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700 Series Managed Switch User’s Guide for Software v2.1
Cabling Guidelines B-5
SM-10004-02
Note: Flat “silver satin” telephone cable may have the same RJ-45 plug. However, using telephone
cable results in excessive collisions, causing the attached port to be partitioned or disconnected
from the network.
Using 1000BASE-T Gigabit Ethernet over Category 5 Cable
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.