Quick Start Guide -- Cabling the Cisco uBR 3x10 RF Switch to the Cisco uBR10012 CMTS

Warning Only trained and qualified personnel should be allowed to install, replace, or service this product. Statement 1030.

1 Overview

This quick start guide describes the equipment and steps used to connect coaxial cables between the Cisco 3x10 RF Switch and the working and protect cable interface line cards (Cisco uBR-MC28C, and Cisco uBR-MC16C, E, or S) in a Cisco uBR10012 Cable Modem Termination System (CMTS).

A single Cisco uBR10012 CMTS supports up to eight Cisco cable interface line cards. Each line card has one or two downstream and six or eight upstream cable interfaces for a total of up to 16 downstream and 64 upstream interfaces in a fully populated chassis.

2 Protection Scheme

The N+1 redundancy protection scheme you select for your system depends on the number of cable interface line cards you have installed in the Cisco uBR10012 CMTS. The 7+1 eight-card redundancy scheme supports redundancy for the cable interface line cards installed in a fully populated Cisco uBR10012 chassis.

One Cisco 3x10 RF Switch is used in this configuration, allowing you to deploy a redundancy scheme where one protecting cable interface line card supports from one to seven working cable interface line cards in the same chassis.

3 RF Cable Assemblies

The following sections describe the coaxial cable, F-connector assemblies, and header blocks required to support N+1 redundancy using the Cisco uBR 3x10 RF Switch, Cisco CMTSs, and the Vecima HD4040 series IF-to-RF upconverter.

Although you may construct and implement your own cabling system according to the specifications outlined here, we recommend using the Cisco N+1 cabling solution designed specifically for this CMTS feature and the Cisco pre-assembled, terminated cables and cable bundles.

Coaxial Cables

The coaxial cable approved for use in the Cisco N+1 cable assembly is Belden YR46940. The cable bundle features 10 individual segments of Belden YR46940-type coaxial cable enclosed in an external sheath. Each segment of coaxial cable is a different color. The single gray and brown RF cables are pre-terminated with F-connectors to accommodate downstream IF signals from the Cisco CMTS to the Vecima HD4040 series IF-to-RF upconverter input. (See Figure 1.)

Connectors

The MCX connectors that terminate in the header block at the Cisco RF Switch are a special 75-ohm MCX connector available from White Sands Engineering.

The F-connectors that terminate at the upconverter are Whitesands ASFP connectors (or alternate). The output cabling kit includes 13 F-connectors to use for modification or repair.

Header Blocks

The header block holds the MCX connectors that terminate the coaxial cables. These are Cisco MCX header blocks that mate to the Cisco 3x10 RF Switch. (See Figure 1.)

The header blocks are slightly beveled at the top and have offset alignment pins to prevent accidentally installing the header block upside down.

An extraction tool is shipped with the Cisco 3X10 RF Switch to remove MCX connectors from the header blocks, if necessary.

Note Custom cables or cable components such as header blocks, crimping tools, or connectors are available from custom cable fabricators such as White Sands Engineering (1-800-JUMPERS).

For more information on Vecima HD4040 series IF-to-RF upconverters, go to the following URL:

http://www.vecimanetworks.com/

4 Connecting RF Cables to the Cisco uBR 3x10 RF Switch

RF cables are connected to the CMTS, PROTECT and CABLE PLANT portions of the Cisco uBR 3x10 RF Switch using header blocks.

•

CMTS-One of eight RF connection groups—These groups of RF cables connect to cable interface line cards designated as the working line cards and to IF-to-RF upconverters.

•

PROTECT-One of the two RF connection groups—These groups of RF cables connect to cable interface line cards designated as the protect line cards.

•

CABLE PLANT-One of the eight RF connection groups—These groups of RF cables connect to the coaxial or fiber-optic transceivers at the cable headend or hub.

Figure 2 displays a detailed view of a header block that connects to a Cisco uBR 3x10 RF Switch.

Attaching the Header Blocks

Step 1

With the beveled edge of the header block at the top, align the pins on the header block with the two holes in the appropriate section of the RF switch.

Step 2

Press the header block into place, using equal pressure on both the upper and lower portions of the header block.

Step 3

Use a flat-blade screwdriver to tighten both captive installation screws (top and bottom of the header block) to prevent accidental disconnections.

Mapping the RF Cables

Use the following guidelines to map cables between the Cisco uBR 3x10 RF Switch and the CMTS:

•

The header block ports labeled A through E and H through L connect to the upstream interfaces on the line card.

•

The header block ports labeled F, G, and M are for the downstream connections. Therefore, Cisco uBR-MC28C line card ports, DS0 and DS1, can be attached to any two of the three available downstream ports.

This mapping scenario is applicable for both working and protect cable interface line cards when employing N+1 redundancy.

The distinction between which cable interface line card serves as the protect line card and which line cards serve as the working line cards is decided by which cable group (line card) is plugged into the CMTS or the PROTECT group on the RF switch, and by the configuration you specify using the information in the "N+1 Redundancy for the Cisco CMTS" chapter of the Cisco Cable Modem Termination System Feature Guide.

Connecting the RF Cables to the Header Blocks

Step 1

Push the MCX connectors into the holes in the header blocks as they have been mapped. See Figure 2.

Step 2

Gently wiggle each connector to make sure that the connection is secure.

Connecting to the Line Cards

Step 1

After installing the cable management bracket (optional), Run the cables from the RF switch down to the line cards.

Step 2

Connect the individual RF connectors to the cable interfaces on the cable interface line card.

Step 3

Tighten the F-connectors to a value between 10 (recommended) and 15(maximum) inch-pounds (1.1298 and 1.7339 Nm).

Output Cabling

Output cable headers are wired in the reverse sequence of the input headers (see Figure 3). A cabling kit (Cisco part number CAB-RFSW-3X10-10T) is available from Cisco. See the Cable Plant wiring section of Figure 3.

5 Part Numbers


Description	Part Number
Cisco (10-cable bundle)	CAB-RFSW-3X10-10T
Cisco (single cable)	CAB-RFSW-3X10-T
White Sands Engineering, Inc.
Belden¹ (cable bundle)	YR46941
Belden (single cable)	YR46940
Header block	MCXHEADERBK
Extractor tool	REMTOOL
MCX connector	MCXFP
"F" connector	ASFP
MCX, "F" crimp tool	ACT-483
MCX connector strip tool: Dual-shielded cables	PN-CPT-7538-125
Dual-shielded F connector strip tool	CPT-7538

¹75-ohm precision miniature video cable

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