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Catalyst 2984G, 2948G-GE-TX, and 2980G Switch Hardware Installation Guide
78-6286-05
Chapter 4 Configuring the Gigabit Ethernet Ports
Connecting To an SFP Module
The restrictions are that each port must match the wave-length specifications on
the other end of the cable, and the cable must not exceed the recommended cable
length for reliable communications. Table 4-5 lists these recommendations.
Note For information about the Coarse Wave Division Multiplexing (CWDM), refer to
the Cisco CWDM GBIC and CWDM SFP Installation Note.
The 1000BASE-T (copper) SFP module is used to establish a Gigabit Ethernet
connection through a Category 5 Category 5 cable.
Use only Cisco SFP modules on the Catalyst 2948G-GE-TX switch. Each SFP
module has an internal serial EEPROM that is encoded with security information.
This encoding provides a way for Cisco to identify and validate that the SFP
module meets the requirements for the switch.
Table 4-5 Fiber-Optic SFP Module Port Cabling Specifications
SFP Module
Wavelength
(nanometers) Fiber Type
Core Size
(micron)
Modal
Bandwidth
(MHz/km) Cable Distance
1000BASE-SX 850 MMF 62.5
62.5
50.0
50.0
160
200
400
500
722 ft (220 m)
902 ft (275 m)
1640 ft (500 m)
1804 ft (550 m)
1000BASE-LX/LH 1300 MMF
1
SMF
1. A mode-conditioning patch cord is required. Using an ordinary patch cord with MMF, 1000BASE-LX/LH SFP modules, and
a short link distance can cause transceiver saturation, resulting in an elevated bit error rate (BER). When using the LX/LH
SFP module with 62.5-micron diameter MMF, you must also install a mode-conditioning patch cord between the SFP module
and the MMF cable on both the sending and receiving ends of the link. The mode-conditioning patch cord is required for link
distances greater than 984 feet (300 m).
62.5
50.0
50.0
9/10
500
400
500
—
1804 ft (550 m)
1804 ft (550 m)
1804 ft (550 m)
6.2 mi (10 km)
1000BASE-ZX 1550 SMF 9/10 — 43.4 to 62 mi (70 to
100 km)
2
2. 1000BASE-ZX SFP modules can reach up to 100 km by using dispersion-shifted SMF or low-attenuation SMF; the distance
depends on the fiber quality, the number of splices, and the connectors.