Cisco Catalyst 2900 XL Series Installation And Configuration Manual page 22

Physical Description
SC Connector Description and Fiber-Optic Cabling Requirements
The ATM 155 SM-MR and SM-LR Fiber modules require an SC connector and fiber-optic
cable as shown in Figure 1-6. The maximum distance for single-mode fiber-optic network
connections is 15 kilometers for medium reach and 40 kilometers for long reach.
Figure 1-6
Rx
The module transmits data through the transmit (Tx) fiber-optic port and receives data from
the receive (Rx) fiber-optic port. The fiber-optic port transmits on a 1300-nanometer
wavelength.
1-10
Catalyst 2900 Series XL ATM Modules Installation and Configuration Guide
SC Connector and Fiber-Optic Cable
Tx