Netgear FSM750S FSM750S Reference Manual - Page 122

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Using 1000BASE-T Gigabit Ethernet over Category 5 Cable Overview When using the new 1000BASE-T standard, the limitations of cable installations and the steps necessary to ensure optimum performance must be considered. The most important components in your cabling system are patch panel connections, twists of the pairs at connector transition points, the jacket around the twisted-pair cable, bundling of multiple pairs on horizontal runs and punch down blocks. All of these factors affect the performance of 1000BASE-T technology if not correctly implemented. The following sections are designed to act as a guide to correct cabling for 1000BASE-T. Cabling The 1000BASE-T product is designed to operate over Category 5 cabling. To further enhance the operation, the cabling standards have been amended. The latest standard is Category 5e, which defines a higher level of link performance than is available with Category 5 cable. If installing new cable, we recommend using Category 5e cable, since it costs about the same as Category 5 cable. If using the existing cable, be sure to have the cable plant tested by a professional who can verify that it meets or exceeds either ANSI/EIA/TIA-568-A:1995 or ISO/IEC 11801:1995 Category 5 specifications. Length The maximum distance limitation between two pieces of equipment is 100 m, as per the original Ethernet specification. The end-to-end link is called the "channel." TSB-67 defines the "Basic Link" which is the portion of the link that is part of the building infrastructure. This excludes patch and equipment cords. The maximum basic link length is 295 feet (90 m). Return Loss Return loss measures the amount of reflected signal energy resulting from impedance changes in the cabling link. The nature of 1000BASE-T renders this measurement very important; if too much energy is reflected back on to the receiver, the device does not perform optimally. Unlike 10BASE-T and 100BASE-TX, which use only two of the four pairs of wires within the Category 5, 1000BASE-T uses all four pairs of the twisted pair. Make sure all wires are tested  this is important. Factors that affect the return loss are: The number of transition points, as there is a connection via an RJ-45 to another connector, a patch panel, or device at each transition point. Removing the jacket that surrounds the four pairs of twisted cable. It is highly recommended that, when RJ-45 connections are made, this is minimized to 1-1/4 inch (32 mm). Untwisting any pair of the twisted-pair cabling. It is important that any untwisting be minimized to 3/8 inch (10 mm) for RJ-45 connections. Cabling or bundling of multiple Category 5 cables. This is regulated by ANSI/EIA/TIA-568A-3. If not correctly implemented, this can adversely affect all cabling parameters. Near End Cross Talk (NEXT) This is a measure of the signal coupling from one wire to another, within a cable assembly, or among cables within a bundle. NEXT measures the amount of cross-talk disturbance energy that is detected at the near end of the link - the end where the transmitter is located. NEXT measures the amount of energy that is "returned" to the sender end. The factors that affect NEXT and cross talk are exactly the same as outlined in the Return Loss section. The cross-talk performance is directly related to the quality of the cable installation. Patch Cables When installing your equipment, replace old patch panel cables that do not meet Category 5e specifications. As pointed out in the NEXT section, this near end piece of cable is critical for successful operation. Conclusion For optimum performance of your 1000BASE-T product, it is important to fully qualify your cable installation and ensure it meets or exceeds ANSI/EIA/TIA-568-A:1995 or ISO/IEC 11801:1995 Category 5 specifications. Install Category 5e cable where possible, including patch panel cables. Minimize transition points, jacket removal, and untwist lengths. Bundling of cables must be properly installed to meet the requirements in ANSI/EIA/TIA-568A-3. Page 121 of 121

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Page 121 of 121
Using 1000BASE-T Gigabit Ethernet over Category 5 Cable
Overview
When using the new 1000BASE-T standard, the limitations of cable installations and the steps necessary to ensure optimum performance must be
considered. The most important components in your cabling system are patch panel connections, twists of the pairs at connector transition points,
the jacket around the twisted-pair cable, bundling of multiple pairs on horizontal runs and punch down blocks. All of these factors affect the
performance of 1000BASE-T technology if not correctly implemented. The following sections are designed to act as a guide to correct cabling for
1000BASE-T.
Cabling
The 1000BASE-T product is designed to operate over Category 5 cabling. To further enhance the operation, the cabling standards have been
amended. The latest standard is Category 5e, which defines a higher level of link performance than is available with Category 5 cable.
If installing new cable, we recommend using Category 5e cable, since it costs about the same as Category 5 cable. If using the existing cable, be
sure to have the cable plant tested by a professional who can verify that it meets or exceeds either ANSI/EIA/TIA-568-A:1995 or ISO/IEC
11801:1995 Category 5 specifications.
Length
The maximum distance limitation between two pieces of equipment is 100 m, as per the original Ethernet specification. The end-to-end link is called
the “channel.”
TSB-67 defines the “Basic Link” which is the portion of the link that is part of the building infrastructure. This excludes patch and equipment cords.
The maximum basic link length is 295 feet (90 m).
Return Loss
Return loss measures the amount of reflected signal energy resulting from impedance changes in the cabling link. The nature of 1000BASE-T
renders this measurement very important; if too much energy is reflected back on to the receiver, the device does not perform optimally.
Unlike 10BASE-T and 100BASE-TX, which use only two of the four pairs of wires within the Category 5, 1000BASE-T uses all four pairs of the
twisted pair. Make sure all wires are tested
this is important.
Factors that affect the return loss are:
The number of transition points, as there is a connection via an RJ-45 to another connector, a patch panel, or device at each transition point.
Removing the jacket that surrounds the four pairs of twisted cable. It is highly recommended that, when RJ-45 connections are made, this is
minimized to 1-1/4 inch (32 mm).
Untwisting any pair of the twisted-pair cabling. It is important that any untwisting be minimized to 3/8 inch (10 mm) for RJ-45 connections.
Cabling or bundling of multiple Category 5 cables. This is regulated by ANSI/EIA/TIA-568A-3. If not correctly implemented, this can adversely affect
all cabling parameters.
Near End Cross Talk (NEXT)
This is a measure of the signal coupling from one wire to another, within a cable assembly, or among cables within a bundle. NEXT measures the
amount of cross-talk disturbance energy that is detected at the near end of the link — the end where the transmitter is located. NEXT measures the
amount of energy that is “returned” to the sender end. The factors that affect NEXT and cross talk are exactly the same as outlined in the Return
Loss section. The cross-talk performance is directly related to the quality of the cable installation.
Patch Cables
When installing your equipment, replace old patch panel cables that do not meet Category 5e specifications. As pointed out in the NEXT section,
this near end piece of cable is critical for successful operation.
Conclusion
For optimum performance of your 1000BASE-T product, it is important to fully qualify your cable installation and ensure it meets or exceeds
ANSI/EIA/TIA-568-A:1995 or ISO/IEC 11801:1995 Category 5 specifications. Install Category 5e cable where possible, including patch panel
cables. Minimize transition points, jacket removal, and untwist lengths. Bundling of cables must be properly installed to meet the requirements in
ANSI/EIA/TIA-568A-3.