View source for Data packet

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A data packet is a formatted block of data sent across a [[computer network]].

==Packet header==
Each individual data packet includes a packet header, containing information on the packet's destination. The header informs the [[nodes]] where to send the data packet. The header includes the following information about the packet's destination:
*The [[IP address]] number, which identifies the [[computer]] the data is to be sent to
*The [[port]] number, which identifies a particular [[process]] running on the destination Computer

The computer's [[IP address]] is like the street address of an apartment building, while the [[port]] number is like the number of a particular apartment within the building.

The [[IP address]] and the [[port]] number together make up an [[internet socket]], which is one of the end-points of a two-way communication flow between specific application processes running on two different devices connected to the Internet. 

==Packet forwarding and packet routing==
Data packets are [[Packet forwarding|forwarded]] from one [[network segment]] to another by [[nodes]], and [[Packet routing|routed]] to their final destinations.

[[Packet forwarding]] takes place just from one [[node]] to the next, while [[packet routing]] selects the path of links over which to send the packet towards its final destination.

Packet forwarding is handled at lower network layers, while packet routing involves higher network layers. Forwarding and routing are generally described in terms of one or the other of the two standard [[network protocol]]s: the [[Internet Protocol]] or the older [[OSI protocols]].

==See Also==
*[[IP address]]
*[[Port]]
*[[Internet socket]]
*[[Packet forwarding]]
*[[Network protocol]]

==External Links==
*Wikipedia article about data packets: http://en.wikipedia.org/wiki/Packet_%28information_technology%29
*Wikipedia article about IP addresses: http://en.wikipedia.org/wiki/IP_address
*Wikipedia article about ports: http://en.wikipedia.org/wiki/TCP_and_UDP_port
*Wikipedia article about internet sockets: http://en.wikipedia.org/wiki/Internet_socket

[[Category:Network protocols]]