Netgear FSM750S – 48-Port 10/100 Mbps Managed Stackable Switch with Gigabit Ports Manuale Di Riferimento
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APPENDIX F: CABLING GUIDELINES
This appendix provides specifications for cables used with the NETGEAR Model FSM726S or FSM750S Managed Stackable Switch.
Fast Ethernet Cable Guidelines
Fast Ethernet uses UTP cable, as specified in the IEEE 802.3u standard for 100BASE-TX.The specification requires Category 5 UTP cable
consisting of either two-pair or four-pair twisted insulated copper conductors bound in a single plastic sheath. Category 5 cable is certified up to 100
MHz bandwidth. 100BASE-TX operation uses one pair of wires for transmission and the other pair for receiving and for collision detection.
When installing Category 5 UTP cabling, use the following guidelines to ensure that your cables perform to the following specifications:
Certification
Make sure that your Category 5 UTP cable has completed the Underwriters’ Laboratories (UL) or Electronic Testing Laboratories (ETL) certification
process.
Termination method
To minimize cross-talk noise, maintain the twist ratio of the cable up to the point of termination; untwist at any RJ-45 plug or patch panel should not
exceed 0.5 inch (1.5 cm).
consisting of either two-pair or four-pair twisted insulated copper conductors bound in a single plastic sheath. Category 5 cable is certified up to 100
MHz bandwidth. 100BASE-TX operation uses one pair of wires for transmission and the other pair for receiving and for collision detection.
When installing Category 5 UTP cabling, use the following guidelines to ensure that your cables perform to the following specifications:
Certification
Make sure that your Category 5 UTP cable has completed the Underwriters’ Laboratories (UL) or Electronic Testing Laboratories (ETL) certification
process.
Termination method
To minimize cross-talk noise, maintain the twist ratio of the cable up to the point of termination; untwist at any RJ-45 plug or patch panel should not
exceed 0.5 inch (1.5 cm).
Category 5 Cable
Category 5 distributed cable that meets ANSI/EIA/TIA-568-A building wiring standards can be a maximum of 328 feet (ft) or 100 meters (m) in
length, divided as follows:
length, divided as follows:
20 ft (6 m) between the hub and the patch panel (if used)
295 ft (90 m) from the wiring closet to the wall outlet
10 ft (3 m) from the wall outlet to the desktop device
The patch panel and other connecting hardware must meet the requirements for 100 Mbps operation (Category 5). Only 0.5 inch (1.5 cm) of untwist
in the wire pair is allowed at any termination point.
in the wire pair is allowed at any termination point.
Category 5 Cable Specifications
Ensure that the fiber cable is crossed over to guarantee link.
Table F-1 lists the electrical requirements of Category 5 UTP cable.
Table F-1 lists the electrical requirements of Category 5 UTP cable.
Table F-1. Electrical Requirements of Category 5 Cable
Specifications
Category 5 Cable Requirements
Number of pairs
Four
Impedance 100
Ω ± 15%
Mutual capacitance at 1 KHz
≤5.6 nF per 100 m
Maximum attenuation
(dB per 100 m, at 20° C)
(dB per 100 m, at 20° C)
at 4 MHz: 8.2
at 31 MHz: 11.7
at 100 MHz: 22.0
at 31 MHz: 11.7
at 100 MHz: 22.0
NEXT loss (dB minimum)
at 16 MHz: 44
at 31 MHz: 39
at 100 MHz: 32
at 31 MHz: 39
at 100 MHz: 32
Twisted Pair Cables
For two devices to communicate, the transmitter of each device must be connected to the receiver of the other device. The crossover function is
usually implemented internally as part of the circuitry in the device. Computers and workstation adapter cards are usually media-dependent
interface ports, called MDI or uplink ports. Most repeaters and switch ports are configured as media-dependent interfaces with built-in crossover
ports, called MDI-X or normal ports. Auto Uplink technology automatically senses which connection, MDI or MDI-X, is needed and makes the right
connection.
Figure F-1 illustrates straight-through twisted pair cable.
usually implemented internally as part of the circuitry in the device. Computers and workstation adapter cards are usually media-dependent
interface ports, called MDI or uplink ports. Most repeaters and switch ports are configured as media-dependent interfaces with built-in crossover
ports, called MDI-X or normal ports. Auto Uplink technology automatically senses which connection, MDI or MDI-X, is needed and makes the right
connection.
Figure F-1 illustrates straight-through twisted pair cable.