REENTERABLE MODEL OF PBB NETWORK

Abstract

For estimation of PBB network a quality of service parameters, a reenterable model has been constructed in the form of a colored Petri net. The network model consists of several components: a PBB edge switch model, a C-port and a B-port edge PBB switch; PBB backbone switch, switch and Ethernet switch ports; terminal equipment: server, workstation with measuring components; main page of the model. Models are debugged and tested in the CPN Tools modeling system. In accordance with the hierarchical principle of model construction, the reenterable PBB network model contains several levels. The top level of the model is the main page, which does not depend on the network topology and does not change when studying networks with different topologies. Network topology is a model parameter. To accurately determine the location of any message on the network, a topology descriptor (tag) is entered, containing two fields: the device address and the port number. Switching topological information descriptors in accordance with a given topology is performed using special functions. For correct switching of tags and transmission of messages in the network, availability tags of segments ports are introduced, preventing the transmission of more than one message through a port of a segment. The second level of the model is represented by the PBB edge switch model. The PBB edge switch model contains all PBB switching tables, buffers of all ports and of all switches, the number of C-ports and B-ports. Conducted computing experiments with the model. The confirmed adequacy of the constructed reenterable model in relation to the model which constructed by the principle of direct mapping. Estimations of the quality of service parameters, particularly the network response time for various network characteristics achieved using various parameters, such as the frequency of requests, the number of response frames and the running time, comparable with previous results.