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T1s can be used for server connections. Using a T1, servers can connect to each other. A T1 used for connections to a server is known as a data T1 when it carries only digital data. Since a data T1 carries only data services, it will typically be terminated by a Mux (or directly into a router, which is sometimes erroneously referred to as a T1 server). From the router, a direct Ethernet connection will typically be made at 100Mb or 1Gb to a server, workstations, or a combination of both. The router acts in a "traffic management" role, and also provides critical firewall and security services to protect the server. Servers act in a number of capacities for today's enterprise network. From the simple file server setup with FTP access from outside a firewall, to web servers, application servers, development servers, and more, today's enterprise network environment is all about servers with ample amounts of bandwidth available. T1s used for server communication are generally carrying either IP-based services, or Frame Relay services. Either way, the T1 may be designated as a server's T1 since it only carries data for the Local Area Network to use. In a converged network, voice may be combined, but to the network, it represents only another class of data packet. Server Varieties. Servers today are configured in a variety of ways, from the simple to the Raid-Array, multiple processors, and redundant-power supply workhorses of today's demanding enterprise network environment. Actually, any common computer with sufficient hard drive space, RAM, and processor speed could function as a server, provided the operating system is changed to one of the Windows Server OS varieties (2000, 2003, and Longhorn coming soon) or one of the Unix / Linux varieties. Even a Pentium III PC, 256kb of Ram and a 20Gb hard drive can run Windows 2000 server. As server reliability, speed, and storage requirements increase, the price tag goes up. Add additional RAM for a few hundred dollars, add a second, third, forth, or more hard drive for either additional storage space, or (configured with a RAID controller) redundant data replication that can be hot-swapped in case of a single drive failure. Dual power supplies are a must in a high-availability environment, and be sure to specify adequate UPS protection for low/no voltage conditions as well as spike protection during thunderstorms. All of these improvements can push the cost of a server from under $1000 to several thousand, depending upon all the options needed. Bandwidth Considerations. A single T1 used for server |
T1 Server
communications may be adequate under normal operating conditions. If applications or data resident upon a server in a multi-location environment are considered "mission-critical", some Business Continuity Planning efforts must go into the overall design to ensure availability in case of hardware, T1 link, or site failures. If a mesh T1 network (see right) is adequate for normal conditions, but there are critical functions at two of the sites, multiple T1 links may be required for automated fail-over protection. If absolute real-time restoral capability is a requirement, designers will effectively double the bandwidth on the network to allow for real-time data replication between sites. If all of this is above your level of understanding, consider the services of an experienced Network Design Consultant with significant BCP and Disaster Recovery Planning experience. 
