B Cables
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.
Adjusting Existing Category 5 Cabling to Run 1000BASE-T
If your existing Category 5 installation does not meet one of the test parameters for 1000BASE-T, there are basically three measures that can be applied to try and correct the problem:
1.Replace any Category 5 patch cables with high-performance Category 5e or Category 6 cables.
2.Reduce the number of connectors used in the link.
3.Reconnect some of the connectors in the link.
Fiber Standards
The International Telecommunication Union (ITU-T) has standardized various fiber types for data networks. These are summarized in the following table.
Table B-3 Fiber Standards
ITU-T | Description | Application |
Standard | | |
| | |
G.651 | Multimode Fiber | Short-reach connections in the |
| 50/125-micron core | 1300-nm or 850-nm band |
| | |
G.652 | Non-Dispersion-Shifted | Longer spans and extended reach. |
| FiberSingle-mode, 9/125-micron core | Optimized for operation in the |
| | 1310-nm band. but can also be used |
| | in the 1550-nm band |
| | |
G.652.C | Low Water Peak | Longer spans and extended reach. |
| Non-Dispersion-Shifted Fiber | Optimized for wavelength-division |
| Single-mode, 9/125-micron core | multiplexing (WDM) transmission |
| | across wavelengths from 1285 to |
| | 1625 nm. The zero dispersion |
| | wavelength is in the 1310-nm region. |
| | |
