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Prepare for Installation
Electrical Circuit Requirements
Each chassis requires a dedicated electrical circuit. If you equip the device with dual-power feeds, provide a
separate circuit for each power supply to avoid compromising the power redundancy feature.
The chassis supports both DC source or an AC source. Ensure that equipment grounding is present and observe
power-strip ratings. Make sure that the total ampere rating of all the products plugged into the power strip
does not exceed 80% of the rating.
Site Cabling Guidelines
This section contains guidelines for wiring and cabling at your site. When preparing your site for network
connections to the chassis, consider the type of cable that is required for each component and cable limitations.
Consider the distance limitations for signaling, electromagnetic interference (EMI), and connector compatibility.
Possible cable types are fiber, thick or thin coaxial, foil twisted-pair, or unshielded twisted-pair cabling.
Also, consider any additional interface equipment that you need, such as transceivers, hubs, switches, modems,
channel service units (CSU), or data service units (DSU).
Before you install the chassis, have on hand all additional external equipment and cables. 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 that are referenced in the following sections are the IEEE-recommended maximum
speeds and distances for signaling purposes. Use this information as a guideline when planning your network
connections before installing the chassis.
If wires exceed the recommended distances, or if wires pass between buildings, give special consideration to
the possibility of a lightning strike in your vicinity. The electromagnetic pulse due to 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 chassis 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 that are specified
in the IEEE RS-232 standard.
Interference Considerations
When wires are run for any significant distance, there is a risk of receiving stray signals on the wires as
interference. If interference signals are strong, it results in data errors or equipment damage.
The following sections describe the sources of interference and how to minimize their effects on the chassis.
Cisco ASR-920-20SZ-M Aggregation Services Router Hardware Installation Guide
Electrical Circuit Requirements
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