T 1.10 Failure of a wide area network

Wide Area Networks (WANs) were developed for voice and data transmissions covering long distances and can connect different LANs, but also individual computers.

In general, WANs are normally supported by telecommunication management companies, but also by private network providers. They may also belong to certain organisations and may exclusively be used by these. Therefore, the quality of the communication connections may differ.

The reasons for a failure of a WAN may be manifold. Thus, it is possible that a failure of a WAN only affects individual users, a provider, or a certain region. Often, such failures only entail brief disturbances, but there are also frequently longer failures that may result in other, dramatic problems.

The way a WAN fails plays a role if time-critical applications are operated on IT systems interconnected by means of WANs. The damage and consequential damage possibly caused by a failing WAN may be correspondingly high if no alternative options such as the connection to a redundant communication network or alternative processes for internet services are defined and/or provided.

Examples:

• A central server node of a large-scale internet provider failed. The attempt to switch to a redundant server node failed. As a result, 250,000 domains hosted with this provider were unavailable for a couple of days.
• Due to the concurrent rupture of three adjacent submarine cables in the Mediterranean Sea near Egypt, 90 percent of the internet traffic between Europe, the Middle East, and Asia was knocked out in December 2008.