Networks qualified network infrastructure

Computer network infrastructure should be qualified in support of validated applications. Bristol Meyer Squibb have adopted a three-level model to assist the quahfication of their computer network infrastrucmre. This approach is summarized in Table 14.3. Layer 1 comprises computers that provide shared resources such as servers, hosts, mainframes, and mini computers. Layer 2 is the network infrastrucmre (e g., hubs, routers, and switches). Layer 3 comprises the user desktop environment (i.e., workstations, personal computers, and laptops). 

The scope for quality assurance embraces all components within the Local Area Network (LAN), e.g., the bridges and routers and the interface to the public telephone and telecommunications carrier (PTT) but not beyond this. The public domain infrastructure, e.g., Internet that connects site LANS, is not within the control of the pharmaceutical organization. The PTT is entrusted to pass the signal without error to the router at the destination network interface. It is not recommended to qualify the PTT ... 

For serviceabiUty analysis, each infrastructure system will have its own unique metrics and methodologies for evaluating system performance in terms of service flow levels or qualify, fti general physical flow evaluations can be used to quantify the post-earthquake capacity of an infrastructure system. For the electric power system, for example, it is possible to determine flow at each node by solving a set of power flow equations simultaneously to find an equiUbrium state across the network (Ang et al. 1996), while hydraulic analysis can be used for flow calculations in the potable and waste water systems. The methods for each individual infrastructure system are not described here but they are based on established physical models which can be found by consulting relevant texts. 

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