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Cisco CRS-1 Carrier Routing System SIP and SPA Hardware Installation Guide
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Chapter 3 Overview: Cisco CRS-1 Shared Port Adapters
5-Port Gigabit Ethernet SPA Overview
SFP-GE-L Modules
The 1000BASE-LX/LH (long-wavelength/long-haul) module interfaces fully comply with the
IEEE 802.3z 1000BASE-LX standard. However, their higher optical quality allows them to reach
6.2 miles (10 km) over single-mode fiber (SMF) versus the 3.1 miles (5 km) specified in the standard.
SFP-GE-Z Modules
The 1000BASE-ZX (extended wavelength) module operates on ordinary single-mode fiber-optic link
spans of up to 49.7 miles (80 km). Link spans of up to 62.1 miles (100 km) are possible using premium
single-mode fiber or dispersion-shifted single-mode fiber. (Premium single-mode fiber has a lower
attenuation per unit length than ordinary single-mode fiber; dispersion-shifted single-mode fiber has
both lower attenuation and less dispersion.)
The 1000BASE-ZX module must be coupled to single-mode fiber-optic cable, which is the type of cable
typically used in long-haul telecommunications applications. The 1000BASE-ZX module does not
operate correctly when coupled to multimode fiber, and it is not intended to be used in environments in
which multimode fiber is frequently used (for example, building backbones or horizontal cabling).
The 1000BASE-ZX module is intended to be used as a Physical Medium Dependent (PMD) component
for Gigabit Ethernet interfaces found on various switch and router products. It operates at a signaling
rate of 1250 Mbaud, transmitting and receiving 8B/10B encoded data.
When shorter lengths of single-mode fiber are used, it may be necessary to insert an inline optical
attenuator in the link to avoid overloading the receiver. Use the following guidelines:
•
Insert a 10-dB inline optical attenuator between the fiber-optic cable plant and the receiving port on
the 1000BASE-ZX module at each end of the link whenever the fiber-optic cable span is less than
15.5 miles (25 km).
•
Insert a 5-dB inline optical attenuator between the fiber-optic cable plant and the receiving port on
the 1000BASE-ZX module at each end of the link whenever the fiber-optic cable span is equal to or
greater than 15.5 miles (25 km) but less than 31 miles (50 km).
SFP-GE-T Modules
The SFP-GE-T (1000BASE-T copper SFP module) provides full-duplex Gigabit Ethernet connectivity
to high-end workstations and between wiring closets over an existing copper network infrastructure. The
SFP-GE-T maximum cabling distance is 328 feet (100 m).
SFP Module Cabling and Connection Equipment
Table 3-18
provides cabling specifications for the SFP modules that can be installed on the 5-Port
Gigabit Ethernet SPA. Note that all SFP ports have LC-type connectors.
The minimum cable distance for the SFP-GE-S is 6.5 feet (2 m), and the minimum link distance for the
SFP-GE-Z is 6.2 miles (10 km) with an 8-dB attenuator installed at each end of the link. Without
attenuators, the minimum link distance for the SFP-GE-Z is 24.9 miles (40 km).
