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 layer]]s, 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]]