Packets
A data packet is also known as a datagram, frame or a cell. Data on the network and on internet is transmitted in the small chunks known as packets. A packet is a basic unit of communication over the digital network. The structure of the packet depends on the type of it and the type of the protocol. When a client computer transmits the data over the network, it uses the client network software to enclose the data in the packet that also contains the header and footer. Different data types use different protocols.
Every packet is composed of the header and the trailer and they contain the information to the destination computer. The header portion of the packet also contains the overhead information and the transmission related things. The rate at which data packets are transmitted is known as bandwidth. Bandwidth is also known as the capacity of the channel. The IP packet includes the following.
- Source IP Address
- Destination IP Address
- Sequence number of the packets
- Flags
- Overhead information
- Protocols
- Header Checksum
- Fragmentation offset
- Data (bits)
- Total Length
- Time to live
When data is transmitted over the network, it is broken down into the smaller pieces, which are then reassembles at the destination. Packets are transmitted as a electrical signals in the electrical wires, the light signals in the fiber optic cables and they are transmitted as the electromagnetic waves when they are transmitted through the space. Most of the packets are consist of the following three parts.
The header includes the length of the packet, synchronization, packet number, source IP address, destination IP address and the type of the protocol that is being used to carry the information such as email, web page, streaming video and audio.
Payload also known as the body of the packet and it contains the actual data.
Trailer is also known as the footer. Trailer contains some bits that are used for the error checking. The most common error checking is known as Cyclic Redundancy Check (CRC).
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