7.0 Reliability and Availability of Internet Service

For large sites (universities and corporations) that deal directly with "regional" Internet Service Providers, the Internet is highly reliable. Part of the reason for the reliability is that it is not difficult to configure alternate paths to and through the Internet "cloud". (Multiple paths through the cloud are an automatic part of the Internet operation, and reflect the fact that the Internet technology was originally designed as a "survivable" network for military use.) Alternate paths can be provided into the Internet cloud, and even (for a "small" number of sites) around the cloud (i.e. a "private" internet). These possibilities are illustrated in Figure 2.

(Click here for full size graphic)

Availability of Internet bandwidth and services are two different, and frequently confused issues. Various pieces of the Internet do get congested, however for most application the transport protocols cause this to be manifest as increasing delays for individual messages. (This is most apparent for interactive terminal sessions, where local key strokes are sent as messages across the INternet, and delay is very obvious.) People mistakenly blame un-available Web service on Internet congestion. This is almost never the case. Web client-server connect failures are usually due to limited resources available on the Web server. That is, almost all Web servers are have resource limitations that restrict the number of incoming connections, and it is this contention that causes clients to fail to be able to contact a server.

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