
Chapter 2 Preparing the Cisco uBR7225VXR Router for Installation
Provisioning the Cable Headend
Headend Wiring
This section provides guidelines for setting up the headend wiring and cabling at your site. When planning the location of the new system, consider the distance limitations for signaling, EMI, and connector compatibility, as described in the following sections.
Interference Considerations
When wires are run for any significant distance in an electromagnetic field, interference can occur between the field and the signals on the wires. This fact has two implications for the construction of headend wiring:
•Bad wiring practice can result in radio interference emanating from the wiring, ingress noise,
•Strong EMI, especially when caused by lightning or radio transmitters, can destroy the signal drivers and receivers in the Cisco uBR7225VXR router, and can even create an electrical hazard by conducting power surges through lines and into equipment. (Review the safety warnings in the “Safety with Electricity” section on page
If you use
If wires exceed 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
Distance Limitations and Interface Specifications
The size of your networks and the distances between connections depend on the type of signal, the signal speed, and the transmission media (the type of cabling used to transmit the signals). For example, standard coaxial cable has a greater channel capacity than
Note We recommend that you do not exceed specified transmission rate and distance limits.
When preparing your site for network connections to the Cisco uBR7225VXR router, you must consider a number of factors related to each type of interface:
•The type of cabling required for each type of interface (fiber, thick or thin coaxial, shielded
•Distance limitations for each signal type
•The specific cables you need to connect each interface
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