Abstract:
In the paper, an abstract model of a distributed network containing only hosts and switches is developed; this model allows us to estimate some problems that need to be solved in such a network, taking into account, among other things, non-functional parameters. It is assumed that hosts offer packages of certain services, and messages (requests) between hosts are forwarded via intermediate nodes according to switching rules. A rule determines which neighboring nodes a message received by a node is forwarded to, depending on where the message came from and the parameter vector in its header. Accordingly, the configuration of nodes determines the set of paths from host to host along which packets will be forwarded. The situation is modeled using a graph of physical connections, the vertices of which are hosts and switches, and the edges correspond to the physical connections between them. It is usually assumed that only hosts in such a network receive, process, and send information to other hosts, but do not switch messages. This function is assigned to other nodes, switches. However, we assume that with modern technologies, in some cases a host can perform the switching functions, i.e. such a host (like a switch) contains a system of switching rules that specify where the received message is sent if for some reason the host cannot process the obtained request/message. A network model is proposed in which the message switching function is performed not only by each switch, but also by each host. The paper discusses the problems associated with non-functional parameters of a distributed network, namely, reachability/unreachability of hosts, message looping, network overload with messages, and non-scalability. Optimization issues of the network parameters are discussed based on the set of services provided by each host. In addition, we discuss self-tuning algorithms for a distributed network that optimize network parameters, message transmission over the configured network and incremental (repeated partial) self-tuning algorithms when changing network parameters, in particular, its topology that does not disrupt network operation.
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