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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:

Telephones

    • 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.

    • Skype for Business — Allows you add up to 250 people to online meetings, provides enterprise-grade security, allows you to manage employee accounts, and is integrated into your Microsoft Office apps.

Policy
    • 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., iPhones and Air Cards). 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
Policy
Procedure
    • Wide, Metropolitan, and Local Area Networks — Network administrators often classify networks according to geographical size. The smallest kind, Local Area Network (LAN), is a group of computers and other devices within a geographically limited area, such as a building or campus. Wide Area Networks (WAN) and Metropolitan Area Networks (MAN) interconnect several LANs. In addition, a WAN can connect several MANs. Computers withing a WAN exist within an unlimited geographical area. WANs can utlilize telephone lines or radio waves and typically transfer data at lower speeds than LANs. A MAN is more geographically confined than a WAN. MANs are usually high-speed connections using fiber-optic cable or other digital media. 

        • DHS — This subsection contains standards and policies regarding WAN, MAN, and LAN network connections at various DHS office locations
Standards
Templates and Forms
In addition, generic WAN, MAN, and LAN standards and policies, which pertain to the three subsections above, are listed below:


Policy

Standards

Guidelines

Standards

  • 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.

Policy

  • Cabling — Physical network cabling, or bounded media, enables the transmission of electronic signals from one network device to another. Such network transmission media include coaxial, shielded and unshielded twisted-pair, and fiber-optic. Each has specialized characteristics applicable to different network types. The following chart shows the similarities and differences in the cabling types listed above.

Cable Type

Cost

Capacity

Range

Coaxial Thin net

Less than Shielded Twisted-Pair

10 Mbps

185 m

Coaxial Thick net

Greater than Shielded Twisted-Pair, Less than Fiber

10 Mbps

500 m

Shielded Twisted-Pair (STP)

Greater than Unshielded Twisted-Pair, less than Thick net

16 - 500 Mbps

100 m

Unshielded Twisted-Pair (UTP)

Lowest

100 Mbps

100 m

Fiber-optic

Highest

100 Mbps

10s of Km


Generic cabling standards and policies, which pertain to these two subsections, follow:

    • Fiber Optics — This section contains all formal DHS standards and policies regarding fiber-optic network cabling used at DHS locations.

    In addition, generic cabling standards and policies, which pertain to these subsections, follow:

    Layer

    Name

    Function

    7

    Application Layer

    Program-to-program communication.

    6

    Presentation Layer

    Manages data representation conversions. For example, the Presentation Layer would be responsible for converting from EBCDIC to ASCII.

    5

    Session Layer

    Responsible for establishing and maintaining communications channels. In practice, this layer is often combined with the Transport Layer.

    4

    Transport Layer

    Responsible for end-to-end integrity of data transmission.

    3

    Network Layer

    Routes data from one node to another.

    2

    Data Link Layer

    Responsible for physical passing data from one node to another.

    1

    Physical Layer

    Manages putting data onto the network media and taking the data off.

    This section consists of the following areas: