LevelOne GTL-2691, Руководство по установке

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B-4
Cables
B
Cable Testing for Existing Category 5 Cable
Installed Category 5 cabling must pass tests for Attenuation, Near-End Crosstalk
(NEXT), and Far-End Crosstalk (FEXT). This cable testing information is specified in
the ANSI/TIA/EIA-TSB-67 standard. Additionally, cables must also pass test
parameters for Return Loss and Equal-Level Far-End Crosstalk (ELFEXT). These
tests are specified in the ANSI/TIA/EIA-TSB-95 Bulletin, “The Additional
Transmission Performance Guidelines for 100 Ohm 4-Pair Category 5 Cabling.”
Note that when testing your cable installation, be sure to include all patch cables
between switches and end devices.
10GBASE-T Pin Assignments
All 10GBASE-T ports support automatic MDI/MDI-X operation, so you can use
straight-through cables for all network connections to PCs or servers, or to other
switches or hubs.
Table B-2, “1000BASE-T and 10GBASE-T MDI and MDI-X Port Pinouts,” on
page B-3 shows the 10GBASE-T MDI and MDI-X port pinouts. These ports
require that all four pairs of wires be connected. Note that for 10GBASE-T
operation, all four pairs of wires are used for both transmit and receive.
Use 100-ohm Category 5e, 6, 6a or 7 twisted-pair cable for 10GBASE-T
connections as specified in Table 4-1, “Maximum 10GBASE-T Gigabit Ethernet
Cable Length,” on page 4-7. Also be sure that the length of any twisted-pair
connection does not exceed the lengths specified in this table.
Cable Testing for Category 6 and 6a Cable
Installed Category 6 cabling must pass tests specified in the ANSI/TIA-TSB-155 and
ISO/IEC 24750 standards. Category 6a cables must also pass test parameters
specified in the ANSI/TIA/EIA-568-B.2-10 standard. Methods of mitigating of alien
crosstalk in Category 6 and 6a cable is covered in ANSI/TIA-TSB-155 and ISO/IEC
TR24750.
Note that when testing your cable installation, be sure to include all patch cables
between switches and end devices.
Adjusting Existing Cabling for 1000BASE-T and 10GBASE-T
If your existing cable installation does not meet one of the test parameters for
1000BASE-T or 10GBASE-T, there are basically three measures that can be applied
to try and correct the problem:
1. For 1000BASE-T, replace any Category 5 patch cables with high-performance
Category 5e or Category 6 cables. For 10GBASE-T, replace any Category 5e
patch cables with Category 6, augmented Category 6a, or Category 7 cables.