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In IEEE Std 802.1X-2010, Appendix D, Section D.8, there is the following phrase

However simple or complex, the establishment of a connectivity association for connectionless data transfer involves only a two-party interaction between the service user and the service provider (though it can result in exchanges between service providing entities in several systems) and not a three-party user-service-user interaction as is the case for connection-oriented communication.

Please help me to wrap my head around this line. What do they mean by three-party user-service-user interaction in case for connection-oriented communication in contrast to two-party interaction between the service user and the service provider?

With the continual increase in the number of ways that IEEE 802 LAN connectivity can be supported it is no longer useful to regard a LAN as definite set of physical equipment, instead the connectivity association that exists between a set of MAC Service access points defines a LAN.

Please help in understanding this with real world examples.

Full text for reference

"D.8 Connectionless connectivity and connectivity associations:

The MAC Service supported by an IEEE 802 LAN provides connectionless connectivity, i.e., communication between attached stations occurs without explicit a priori agreement between service users. The potential connectivity offered by a connectionless service composes a connectivity association that is established prior to the exchange of service primitives between service users. The way in which such a connectivity association is established depends on the particular protocols and resources that support it, and can be as simple as making a physical attachment to a wire or as complex as establishing a secure encrypted association between multiple MAC entities. However simple or complex, the establishment of a connectivity association for connectionless data transfer involves only a two-party interaction between the service user and the service provider (though it can result in exchanges between service providing entities in several systems) and not a three-party user-service-user interaction as is the case for connection-oriented communication. With the continual increase in the number of ways that IEEE 802 LAN connectivity can be supported it is no longer useful to regard a LAN as definite set of physical equipment, instead the connectivity association that exists between a set of MAC Service access points defines a LAN."

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In a connectionless communication, the only association is made between the end parties. The Internet is a good example of this. When you browse a website, you send data to the web server, and it send data back to you. No one else is involved or is even aware that you are talking to the web server.

In a connection oriented communication, there are three parties involved: you, the party you are communicating with, and the provider that sets up the communication channel. A telephone call is an example. When you call me on the telephone, you first ask the telco to set up a logical (or physical) channel between us. The telco signals to you if the communication is set up (ring tone or busy signal). Only then can we start communicating. When you are done, you "hang up", telling the telco to tear down the connection. The communication between you and the telco (and me and the telco) is the third party communication the standard is talking about.

  • Good explanation. > it is no longer useful to regard a LAN as definite set of physical equipment, instead the connectivity association that exists between a set of MAC Service access points defines a LAN. Can you explain this piece of text. Correct me if I'm wrong but in a simple LAN, there is no prior connectivity associations between any access points. – aviator Oct 23 '17 at 14:28
  • A LAN used to be defined primarily by physical equipment. If several devices were all plugged into the same switch, or tapped into the same Ethernet cable, they were on the same LAN. In modern networks, LANs can be emulated over a variety of means: VLANs and MPLS L2VPNs, for example. The devices don't need to be connected via common equipment -- they can be on opposite sides of the globe. What makes them part of the same LAN is their ability to communicate (they can address each other directly, and they all respond to broadcasts). – Ron Trunk Oct 23 '17 at 14:42
  • If you found my answer useful, please consider accepting it so it doesn't keep popping up in this list looking for an answer. – Ron Trunk Oct 23 '17 at 14:43
  • You are correct that a LAN has no prior communication associations, but what makes devices be on the same LAN is their ability to do so. – Ron Trunk Oct 23 '17 at 14:45

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