🚀 go-pugleaf

Zellig wrote:
> 
> When working with a DatagramPacket in which layer of the OSI model am I ?
> 
> Thanks 4 your time
> Z

All of them. 

The DatagramPacket is most closely a layer 3 (Network layer) object, but
its payload contains (implicitly or explicitly) all the layers above 3. 
In addition, sending the packet requires use of layer 1 and 2.

7) Applications are sending and receiving messages to each other. 
   Otherwise, there would be no datagram packets.

6) These applications will be aware that they are communicating, so
there
   is some kind of session between the apps.

5) The payload will be using some kind of encoding (presentation)

4) There may be datagram retransmissions to overcome lost packets etc.
   This is a Transport function. Even the decision not to use sequence
   numbers and re-tx timers is a Transport layer decision.

3) The packet has IP source and destination headers (Network).

2) The packet is placed in an Ethernet, TokenRing or PPP frame when
sent.

1) The frame is sent using voltages on connector pins.


With datagram traffic, layers 4, 5, 6 are usually implicit, and it is
easier to regard everything as Application layer, since the format is
normally application specific, but the OSI model separates the functions
and specifies the layers, even if there are no bytes in the packet that
you can point at and say "that part is layer X".

Steve.