oad balancing across links connecting adjacent from calls being incorrectly sent (users not entering data properly) nodes within a network. to link failures. In the most basic form the traffic is evenly balanced across all the links connecting two devices. Some systems apply a weighting 40.8.12 Call tracing factor to the links based on the link speed. The next step is to dynamically adjust the weighting factor based on the real time One of the most common problems is often referred to as call performance of the link. This ensures that a link which is performing tracing. This is rather like the PSTN namesake. If a user gets badly (perhaps due to noise on the line) is only allocated the amount connected to a faulty port on a host computer which is connected to of traffic that it can reasonably transfer. a PAD using a hunt group, it is very difficult to ascertain which is The X.25 multi-link procedures can achieve a reasonable load the offending port of the computer. This is because the logical balancing and can, depending on the implementation, provide dy- channel identifier (LCIs) change throughout the network from one namic load balancing. link to the next. Anetwork has to provide constantly updated routing The most basic requirement is that load balancing takes account tables, which display this type of information to solve this problem. of the link speed. 40.8.8 Hop counts and life times 40.8.13 Network management Hop counts and life times are used to ensure that a particular traffic Network management is one of the most important issues in net- element does not spend too much time traversing the network. The working today. A badly run network, or one which has been poorly hop count is set in a message when it enters a communications designed SO that management is difficult, can cost a company an network, to a pre-defined value. Every time the message is switched enormous amount in money and labour to maintain it. The actual (i.e. passes through a node) the hop counter is decreased. If the hop definition of net