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Network Domain

The Network Domain maintains standards and policies that enable a common, uniform network infrastructure that provides transparent, reliable and ubiquitous communications for DHS's distributed information processing environment. This domain contains standards regarding every aspect of networking within DHS, Business Partner and interagency computer connections to DHS, and the use of wireless and video conferencing technologies throughout DHS.

The infrastructure of most large-scale business operations at DHS consists of a series of Local Area Networks (LAN) connected together on a Wide Area Network (WAN). This topology allows for the seamless integration between, and centralized administration of, all of the devices within the DHS. The principles that govern good network design include the ability to provide a wide range of applications and resources, affordability to the organization, high reliability, scalability, and support of new technologies.

This section consists of the following areas:


    • Landlines — Modern telephone communication systems are generally classified by the number of telephones and telephone lines they support. The classification is either "Small" or "Large", depending on the number of stations (telephones) served by the system. Generally, a Small system is one which has 60, or less, stations. A Large System has over 60 stations. This is a general rule, because some Small systems may be capable of being expanded, while others may have a smaller station capacity. These systems are further classified according to their internal architecture (construction) and as to whether the central controlling mechanism for the system is placed on the customer's premises or elsewhere, such as in a telephone company's central office. There are numerous advantages and disadvantages to each type of telephone system. Generally speaking, the cost per station and the functionality of the telephone system improves with the size of the system. DHS primarily uses either Centrex or PBX/Small Key configurations according to site location and requirements.
    • CENTREX — A private telephone communication system provided on a lease basis by the telephone company (Currently, almost all leases are with Level 3). This service includes various features provided by equipment located on facilities operated and maintained by the telephone company. This facility is referred to as the "Central Office". The Central Office or "CO" is usually located in or near the community in which DHS and/or other agencies of the Commonwealth have offices. Features are extended to the DHS' premises by local telephone wires or fiber.
    • PBX/Small Key — A PBX (Private Branch Exchange) or Small Key System is a series of telephone equipment and features provided by small computer-based equipment, commonly referred to as a "SWITCH". The Switch controls a given number of on-premise telephones and related equipment. In addition, it interconnects telephone calls off-premise, usually via telephone lines to the public telephone network. A PBX usually, but not always, requires an attendant, who intercepts incoming calls and distributes the call to the caller's desired destination. Since a PBX concentrates a relatively large number of on-premise telephone lines to a small number of outside public telephone lines, and because it potentially provides tighter controls and accountability for telephone utilization, it may be the most cost-beneficial system when the number of telephones supported by the PBX exceeds 60. Small Key Systems are utilized to handle 80 lines or less. Environmental matters of air conditioning and heating must be considered when deploying a PBX or Small Key Systems.
    • Wireless — A Wireless Communications Device transmits and receives data, text, and/or voice without being physically connected to a network. This definition includes but is not limited to such devices as cellular telephones and wireless data devices (e.g., Blackberry Devices). The portability, small size, coverage area and capabilities of these devices make them an attractive option for a variety of data communication needs. However, the documents below are meant to address issues related to the use of such devices as a telephone

(This subsection contains standards and policies regarding WAN, MAN, and LAN network connections at various DHS office locations)

In addition, generic WAN, MAN, and LAN standards and policies, which pertain to the three subsections above, are listed below:

Network Connectivity

    • Wireless Lan Technology (Information Technology Bulletin ITB-NET001) - Detailed overview of Commonwealth LAN Technologies
    • DHS Wireless Connectivity

    • Video Conferencing - allows people to conduct a conference between two or more participants at different sites by using computer networks to transmit audio and video data. Multipoint video conferencing allows three or more participants to sit in a virtual conference room and interact as if sitting right next to one another.
  • Physical Media and Mechanisms - the physical hardware and wiring that enable networks to function. The more popular cabling, or media, used in land-based networks include shielded and unshielded twisted pair, coaxial, and fiber-optic. Other types of physical mechanisms include switches, routers, hubs, and concentrators. Without such physical means, networks would merely be conceptual ideas. This section consists of the following areas: