Asynchronous Terminal Connections; Interference Considerations - Cisco ASR 903 Installation Instructions Manual

Site Cabling Guidelines
Also consider any additional interface equipment you need, such as transceivers, hubs, switches, modems,
channel service units (CSU), or data service units (DSU).
Before you begin, read these important notes about cabling:
• The T1/E1 interface module for the Cisco ASR 903 Router uses a high-density connector that requires
the use of a T1/E1 interface cable and a customer-provided patch panel. For more information, see the
Cisco ASR 903 Router Hardware Installation Guide . Note that the Cisco ASR 903 Router as a satellite
shelf does not use the T1/E1 interface module. The Cisco ASR 903 Router as a satellite shelf supports
only ethernet ports.
• Shielded cables must be used to connect to the DB-25 alarm connector on the fan tray in order to comply
with FCC/EN55022/CISPR22 Class A emissions requirements. For information about the fan tray alarm
port, see the Cisco ASR 903 Router Hardware Installation Guide.
Before you install the Cisco ASR 903 Router as a satellite shelf, have all the additional external equipment
and cables on hand. For information about ordering, contact a Cisco customer service representative.
The extent of your network and the distances between the network interface connections depend in part on
the following factors:
• Signal type
• Signal speed
• Transmission medium
The distance and rate limits referenced in the following sections are the IEEE-recommended maximum speeds
and distances for signaling purposes. Use this information as a guideline in planning your network connections
>prior to installing the Cisco ASR 903 Router as a satellite shelf.
If wires exceed the recommended distances, or if wires pass between buildings, give special consideration to
the effect of a lightning strike in your vicinity. The electromagnetic pulse caused by lightning or other
high-energy phenomena can easily couple enough energy into unshielded conductors to destroy electronic
devices. If you have had problems of this sort in the past, you may want to consult experts in electrical surge
suppression and shielding.

Asynchronous Terminal Connections

The RSP provides a console port to connect a terminal or computer for local console access. The port has an
RJ-45 connector and supports RS-232 asynchronous data with distance recommendations specified in the
IEEE RS-232 standard.

Interference Considerations

When wires are run for any significant distance, there is a risk that stray signals will be induced on the wires
as interference. If interference signals are strong, they can cause data errors or damage to the equipment.
The following sections describe sources of interference and how to minimize its effects on the Cisco ASR
903 system.
Cisco ASR 9000 Series Aggregation Services Router Satellite Systems Installation Guide
14
Installing the Cisco ASR 903 Router as a Satellite Shelf