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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
OL-2239-05
Chapter1 Overview of Cisco uBR7200 Series Software
cops tcp window-size
Downstream Load Balancing Distribution with Upstream Load Balancing
Cisco IOS Release 12.3(17b)BC4 introduces further enhancements to downstream load balancing, resulting
in equalized upstream load balancing group members. This enhancement synchronizes the pending statistic
between different cable interface line cards in the load balancing group.
This enhancement performs downstream load balancing that accounts for loads on upstream channels in the
same upstream load balancing group, rather than on the basis of the entire downstream channel load. Prior
Cisco IOS releases may not have distributed cable modems evenly over individual upstream channels, nor in
a way that accounted for downstream and upstream segment loads that account for one another.
This enhancement applies when downstream load balancing occurs on a headend system with separate
upstream load balancing segments; the upstream segments are spread over multiple downstreams segments.
This enhancement provides an alternative downstream load balancing scheme that accounts and makes use
of per-upstream loads rather than total downstream loads.
For additional information about Load Balancing on the Cisco CMTS, refer to the following documents on
Cisco.com:
• Load Balancing and Dynamic Channel Change on the Cisco CMTS
http://www.cisco.com/en/US/products/hw/cable/ps2217/products_feature_guide09186a00801b17f
2html
• Cisco Broadband Cable Command Reference Guide
http://www.cisco.com/en/US/products/hw/cable/ps2217/products_command_reference_book0918
6a0080108e88.html
Dynamic Channel Change (DCC) for Loadbalancing
Cisco IOS Release 12.3(17a)BC introduces Dynamic Channel Change (DCC) and DCC for Load
Balancing on the Cisco CMTS.
DCC in DOCSIS 1.1 dynamically changes cable modem upstream or downstream channels without
forcing a cable modem to go offline, and without re-registration after the change. DCC supports four
different initializations, instead of one, as in earlier DOCSIS support.
DCC and DCC for load balancing is supported on the Cisco uBR7246VXR router and the
CiscouBR10012 router with distributed cable interface line cards, including the CiscoMC28U and the
CiscoMC5X20S/U/H.
• Load Balancing techniques allow for moving cable modems with DCC by using configurable
initialization techniques.
• DCC allows line card channel changes across separate downstream channels in the same cable
interface line card, with the DCC initialization techniques ranging from 0 to 4.
• DCC transfers cable modem state information from the originating downstream channel to the target
downstream channel, and maintains synchronization of the cable modem information between the
cable interface line card and the Network Processing Engine (NPE) or Route Processor (RP).
• When the target channel is in ATDMA mode, only DOCSIS 2.0-capable modems can be
successfully load balanced. (Only DOCSIS 2.0-capable modems can operate on an ATDMA-only
upstream channel.) Cisco recommends identical channel configurations in a load balancing group.