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Catalyst2940 Switch Hardware Installation Guide
OL-6157-01
Chapter1 Overview Front-Panel Description
SFP Modules
The Catalyst 2940-8TF-S switch uses a field-replaceable SFP module to establish Gigabit connections.
You insert an SFP module into the SFP module slot on the front of the switch.
The Cisco SFP modules that are supported by the Catalyst 2940-8TF-S switch include:
•1000BASE-LX, fiber-optic
•1000BASE-SX, fiber-optic
•1000BASE-T, copper
•Coarse Wavelength-Division Multiplexing (CDWM), fiber-optic
Note The Catalyst 2940-8TF-S switch only supports 1000 Mbps and full-duplex modes on SFP modules.
The 1000BASE-LX and 1000BASE-SX SFP modules are used to establish fiber-optic connections. You
use fiber-optic cables with LC connectors to connect to an SFP module. The SFP modules support 850
to 1550 nm nominal wavelengths. These field-replaceable modules provide the uplink optical interfaces,
laser send (TX), and laser receive (RX).
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 stipulated cable length for reliable communications. Table 1 -3
lists these stipulations.
The 1000BASE-T SFP module is used to establish a Gigabit Ethernet connection through a Category 5
(copper) cable. This module can provide a Gigabit Ethernet connection of up to 100 meters through a
Category 5 cable.
Use only Cisco SFP modules on the Catalyst 2940-8TF-S 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.
Table1-3 Cabling Stipulations for Fiber-Optic SFP Modules
SFP
Module
62.5/125micron
Multimode
850nm1 Fiber
1. nm = nanometer
50/125micr on
Multimode
850nm Fiber
62.5/125micron
Multimode
1310nm Fiber
50/125micron
Multimode
1310nm Fiber
9/125micron
Single-mode
1310nm Fiber
8micron
Single-mode
Dispersion
Shifted Fiber
SX 275 m2 at
200 Mhz-km
2. m = meter
550 m at
500 Mhz-km —
LX — — 550 m at
500 Mhz-km 550 m at
400 Mhz-km 10 km —
CWDM3
3. CWDM = Coarse Wavelength-Division Multiplexing
1470, 1490, 1510,
1530, 1550, 1570,
1590, 1610
SMF 9/125 — 62 miles (100
km) 1470, 1490,
1510, 1530,
1550, 1570,
1590, 1610