The main purpose of the host to the host layer, the upper layer is shielded from the complexities of the application network transmission.
Here will be described the layer two protocol:
1 . Transmission Control Protocol ( the TCP )
2 . User Datagram Protocol ( UDP )
Transmission control protocol
transmission control protocol to obtain the information data is typically a large segment from the application, and then it is divided into several segments.
TCP data segments format
TCP header is a 20 -byte-long section, with the option can be achieved when 24 bytes.
In TCP contains the following fields of data segments:
1 . Source Port
2 . Destination port
3 . Serial Number
4 . The acknowledgment number
5 . Offset
6 . Reserved
7 . Code bit
8 . Window
9 . Efficacy and
10 . Urgent pointer
11 . Option
12 . Data
User Datagram Protocol
if the User Datagram Protocol ( UDP ) and TCP a comparison seat, UDP is basically a downsizing economy mode, sometimes referred to as thin protocol.
UDP format of the data segment
in the UDP contains the following fields of data segments:
1 . Source Port
2 . Destination port
3 . Data length
4 . CRC
5 . Data
host-to-host layer is important concepts
TCP and UDP important functions
TCP UDP
sorting disordered
reliably unreliable
connection oriented connectionless
VC low overhead
confirmation no confirmation
window to confirm the flow rate is no window or control flow