The present invention pertains to packet data traffic through a network and more particularly to cumulative delays in node to node transfer of packet data through an internet protocol network.
Modern high speed communication networks send information, which may be data or voice information, from one network to another or from one node in a network to another node in a network. The packet data is routed or sent from node to node through a network moving towards its final destination. Network nodes are switch points which may direct the data packet to various other nodes within the network or to other networks. These network nodes temporarily stop and hold or queue data packets before forwarding them on to another selected node. The flow is similar to that of an automobile moving down a street with other traffic being periodically stopped by traffic lights.
Each node to node transfer is termed a hop. Typically transferring from node to node through an internet protocol network requires a multi-hop path. This means that several nodes will receive, temporarily store or queue and then forward the data packet to another node.
Each data packet includes a header which is a specified number of data bits which indicate the destination and a type of service field that is used to allow routers and servers, which are network nodes, to distinguish the priority of each data packet. At each network node the data packets are queued for transmission. Since transmission lines which link the network nodes have fixed bandwidth or capacity, the transmission of each data packet must be scheduled in sequence. Hence, while one data packet is being transmitted many other data packets will have to wait or be queued. Some network nodes may substantially delay the data packets"" transmission through the network while others may provide only minimal or marginal delay. The delay depends upon the position within each network node""s queue in which the data packet resides. A number of prioritized queues may exist at each network node based upon the priority markings contained in the header.
Traffic such as voice over IP, streaming traffic, and TCP traffic is sensitive to delay variation within a network. Delay variation contributes a reduction in the quality of the service perceived by the end user or application.
Accordingly, it would be highly desirable to have an internet protocol network which minimizes the overall delay associated with transmitting a data packet through this network.