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Tele Medical Health Hipaa Dicom HL7 Pacs.Com, Inc. Information Technology Documentation

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Appendix A

APPENDIX

Categories of Wire

There are several categories of wire recognized in the EIA/TIA standards. Category 5 wire - four-pair, unshielded twisted pair (UTP) - is the cable of choice because of its 100 Mbps capability. The network software and hardware other than the cables will determine the actual network speed.

You will encounter the terms plenum or nonplenum. Plenum or nonplenum wire refers to the outside insulation used on the wire. Nonplenum wire uses a standard PVC plastic for the insulation; plenum wire has special plastic insulation around it which, in case of a fire, has special non-toxic fume characteristics. Plenum wire typically is double the cost of nonplenum wire. Safety considerations, as well as building and fire codes, will determine the use of plenum or nonplenum wire.

Existing installations already might have other types of cables such as thin or thick ethernet, arcnet or shielded twisted pair. These can be continued to be used. There are media changing devices available to join many different network cable systems.

Connectors

All wire cable connectors (jacks and plugs) in an installation should be RJ-45 Category 5 connectors. RJ-45 connectors are similar in appearance to standard RJ-11 telephone connectors, which usually have 4 pins, but RJ-45 connectors are wider and have eight pins.

When Category 5 cable is terminated to a connector (jack or plug), there are eight color-coded wires (four twisted pairs). The standards define two different pin/pair assignment combinations. They are T568A and T568B. The main difference between the two standards is the juxtaposition of the orange and green pairs. A cable that is wired T568A at one end and T568B at the other end will not work. Most commercial and school installations are going with the pin/pair assignment designated T568B.

Standard EIA/TIA T568B (also called the AT&T specification, previously called 258A):

Wiring installers memorize this configuration and then wire a building without seeing all the other parts of the network. Installers assume that the other cables and devices are wired to the same standard. An installer can arrive months later and successfully add or change cables without seeing any cable but the one being configured.

Structured cabling: cat 6

cat 6 - Category - 6, (ANSI/TIA/EIA-568-B.2-1) A cable standard for Gigabit Ethernet and other interconnect that is backward compatible with Category 5 cable, Cat-5e and Cat-3.

cat-6 features more stringent specifications for crosstalk and system noise. The cable standard is suitable for 10BASE-T / 100BASE-TX and 1000BASE-T (Gigabit Ethernet) connections.

The cable contains four twisted copper wire pairs, just like earlier copper cable standards, although each twisted pair is made up of slightly larger 23 gauge copper wire as opposed to Cat 5's 24 gauge wire. When used as a patch cable, Cat-6 is normally terminated in RJ-45 electrical connectors. If components of the various cable standards are intermixed, the performance of the signal path will be limited to that of the lowest category. The

distance without losing data is 220m.

RJ-45 Wiring

Wall Plates

The standards specify that two jacks should be placed at each outlet location. The jacks can be on the same wall plate. A separate Category 5 wire should be run from the telecommunications closet to each jack. If one jack and wire system fails at the location, there is a second as a reserve. This avoids the need for immediate repair to maintain service at that location. It is recommended that a minimum of two wall outlet locations be installed in each classroom. One telecommunications outlet can be associated with voice and/or video; the other can be associated with data.

Distances

The standards specify that the maximum distance of any cable run shall be 90 meters (295 feet) as measured from the termination of the cable in the telecommunications closet to the wall outlet. An allowance is made for an additional maximum length of 3 meters (9.8 ft.) of cable from the wall outlet to the work station.

If other wire types exist within the building, they can be joined to the new installation by means of media changing devices. Other types of cables and mixed cable systems will have different distance standards. Media changing devices should provide distance guidelines for their use. The general specifications for a LAN using Ethernet protocols:

10Base2 is 10MHz Ethernet running over thin, 50 Ohm baseband coaxial cable. 10Base2 also is referred to as Thin Ethernet or Thin-net. 10Base2 is limited to 185 meters (607 ft.) per unrepeated cable segment. The minimum distance between T-connectors is 1.6 feet. Terminators must be used at both ends of a segment. One of the ends must be grounded.

10Base5 is 10MHz Ethernet running over standard (thick) 50 Ohm baseband coaxial cabling. 10Base5 is commonly call Thick Ethernet. 10Base5 is limited to 500 meters (1,640 ft.) per unrepeated cable segment.

10BaseF is 10MHz Ethernet running over fiber-optic cabling. 10BaseF depends on the signaling technology and medium used but can go up to 2 kilometers. 10BaseF networks are star-wired, so there is no minimum distance requirement between devices because devices cannot be connected serially.

10BaseT is 10MHz Ethernet running over unshielded, twisted-pair cabling. 10BaseT is accepted to have a maximum run of 100-115 meters, but is based on signal loss in Dbs (11.5db maximum loss source to destination). 10BaseT networks are star-wired, so there is no minimum distance requirement between devices as described in this document because devices cannot be connected serially.

Repeaters can make cable runs longer, but there are rules for repeaters. For an Ethernet LAN, there can be no more than five repeated segments, nor more than four repeaters between any two Ethernet stations. Of the five

cable segments, only three can be populated. This is referred to as the "5-4-3" rule (5 segments, 4 repeaters, 3 populated segments). The "5-4-3" rule is independent of the type of cable used on any one segment. If a type of cable is consistent throughout a network then theoretical distance limits equal five times the single segment length. If a network contains mixed cable, then distances are estimates and depend heavily on the bridging devices between segments.

4.1 Physical Layer Summary

The following table provides a summary of the various physical layer specifications defined for Ethernet. The maximum cable segment lengths listed for half-duplex operation are valid for networks with only one repeater or repeating hub. Further analysis is required to determine the maximum cable segment lengths for multi-segment networks with more than one repeater. The maximum segment lengths listed for full-duplex operation are valid regardless of the size of the network.

Standard

Standard
First
Released

Data
Rate

Top-
ology

Medium

Maximum Cable Segment
Length in Meters

Half-Duplex

Full-Duplex

10Base5

DIX-1980,
802.3-1983

10Mb/s

Bus

single 50-ohm coaxial cable (thick Ethernet) (10mm thick)

500

n/a

10Base2

802.3a-1985

10Mb/s

Bus

single 50-ohm RG 58 coaxial cable (thin Ethernet) (5mm thick)

185

n/a

10Broad36

802.3b-1985

10Mb/s

Bus

single 75-ohm CATV broadband cable

1800

n/a

FOIRL

802.3d-1987

10Mb/s

Star

two optical fibers

1000

>1000

1Base5

802.3e-1987

1Mb/s

Star

two pairs of twisted telephone cable

250

n/a

10Base-T

802.3i-1990

10Mb/s

Star

two pairs of 100-ohm Category 3 or better UTP cable

100

100

10Base-FL

802.3j-1993

10Mb/s

Star

two optical fibers

2000

>2000

10Base-FB

802.3j-1993

10Mb/s

Star

two optical fibers

2000

n/a

10Base-FP

802.3j-1993

10Mb/s

Star

two optical fibers

1000

n/a

100Base-TX

802.3u-1995

100Mb/s

Star

two pairs of 100-ohm Category 5 UTP cable

100

100

100Base-FX

802.3u-1995

100Mb/s

Star

two optical fibers

412

2000

100Base-T4

802.3u-1995

100Mb/s

Star

four pairs of 100-ohm Category 3 or better UTP cable

100

n/a

100Base-T2

802.3y-1997

100Mb/s

Star

two pairs of 100-ohm Category 3 or better UTP cable

100

100

1000Base-LX

802.3z-1998

1Gb/s

Star

long wavelength laser (1300nm) over:
- 62.5um multi-mode fiber
- 50um multi-mode fiber
- 10um single mode fiber


316
316
316


550
550
5000

1000Base-SX

802.3z-1998

1Gb/s

Star

short wavelength laser (850nm) over:
- 62.5um multi-mode fiber
- 50um multi-mode fiber


275
316


275
550

1000Base-CX

802.3z-1998

1Gb/s

Star

specialty shielded balanced copper jumper cable assemblies ("twinax" or "short haul copper")

25

25

1000Base-T

802.3ab-1999

1Gb/s

Star

four pairs of 100-ohm Category 5 or better cable

100

100

4.2 10 Mb/s Physical Layers

4.2.1 10Base5

10Base5 is the original Ethernet system that supports a 10 Mb/s transmission rate over "thick" (10mm) coaxial cable. The "10Base5" identifier is shorthand for 10 Mb/s transmission rate, the baseband form of transmission, and the 500 meter maximum supported segment length.

Thick Ethernet coaxial cabling includes a "mark" every 2.5 meters to indicate proper placement of the 10Base5 transceivers (or MAUs) used to connect stations to the network. Transceivers may be placed at any multiple of 2.5 meter intervals. This minimizes signal reflections that may degrade the transmission quality of the cable segment. The outer jacket of Thick Ethernet cables is typically a bright color (often yellow) with black bands at 2.5 meter intervals to mark valid transceiver placement points.

10Base5 transceivers are attached through a clamp that makes physical and electrical contact with the cable. They are also called "transceiver taps" because they are connected through a process known as "tapping" that drills a hole in the cable to allow electrical contact to be made. The transceivers are called "non-intrusive" taps because the connection can be made on an active network without disrupting traffic flow.

Stations attach to the transceiver through a transceiver cable that is also called an "attachment unit interface", or AUI. Typically computer stations that attach to 10Base5 include an Ethernet "network interface card" (NIC) or "adapter card" with a 15-pin AUI connector. The transceiver cable connects between the 15-pin AUI connector on the NIC to another 15-pin connector on the transceiver. The standard allows the transceiver cable to be up to 50 meters in length. This permits stations to be located up to 50 meters from the coaxial cable segment.

The standard allows a 10Base5 coaxial cable segment to be up to 500 meters in length. Up to 100 transceivers may be connected to a single segment at any multiple of 2.5 meters apart. A 10Base5 segment may consist of a single continuous section of cable, or be assembled from multiple cable sections that are attached end to end. If multiple cable sections are used, it can result in "impedance mismatches" that are caused by slight differences in the impedance of each cable section. When excessive, these mismatches can cause signal reflections that result in bit errors and discarded frames. Segments with multiple sections are often built with cable that comes from a

single spool. This ensures each section of the cable segment will have consistent impedance since it was built by one manufacturer, at one time, using the same equipment. Cable segments can be joined at any point along their length and are not restricted to 2.5 meter intervals like transceivers.

Multiple 10Base5 segments may be connected through "repeaters" to form a larger network that still consists of a single collision domain. A repeater regenerates the signal by receiving it from one cable segment and then re-transmitting it at its original strength over all the other cable segments. The 10Base5 standard permits up to five cable segments, and thus up to four repeaters, in the path between two stations. Up to three of the segments may be coaxial cable segments (up to 1500 meters), and the other two segments must be point to point inter-repeater links (up to 1000 meters). Each end of the three coaxial cable segments may have a 50 meter AUI cable (up to 300 meters). This results in a maximum total network span of 2800 meters.

10Base5 coaxial cable segments are built using "N-type" connectors. Each end of a segment must have a N-type coaxial connector with N-type 50-ohm terminators installed. Two sections of a segment are interconnected using two N-type coaxial connectors that are mated together through a N-type barrel connector. Long 10Base5 segments typically have one or more barrel connectors to allow the segment to be split for purposes of problem isolation. For safety reasons, the standard specifies that a cable segment should be connected to earth ground at one and only one point. This may be done at the terminator at the end of the cable, or at a barrel connector where two segments are joined.

10Base5 Advantages: 1) very reliable when properly installed, and 2) new stations easily added by tapping into existing cable segment.
10Base5 Disadvantages: 1) thick, heavy, and inflexible cable makes installation a challenge, 2) bus topology makes problem isolation difficult, and 3) the coaxial medium does not support higher speed Ethernet standards.

10Base5 Facts

Transmission Rate

10 Mb/s (full-duplex not supported)

Cable Type

A single "thick" (10mm) coaxial cable with 50 2 ohms impedance,
Supports bend radius of 2.54 cm (10 inches),
Belden part numbers 9880 (PVC) & 89880 (plenum rated)

Maximum Segment Length

500 meters (1640 feet)

Maximum Transceiver Cable (AUI) Length

50 meters (164 feet)

Maximum Number of Transceivers per Segment

100

Connecter Technology

N-type coaxial connectors, barrel connectors, & terminators

Signal Encoding

Manchester encoding

4.2.2 10Base2

10Base2 supports a 10 Mb/s transmission rate over "thin" (5mm) coaxial cable. It is also known as "thin Ethernet", or "cheapernet". It was the first new variety of physical medium to be adopted after the original thick Ethernet standard.

The 10Base2 standard is similar in many ways to 10Base5. Both standards implement a bus topology using a 50-ohm coaxial cable. They both implement the same signal encoding, signal transmission, and collision detection mechanisms. The thinner cable used by 10Base2 has the advantages of being cheaper, lighter, more flexible, and easier to install than the thick cable used by 10Base5. However the thin cable has the disadvantage that its transmission characteristics are not as good. It supports only a 185 meter maximum segment length (vs. 500 meters for 10Base5) and a maximum of 30 stations per cable segment (vs. 100 for 10Base5).

The spacing between stations is not critical with the 10Base2 specification, but it does require that a minimum of 0.5 meters of cable separate any two stations. This spacing acts to minimize signal reflections caused by the cable connections.

Transceivers are connected to the cable segment through a "BNC Tee" connector, and not through "tapping" as with 10Base5. As the name implies, the BNC Tee connector is shaped like the letter "T". The horizontal part of the "T" includes female connectors that mate with the male BNC coaxial connectors on each end of the attaching cable sections. The vertical part of the "T" includes a male BNC connector that either plugs directly into the Ethernet network interface card (NIC) in the computer station, or to an external thin Ethernet transceiver that is then attached to the NIC through a standard AUI cable. If stations are removed from the network, the "T" connector is removed and replaced with a "BNC Barrel" connector that provides a straight through connection.

Each end of a 10Base2 coaxial segment must be terminated with a BNC 50-ohm terminator. For safety reasons,

a ground wire should connect the segment to earth ground at one point, typically at the terminator on the end of the segment.

Unlike 10Base5, the 10Base2 standard optionally allows the transceiver (or MAU) function to be integrated directly into the network interface card. This further reduces cost by eliminating the need for the external transceiver component and AUI cable. It does require however that the cable segment be routed in direct proximity of the computer station as the "T" connector must be plugged directly into the female BNC connector on network interface card. No cable "stub" is allowed between the NIC and the "T" connector. 10 Mb/s Ethernet NICs commonly include both a BNC connector and AUI connector to allow them to be attached directly to a 10Base2 "T" connector, or to an external transceiver through an AUI cable.

Two wiring topologies are supported by 10Base2. The BNC Tee connectors easily support a "daisy chain" topology where the cable segment is routed directly from one computer to the next. Terminators are installed on the unused "T" connector at each end of the segment. The other topology is "point-to-point" where the cable segment attaches only a single station to a 10Base-2 repeater. The "point-to-point" topology is useful in office environments where the structure of the building makes it impractical to daisy chain multiple computers together. The cable segment is terminated at the computer station on one end, and routed to a repeater in a wiring closet on the other end.

10Base2 Advantages: 1) thinner cable makes installation easier than 10Base-5, and 2) cost is reduced by eliminating the external transceivers required by 10Base5.
10Base2 Disadvantages: 1) daisy chained segments are unreliable and difficult to troubleshoot, and 2) daisy chained segments can be difficult to route in an office environment, and 3) the coaxial medium does not support higher speed Ethernet standards.

10Base2 Facts

Transmission Rate

10 Mb/s (full-duplex not supported)

Cable Type

A single "thin" (5mm) coaxial cable with 50 2 ohms impedance,
RG58A/U or RG58C/U,
Supports bend radius of 5 cm (2 inches),
Belden part numbers 9907 (PVC) & 89907 (plenum rated)

Maximum Segment Length

185 meters (606.9 feet)

Minimum Spacing Between Stations

0.5 meters

Maximum Number of Transceivers per Segment

30

Connecter Technology

BNC Tee coaxial connectors, barrel connectors, & terminators

Signal Encoding

Manchester encoding

4.2.3 10Base-T

10Base-T supports a 10 Mb/s transmission rate over two pairs of Category 3 or better telephone twisted pair cabling, also known as "voice grade" twisted pair. The widespread use of twisted pair wiring has made 10Base-T the most popular version of Ethernet.

10Base-T uses one pair of wires for transmitting data, and the other pair for receiving data. The two pairs of wires are bundled into a single cable that may often include two additional pairs of wires which are unused for 10Base-T. Each end of the cable is terminated with an 8 position RJ-45 connector, or "jack".

All 10Base-T connections are point-to-point. This implies that a 10Base-T cable can have a maximum of two Ethernet transceivers (or MAUs), with one at each end of the cable. One end of the cable is typically attached to a 10Base-T "repeating hub". The other end is attached directly to a computer station's network interface card (NIC), or an external 10Base-T transceiver. The transceiver function is integrated into most 10Base-T NICs allowing the cable to be plugged directly into an RJ-45 connector on the NIC without any external components or termination. The AUI interface on older NICs may be used attached to a 10Base-T network through an external transceiver.

Two 10Base-T NICs may be directly attached to each other without a 10Base-T repeating hub. In this case a special "crossover cable" is required that attaches the transmit pair of one station to the receive pair of the other station, and vice versa. When attaching a NIC to a repeating hub, a normal "straight through" cable is used and the cross over function is performed inside the repeating hub.

The target segment length for 10Base-T with Category 3 wiring is 100 meters. Longer segments can be accommodated as long as signal quality specifications are met. Higher quality cabling such as Category 5 wiring may be able to achieve longer segment lengths in the order of 150 meters while still maintaining the signal quality required by the standard.

The point-to-point cable connections of 10Base-T result in a "star" topology for the network. A star topology consists of a central hub with point-to-point links that appear to radiate out from the center like light from a star. The star topology simplifies maintenance, allows for faster troubleshooting, and isolates cable problems to a single link. 10Base-T is well suited for use in structured cabling systems. Structured cabling systems locate hubs in central wiring closets. Cables fanout to wall outlets in each office. In the office, a "patch" cable connects the computer station to the wall outlet.

10Base-T transceivers continually monitor the receive data path for activity to check that the link is working correctly. During periods when the network is idle, transceivers send a "link pulse" to each other as a means of verifying the integrity of the twisted pair connections. 10Base-T transceivers may optionally provide a "link light" that remains lit as long as the transceiver receives frames or link pulses from the other end of the segment. If the link lights are "on" at both ends of the segment, then you have an indication that the segment is wired correctly. This function is known as a "link integrity test".

The independent transmit and receive paths of the 10Base-T media allow the full-duplex mode of operation to be optionally supported. To support full-duplex mode, both the NIC and the hub must be capable of, and be configured for, full-duplex operation.

10Base-T Advantages: 1) the star wiring topology supports easier maintenance and troubleshooting, 2) twisted pair wiring is inexpensive and widely used, and 3) optionally supports full-duplex operation.
10Base-T Disadvantages: 1) 10Base5 and 10Base2 support longer segment lengths.

10Base-T Facts

Transmission Rate

10 Mb/s (20 Mb/s in optional full-duplex mode)

Cable Type

two pairs of Category 3 or better unshielded twisted pair (UTP) cabling,
also known as voice grade or telephone twisted pair cabling,
100-ohm impedance rating

Maximum Segment Length

100 meters (328 feet)

Maximum Number of Transceivers per Segment

2

Connecter Technology

RJ-45 style modular jack (8-pins)

Signal Encoding

Manchester encoding

4.2.4 10Broad36

10Broad36 supports a 10 Mb/s transmission rate over a "broadband" cable system. The "36" in the name refers to the 3600 meter total span supported between any two stations.

The broadband cable used with 10Broad36 is the same inexpensive coaxial cable used in cable TV (CATV) transmission systems. Broadband cable systems support transmission of multiple services over a single cable by dividing the bandwidth into separate frequencies, with each frequency assigned to a different service. This technique is used in cable TV transmission systems to transmit multiple channels over a single cable. Each channel uses a different frequency range. This capability can allow 10Broad36 share a single cable with other services such as video.

Broadband cable also has the advantage of being able to support transmission of signals over longer distances than the baseband coaxial cable used with 10Base5 and 10Base2. Single 10Broad36 segments can be as long as 1800 meters. All 10Broad36 networks are terminated by a "head end" device. The head end can be at the end of a single segment, or at the root of multiple segments. With multiple segments the broadband cable media can span a total distance of up to 3600 meters. 10Broad36 supports attachment of stations through transceivers that are physically and and electrically attached to the broadband cable. Computers attach to the transceivers through an AUI cable that can be up to 50 meters in length. This technically allows the maximum total distance spanned between two stations to be up to 3700 meters.

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