes things transfer faster.
Less Overhead
The very low overhead, compared to TCP,
is a result of the lack of windowing or acknowledgments. This certainly
speeds things up but you get an unreliable (in comparison to
TCP) service. There really isn't much
more to write about UDP
so I'll finish here. |
