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Cisco Broadband Cable Command Reference Guide
OL-1581-08
Chapter 2 Cisco CMTS Configuration Commands
cable load-balance group (global configuration)
Command History
Usage Guidelines The cable load-balance command creates a load-balance group, which can then be assigned to a number
of upstream and downstream cable interfaces to allow the Cisco CMTS to load balance cable modems
as needed. The Cisco CMTS can use the load-balance groups for static, passive, and dynamic load
balancing of both upstream and downstream channels. You can configure downstreams and upstreams
to use the same load balancing parameters, or you can configure upstreams and downstreams separately.
Note
You can create a maximum of 20 load-balance groups on each chassis. However, you can reuse those
load-balance groups on different sets of cable interfaces, as long as they are in different domains. If
downstreams are not included in a load-balance group, then each downstream can be considered a
separate domain.
Use the cable load-balance group (global configuration) command to initially create and configure a
load-balance group. Then use the cable load-balance group (interface configuration) command to
assign this load-balance group to an upstream or downstream, so that the cable interface will begin
participating in load-balancing operations.
You can configure a load-balance group to use one of the following types of load-balancing methods:
•
Modem Method —Uses the number of active cable modems on an interface.
•
Service Flow Method —Uses the number of active Service Flow IDs (SFIDs) on an interface.
•
Utilization Method —Uses an interface’s current percentage of utilization.
See the following sections for more information about each method.
Modem Method
The modem method of load-balancing uses the number of active cable modems on an interface to
determine the current load. This is a form of distribution-based load balancing, in which the absolute
numbers of modems are used to determine whether interfaces are load balanced.
This method does not take into account the amount of traffic flowing through the cable modems, but the
system does take into account the relative bandwidth of the channels being used, so that channels with
higher bandwidths are allocated higher numbers of cable modems. This means that when interfaces are
using different channel widths or modulation profiles, the system can assign different numbers of cable
modems to the interfaces to achieve a balanced load. For example:
•
Channel widths— If two upstreams are being load balanced, and one upstream is configured with a
channel width of 1.6 MHz and the other upstream is configured for a channel width of 3.2 MHz, the
Cisco CMTS allocates twice as many cable modems to the second upstream, because its channel
width is twice as large as the first upstream’s channel width.
• Modulation profiles— If one downstream is configured for 64-QAM and the other downstream is
configured for 256-QAM, the Cisco CMTS allocates a proportionately larger number of cable
modems to the second downstream so as to achieve a balanced load.
When both the channel width and different modulation profile are set differently on two interfaces, the
system calculates a “weight” value to use as a guide to determine the relative bandwidths of the
interfaces.
Release Modification
12.2(15)BC1 This command was introduced for the Cisco uBR7246VXR and
Cisco uBR10012 routers.