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[[transmission]]. Rather, each [[router]] calculates the best [[routing]] for a [[packet]] at a particular moment in time, given current [[traffic]] patterns, and sends the [[packet]] to the next [[router]]. Thus, even two [[packet]]s from the same [[message]] may not travel the same physical path through the [[network]]. This mechanism is referred to as "[[dynamic routing]]."
 
[[transmission]]. Rather, each [[router]] calculates the best [[routing]] for a [[packet]] at a particular moment in time, given current [[traffic]] patterns, and sends the [[packet]] to the next [[router]]. Thus, even two [[packet]]s from the same [[message]] may not travel the same physical path through the [[network]]. This mechanism is referred to as "[[dynamic routing]]."
   
When [[packet]]s arrive at the destination point, they must be reassembled, and [[packet]]s that do not arrive for whatever reason must generally be re-sent. This system allows [[network]] resources to be used more efficiently, as many different communications can be [[routed]] simultaneously over the same [[transmission]] facilities. On the other hand, the inability of the sending [[computer]] under such a "[[best effort]]" [[routing system]] to ensure that sufficient [[bandwidth]] will be available between the two points creates difficulties for services that require constant [[transmission rate]]s, such as [[streaming video]]
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When [[packet]]s arrive at the destination point, they must be reassembled, and [[packet]]s that do not arrive for whatever reason must generally be re-sent. This system allows [[network]] resources to be used more efficiently, as many different communications can be [[routed]] simultaneously over the same [[transmission]] facilities. On the other hand, the inability of the sending [[computer]] under such a "best effort"<ref>In a ''best effort'' delivery system, [[router]]s are designed to "drop" [[packet]]s when [[traffic]] reaches a certain level. These dropped [[packet]]s must be resent, which to the [[end user]] is manifested in the form of delay in receiving the [[transmission]].</ref> [[routing system]] to ensure that sufficient [[bandwidth]] will be available between the two points creates difficulties for services that require constant [[transmission rate]]s, such as [[streaming video]] and voice applications.
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and voice applications.
 
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== References ==
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<references />
   
 
[[Category:Technology]]
 
[[Category:Technology]]

Revision as of 04:30, 4 January 2008


A packet-switched network means that data transmitted over the network is split up into small chunks, or "packets." The Internet is a packet-switched network.

Unlike "circuit-switched" networks such as the public switched telephone network (PSTN), a packet-switched network is "connectionless." In other words, a dedicated end-to-end transmission path (or circuit) does not need to be opened for each transmission. Rather, each router calculates the best routing for a packet at a particular moment in time, given current traffic patterns, and sends the packet to the next router. Thus, even two packets from the same message may not travel the same physical path through the network. This mechanism is referred to as "dynamic routing."

When packets arrive at the destination point, they must be reassembled, and packets that do not arrive for whatever reason must generally be re-sent. This system allows network resources to be used more efficiently, as many different communications can be routed simultaneously over the same transmission facilities. On the other hand, the inability of the sending computer under such a "best effort"[1] routing system to ensure that sufficient bandwidth will be available between the two points creates difficulties for services that require constant transmission rates, such as streaming video and voice applications.

References

  1. In a best effort delivery system, routers are designed to "drop" packets when traffic reaches a certain level. These dropped packets must be resent, which to the end user is manifested in the form of delay in receiving the transmission.
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