Table Of Contents
Cabling Cisco uBR 3x10 RF Switches to Cisco uBR-MC3GX60V
Cable Interface Line Cards in a Cisco uBR10012 CMTS Router Quick Start Guide
Published: October 15, 2010, OL-23736-01
This document describes the procedures used to connect the cables between the Cisco uBR 3x10 RF Switches and the working and protect Cisco uBR-MC3GX60V cable interface line cards installed in a Cisco uBR10012 Cable Modem Termination System (CMTS).
The N+1 redundancy protection scheme you select for your system depends largely upon the number of cable interface line cards installed in the Cisco uBR10012 chassis. The N+1 redundancy scheme supports redundancy for the cable interface line cards installed in a fully populated Cisco uBR10012 chassis. Other redundancy schemes can be used to support partial cable interface line cards in a Cisco uBR10012 chassis.
A single Cisco uBR10012 CMTS supports up to eight Cisco uBR-MC3GX60V cable interface line cards. Each of these cards feature 6 downstream and 20 upstream cable interfaces for a total of 72 downstream and 60 upstream interfaces in the chassis. Two Cisco uBR 3x10 RF Switches are used to connect to the Cisco uBR10012 CMTS to deploy a redundancy scheme in which one protect cable interface line card supports one to seven working cable interface line cards in the same chassis.
RF Cable Assembly Specifications
The following sections describe the coaxial cable and header block assemblies required to support N+1 redundancy between the Cisco uBR 3x10 RF Switches and the Cisco CMTS.
Note Although you may construct and implement your own cabling system according to the specifications outlined here, we recommend using the Cisco N+1 redundancy cabling solution designed specifically for this Cisco CMTS feature. The preassembled cable sets (Cisco part numbers CABRFSW3G60QTIMM2 and CABRFSW3G60QTPMF2) are designed to fit the rack configuration described in the Rack-Mounting the Cisco uBR 3x10 RF Switch with the Cisco uBR10012 CMTS - Quick Start Guide. Other rack configurations require custom cables.
Note Quad-shield coaxial cable bundles for the Cisco uBR-MC3GX60V cable interface line card can be purchased from Cisco with the Universal Cable Holders (UCH) already connected to the coaxial cable bundles. Alternatively, custom-length quad-shield coaxial cable bundles can be purchased from third-party vendors, with the UCH either connected to the cable bundles or provided as separate components.
Note Prepopulated custom cables for this reference design, 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).
Figure 1 shows the cable bundle for the Cisco uBR-MC3GX60V cable interface line card to the RF Switch that has two UCH2 units attached to one end and two RF Switch header blocks attached to the other end. This cable is 3.2 feet (1 m) long and the part number is CABRFSW3G60QTIMM2.
Note When using the CABRFSW3G60QTIMM2 cable kit, you should mount the RF Switches directly above the Cisco uBR10012 router in the rack for the cables to reach between the line card and the RF Switch.
Figure 1 Cable Bundle with UCH2 Units and RF Switch Header Blocks
Figure 2 shows the cable bundle for the RF Switch to the HFC plant that has 2 RF Switch header blocks attached to one end and 20 F connectors attached to the other end. This cable is 9.84 feet (3 m) long and the part number is CABRFSW3G60QTPMF2.
Figure 2 Cable Bundle with RF Switch Header Blocks and F Connectors
Note Customers purchasing custom-length quad-shield coaxial cable bundles from third-party vendors can purchase spare UCH and spare RF Switch header blocks from Cisco.
Universal Cable Holders
Universal cable holders (UCH) are used to attach the cables to the Cisco uBR-MC3GX60V cable interface line cards. For information about installing cables in the UCH, see Installing Cisco uBR-MC3GX60V Cable Interface Line Cards - Quick Start Guide.
Caution Always use universal cable holders to avoid damage to the connectors on the line cards.
Coaxial Cable Bundles
The coaxial cable bundles have five coaxial cables enclosed in an external sheath. Each cable in the bundle has a different color. See Figure 3.
Figure 3 Cable Bundles with Cable Holders and Header Blocks
Cisco cables are color-coded for easy reference and installation. The cable color corresponds to a specific port on the card.
Table 1 provides a list of the cable ports and associated cable color applicable when using MC3GX60 dual-shielded or quad-shielded cables. Figure 6 provides header block and cable designations as viewed from the cable side of the header blocks.
Note The Cisco uBR-MC3GX60V cable interface line card must use quad-shielded cables only in Europe. In all other regions, this line card can use dual-shielded or quad-shielded cables.
Note Precision miniature video coaxial cables are available in various colors, and you can use any cable color combination. However, when you are connecting the Cisco uBR-MC3GX60V cable interface card to the Cisco RF Switch, we recommend that you install the cables in the UCH as listed in Table 1.
Header blocks hold the MCX connectors that attach to the individual coaxial cables that mate with the Cisco uBR 3x10 RF Switch. Ensure that the header block is in the correct orientation before inserting the cables.
Note The header blocks used here are slightly beveled at the top for easy identification. In addition, the alignment pins on the header blocks are offset, preventing you from accidentally connecting the header block upside down.
Figure 4 displays a detailed view of a header block that connects to the RF Switches.
Figure 4 Cisco uBR 3x10 RF Switch Header Block
Note An extraction tool is shipped with the Cisco uBR 3x10 RF Switch to remove MCX connectors from the header blocks and universal cable holders, if necessary.
Connecting RF Cables to the Cisco uBR 3x10 RF Switch
The following instructions describe the connection process for the customized RF cables and the maintenance of the Cisco preconfigured cable bundles.
The RF cables are connected to the CMTS, PROTECT, and CABLE PLANT portions of the Cisco uBR 3x10 RF Switch in bundles of RF cables. The cables are terminated with MCX connectors that attach to the header blocks connected to the RF Switch at one of the following locations:
•CMTS—These groups of RF cables connect to the cable interface line cards designated as the working line cards.
•PROTECT—These groups of RF cables connect to the cable interface line cards designated as the protect line cards.
•CABLE PLANT—These groups of RF cables connect to the splitters and diplexers at the cable headend or hub.
The cables are terminated with MCX connectors that attach to the header blocks connected to the RF Switches (see Figure 5):
Figure 5 Cabled Header Block and RF Switch
To insert the cables in the header block and connect the header block to the Cisco uBR 3x10 RF Switch:
Step 1 Insert the MCX connectors into the header blocks according to the mapping in the "CMTS and PROTECT Cabling" section.
Step 2 Gently pull on the cables to ensure that they are firmly seated in the header blocks.
Step 3 With the beveled edge of the header block at the top, line up the two alignment pins on the header block with the two holes corresponding to the RF connector group (CMTS, PROTECT, or CABLE PLANT) section of the RF Switch.
Step 4 Press the header block into place, using equal pressure on both the upper and lower portions of the header block.
Caution To ensure proper installation and avoid poor connections, ensure that the cables are not positioned at too acute an angle.
Step 5 Use a flat-blade screwdriver to tighten the captive installation screws at both the top and bottom of the header block to prevent accidental disconnections.
Caution Do not overtighten. We recommend that you tighten the screws to 5 to 7 inch-pounds.
Tip Alternately, mount the header blocks on the Cisco uBR 3x10 RF Switch first, then insert the MCX connectors. Do not fully tighten the header blocks to the RF Switch before gently pulling on the cables to ensure that they are firmly seated.
CMTS and PROTECT Cabling
This section describes the mapping of RF cables from the working and protect line cards to the Cisco uBR 3x10 RF Switch. Figure 6 provides header block and cable designations as viewed from the cable side of the header blocks.
When you connect RF cables between the RF Switch and a cable interface line card installed in a Cisco uBR10012 chassis, ensure that all the RF cables in the bundle attach to interfaces on the same cable interface line card installed in the Cisco uBR10012 chassis. (Refer to Figure 5, Table 2, Table 3, Table 4, and Table 5 for line card to RF Switch port mapping information.)
Use the following guidelines to map cables between the Cisco uBR 3x10 RF Switch and the Cisco uBR10012 CMTS:
•All the cable interface ports labeled A through E and H through L on the header block must attach to the upstream interfaces on the Cisco uBR10012 chassis.
•The cable interface ports labeled F, G, M, and N on the header block do not attach to anything in the Cisco RF Switch. Therefore, it should not be connected to any cable interface on the Cisco uBR10012 CMTS.
Note The line card to RF Switch port mapping is applicable to both working and protect cable interface line cards when employing N+1 redundancy. The distinction between which cable interface line card serves as a protect line card and which serves as a working line card is determined by whether the header block is plugged into the working (switch side) or protect group of slots on the Cisco uBR 3x10 RF Switch and by the configuration you specify. For more details, see the "N+1 Redundancy for the Cisco CMTS" chapter of the Cisco IOS CMTS Cable Software Configuration Guide.
Tip (Optional) Install the cable management bracket, before cabling the RF Switch.
Figure 6 Wiring the CMTS and Protect Headers (Cable Plant Headers Shown for Comparison)
Cable Plant Cabling
CABLE PLANT header blocks are wired in the reverse sequence of the CMTS and Protect header blocks (see Figure 7). Use the same connection methods as described in the "Connecting RF Cables to the Cisco uBR 3x10 RF Switch" section.
Note CABLE PLANT slots on the Cisco uBR 3x10 RF Switch are numbered in reverse sequence from CMTS and PROTECT. Slot number one is on the right. Figure 7 provides header block and cable designations as viewed from the cable side of the header blocks.
Figure 7 Wiring the Cable Plant Cable Headers (CMTS/Protect Headers Shown for Comparison)
For safety information, refer to:
For additional hardware installation and software configuration information, go to:
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