wikipedia and connection-oriented and packet switching

[zillah]

http://en.wikipedia.org/wiki/Connection-oriented

An example of connection-oriented network architecture is the circuit switching network, such as was used in early telephone systems. Circuit switching networks can be used to transmit analogue or digital data. An example of the opposite would be packet switching.

,,,,,,,,,,,please pay attention to word "opposite"

In the quote above what is meant by : " opposite ." ? ,,,,was it meant to be translated as : " non connection-oriented" ? or it was meant to be translated as: "non circuit-switching " ?

Because if it is meant to be translated as : " non connection-oriented" , then I feel there is contradiction with below :

((Traditionally, three methods of switching have been important: circuit switching, packet switching , and message switching.

Packet switching itself (my concern) uses either virtual circuit approach or the datagram approach

virtual circuit approach can be divided to either permanent virtual circuit (Frame Relay )or switched virtual circuit (X.25) ,,,,both frame Relay and X.25 are connection oriented, hence it contradicts with what wikipedia syas ))

Any insight ?

Regards

[cybernetic_tiger]

Wikipedia isn't a bible and has many wierd and wonderful (completely incorrect) terms and explainations.

The term as shown on Wiki is a bit murky.

Connection-Oriented can basically be explained by the two devices needing to communicate prior to the delivery of the data from one point to another. Basically one device says to the other "get ready i'm about to start sending" and "right i've finished we can stop". This can also include the setting up of a PVC (Frame Relay) because even though no communication is required every time the device wishes to send data, the 'pipe' must be already setup to allow communication between the devices. In terms of frame relay this is done by the devices setting up one or more PVC's each with their own DLCI. TCP would also be an example of this also.

Connectionless protocols on the other hand do not require any prior session setup, no PVC and no communication is required before data can be sent. This does have its drawbacks as there is often no error recovery available with these types of connection. An example of this would be UDP/IP.

As for the switching technologies (of which there are many) there are benifits and drawbacks to each. Frame / circuit switched and now more of a legacy technology because if a PVC is mapped between two endpoints across a core network where one of the links it is mapped across drops then connectivity is lost whereas with packet switched technologies the packets can be re-routed and no reconfiguration of the path need be made.

Some examples are below :

Cell Switching:
DSL/ATM - just another way of getting into the cloud.

Packet Switching:
IPVPN - Only one pipe into the MPLS cloud is required for connectivity between all other devices within the same cloud which means there is no single point of failure.

Frame Switching:
Frame Relay where PVCs need to be configured before communication between devices can be made. If all sites have PVC's built through to the Head Office and one branch needs to connect to another this needs to be done through the head office basically creating a single point of failure. In this case a seperate PVC would be built to a DR site.

Circuit Switching:
ISDN including dialup where connections need to be built between points for communication to take place.

Hope that helps, sorry if it's a bit long winded.