Furuno FELCOM 250 Service Manual

 Appendix 4. Abbreviations
AP4-9
Protocol
8 bit; it represents the type of the upper layer protocol where the host IP software
would refer to this protocol number field to identify to which upper layer protocol it
is required to deliver the IP packet data part it had received.
Header Check-Sum
16 bit; the header only is checked by CRC.
Source address
32 bit; it represents the sender's address.
Destination address
32 bit; it represents the recipient address.
Option
The field which gives the instruction for special processes when such processes are
required for delivering the IP packets.
Padding
When option is used, there are some cases where the length of the header would not
be the integral multiplication of 32 bit; this filed is used for adjusting such status to
make the resulting value an integral multiplication of 32 bit.
UDP (User Datagram Protocol)
A standard protocol used in the Internet, and it is equivalent to the transport layer for
the OSI reference model. It works as a bridge between the IP for the network layer
and the protocol in the session layer and above. TCP is used as the protocol for the
transport layer in the Internet; the forwarding speed for UDP is faster but its
reliability is low whereas the forwarding speed for TCP is slower but its reliability is
high.
The UDP Header Format is as described below;
0 4 10 16 31
Source Port Destination Port
Length Checksum
Data
Source Port
16 bit; the sender's port number
Destination Port
16 bit; the recipient port number
Length
16 bit; it specifies the overall length of the packet including the header part and the
data part.
Checksum
16 bit; TCP calculates the data sum in order to guarantee the data reliability.

Furuno FELCOM 250 Specifications

General

Brand	Furuno
Model	FELCOM 250
Category	Marine GPS System
Language	English