10/100Base-X And 1000Base-Tx Reach - Avaya 8800 Planning And Engineering, Network Design

Table 8: Spectral widths and link lengths assuming an average fiber of 1.0 ps/(nm-km)
Spectral width (nm)
1
10
50
If your fiber chromatic dispersion is over the limit, you can use chromatic dispersion compensating
devices, for example, dispersion compensating optical fiber.
Polarization mode dispersion
Before you put an XFP into service for a long fiber, ensure that the fiber PMD is within the ITU
recommendations. The ITU recommends that the total PMD of a fiber link not exceed 10% of the bit
period. At 10 Gbit/s, this means that the total PMD of the fiber must not exceed 10 picoseconds (ps).
At 40 Gbit/s, the total PMD of the link must not exceed 2.5 ps. For new optical fiber, manufacturers
have taken steps to address fiber PMD. However, older, existing fiber plant may have high PMD
values. For long optical links over older optical fibers, measure the PMD of the fiber proposed to
carry 10 Gbit/s.
The following table shows the PMD limits.
Table 9: PMD limits
Data rate Maximum PMD of link
(picoseconds)
1 Gbit/s 100
10 Gbit/s 10
40 Gbit/s 2.5
The dispersion of a fiber can change over time and with temperature change. If you measure fiber
dispersion, measure it several times at different temperatures to determine the worst-case value. If
you do not consider dispersion in your network design, you may experience an increase in the BER
of your optical links.
If no PMD compensating devices are available and the proposed fiber is over the PMD limit, use a
different optical fiber.

10/100BASE-X and 1000BASE-TX reach

The following tables list maximum transmission distances for 10/100BASE-X and 1000BASE-TX
Ethernet cables.
June 2016
Maximum link length (km)
1000
100
20
Maximum PMD coefficient
based on a 100 km-long fiber
span (ps/sqrt-km)
10
1.0
0.25
Planning and Engineering — Network Design
Comments on this document? infodev@avaya.com
10/100BASE-X and 1000BASE-TX reach
Maximum PMD coefficient
based on a 400 km-long fiber
span (ps/sqrtkm)
5.0
0.5
0.125
35