We refer to the set of processors within a broadcast domain that can communicate with each other as a ring or the membership of a ring, and use the term configuration to define a particular membership view provided to the application.
A Configuration Change message, delivered by the single-ring protocol, signals a membership change within a broadcast domain. A Topology Change message, delivered by the multiple-ring protocol, signals a topology change within the larger network.
1995], except that they define topologies system-wide rather than configurations for a local broadcast domain. The multiple-ring protocol provides the following services:
Switches can use Layer 4 information to differentiate quality of service (QoS) for security purposes, or to create broadcast domains. All of these are good and useful things.
Layer 4 addresses also can be used to build broadcast domains or virtual LANs.