- Cable Modem Upstream RF Adaptation
- Configuring Downstream Cable Interface Features on the Cisco CMTS Routers
- Configuring Upstream Cable Interface Features on the Cisco CMTS Routers
- Cable Modem Steering on the Cisco CMTS Routers
- DOCSIS 2.0 A-TDMA Modulation Profiles for the Cisco CMTS Routers
- DOCSIS 3.0 Downstream Bonding for Bronze Certification
- Downstream Channel ID Assignment on the Cisco CMTS Routers
- Downstream Resiliency Bonding Group
- IGMP-Triggered Dynamic Channel Change Load Balancing for DOCSIS 2.0 Cable Modems
- IGMP-Triggered VDOC Broadcast Support on the Cisco CMTS Routers
- Load Balancing, Dynamic Channel Change, and Dynamic Bonding Change on the Cisco CMTS Routers
- M-CMTS DEPI Control Plane
- Restricted/General Load Balancing and Narrowband Dynamic Bandwidth Sharing with Downstream Dynamic Load Balancing
- RSVP-Based Video on Demand Support Over DOCSIS
- S-CDMA and Logical Channel Support on the Cisco CMTS Routers
- Spectrum Management and Advanced Spectrum Management for the Cisco CMTS
- Support for Extended Upstream Frequency Ranges
- Upstream Bonding Support for D-PON on the Cisco CMTS Routers
- Upstream Channel Bonding
- Upstream Scheduler Mode for the Cisco CMTS Routers
- Upstream Utilization Optimization on the Cisco CMTS Routers
- Wideband Modem Resiliency
- Downgrading Channel Bonding in Battery Backup Mode
- Index
- Prerequisites for Cable Modem Upstream RF Adaptation
- Restrictions for Cable Modem Upstream RF Adaptation
- Information About Cable Modem Upstream RF Adaptation
- How to Configure Cable Modem Upstream RF Adaptation
- Troubleshooting Tips
- Verifying Cable Modem Upstream RF Adaptation
- Configuration Examples for Cable Modem Upstream RF Adaptation
- Additional References
- Feature Information for Cable Modem Upstream RF Adaptation
Cable Modem Upstream RF Adaptation
First Published: June 13, 2011
The Cable Modem Upstream RF Adaptation feature uses per cable modem physical layer statistics to identify and automatically move cable modems to another logical upstream channel within the same physical port. This is to prevent unnecessary channel-wide parameter changes, which reduces throughput, disrupts traffic flow for all modems, and makes some modems to go offline in extreme cases.
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://tools.cisco.com/ITDIT/CFN/. An account on http://www.cisco.com/ is not required.
Contents
- Prerequisites for Cable Modem Upstream RF Adaptation
- Restrictions for Cable Modem Upstream RF Adaptation
- Information About Cable Modem Upstream RF Adaptation
- How to Configure Cable Modem Upstream RF Adaptation
- Troubleshooting Tips
- Verifying Cable Modem Upstream RF Adaptation
- Configuration Examples for Cable Modem Upstream RF Adaptation
- Additional References
- Feature Information for Cable Modem Upstream RF Adaptation
Prerequisites for Cable Modem Upstream RF Adaptation
- Multiple logical channels must be configured.
- Logical channels should be enabled per upstream.
- Logical channel 0 is the preferred primary logical channel, and logical channel 1 is the preferred secondary logical channel. This increases interoperability with other CMTS applications such as load balancing and upstream channel bonding.
The table below shows the hardware compatibility prerequisites for this feature.
![]() Note | The hardware components introduced in a given Cisco IOS Release are supported in all subsequent releases unless otherwise specified. |
Platform |
Processor Engine |
Cable Interface Cards |
---|---|---|
Cisco uBR10012 Universal Broadband Router |
Cisco IOS Release 12.2(33)SCF and later releases Cisco IOS Release 12.2(33)SCH and later releases
|
Cisco IOS Release 12.2(33)SCF and later releases |
Cisco uBR7246VXR Universal Broadband Router |
Cisco IOS Release 12.2(33)SCF and later releases
|
Cisco IOS Release 12.2(33)SCF and later releases
|
Cisco uBR7225VXR Universal Broadband Router |
Cisco IOS Release 12.2(33)SCF and later releases
|
Cisco IOS Release 12.2(33)SCF and later releases
|
Restrictions for Cable Modem Upstream RF Adaptation
- Logical channel 1 cannot be part of an upstream bonding group.
- The Upstream Channel Bonding (USCB) feature coexists with the Cable Modem Upstream RF Adaptation feature; however, cable modems in the multiple transmits channel (MTC) mode are excluded.
- Cable modems that use the multiple receive channel (MRC) mode without MTC may participate in cable modem upstream RF adaptation because these cable modems can be moved using the dynamic channel change (DCC) method.
- Advanced spectrum management is not supported in multiple logical channel configurations.
- Dynamic channel-width configurations are not supported.
- A pair of logical upstream channels configured with a mix of DOCSIS modes (i.e. SCDMA on logical channel 0 and ATDMA on logical channel 1) is supported, however, the CMTS will request that the cable modem uses the initialization technique 1 for the DCC.
Information About Cable Modem Upstream RF Adaptation
The Cable Modem Upstream RF Adaptation feature moves a single cable modem or a group of cable modems to a more robust channel when a user-defined set of per cable modem PHY statistics does not meet a set of user-specified thresholds. Similarly, it releases a single cable modem or a group of cable modems from the secondary channel when the user-defined set of per cable modem PHY statistics exceeds a set of user-specified thresholds.
The following relocation methods are used while moving a cable modem to and from the secondary logical upstream channel:
- UCC for DOCSIS 1.0 cable modems.
- DCC initialization technique 2 for DOCSIS 1.1 and newer cable modems. Initialization technique 2 performs periodic ranging. The cable modem is kept online and allowed to start on the new channel with periodic ranging.
- DCC initialization technique 1 for any configuration where at least one logical channel uses the SCDMA DOCSIS mode. The initialization technique 1 broadcasts the initial ranging. The cable modem is kept online and re-registration is avoided, but this technique requires completion of initial ranging.
The following PHY statistics are used while moving a cable modem to and from the secondary logical upstream channel:
- Ranging burst Modulation Error Ratio (MER)
- Data burst MER for JIB3-based line cards
- Correctable and uncorrectable Forward Error Correction (FEC)
The cable modems to be relocated from the primary logical upstream channel to the secondary channel are marked as downgrade candidates. Similarly, the cable modems to be relocated from the secondary logical upstream channel to the primary channel are marked as upgrade candidates. Tracking individual cable modem statistics prevents a cable modem or a small group of cable modems from lowering the available bandwidth for the larger population of cable modems.
Following are the step-by-step timer-based events that occur during RF adaptation:
- General timer event—The PHY statistics of the cable modems on the RF adapt-enabled channel are checked. The cable modems that fail or exceed the set threshold are flagged as either downgrade or upgrade candidates.
- Candidate timer event—The PHY statistics of the cable modems that are flagged as downgrade or upgrade candidates are checked again to verify if the impairment still exists.
- Relocation timer event—The cable modems that continue to fail or exceed the threshold are relocated.
After a line card switchover, the cable modems remain online on either the primary or secondary logical upstream channel depending on the state of the cable modem prior to the switchover. The upgrade and downgrade candidate cable modems, and the cable modem movement history from primary to secondary logical upstream channel and vice versa are not retained after a line card switchover. The Cable Modem Upstream RF Adaptation feature is not affected by a PRE switchover and the candidate information and history is retained during a PRE switchover.
The Cable Modem Upstream RF Adaptation feature is disabled by default. For information about how to enable this feature, see How to Configure Cable Modem Upstream RF Adaptation.
Related CMTS Software Features
The Cable Modem Upstream RF Adaptation feature via spectrum management integrates with and leverages from the following CMTS software features:
Multiple Logical Channels
The ability to use a multiple logical channel configuration to relocate cable modems with PHY impairments is a key capability of the Cable Modem Upstream RF Adaptation feature. In a cable modem upstream RF adaptation configuration, the logical channels are used as:
- Logical Channel 0—This is the default primary logical channel that cable modems registers on. The primary logical channel should be configured with performance options such as 64 QAM modulation profile irrespective of the index value.
- Logical Channel 1—This is the default secondary logical channel. The secondary logical channel should be configured with robust options, such as QPSK-based modulation profile irrespective of the index value.
You can configure the primary and secondary logical channel. When multiple logical channels are configured, the upstream-related commands are categorized into physical port level and logical channel level groups. Logical channel level commands use the format of cable upstream port logical-channel-index, where port denotes the physical port number, and logical-channel-index denotes the logical channel index number.
The following logical channel-level configuration options have an impact on the Cable Modem Upstream RF Adaptation feature:
- DOCSIS mode. In the case of SCDMA, change in parameters like codes-per-minislot may also impact robustness.
- Modulation profile.
- Equalization-coefficient (that is pre-equalization).
For more details on the Multiple Logical Channel feature, see S-CDMA and Logical Channel Support on the Cisco CMTS Routers .
CMTS PHY Measurement
The CMTS PHY measurements collected on a per cable modem basis is used during RF adaptation. For a cable modem upstream RF adaptation, the MER (also referred to as Signal-to-noise Ratio [SNR]), and FEC (both correctable and uncorrectable) measurements provide an accurate indication about the effect of any PHY impairments on a single cable modem.
The Cable Modem Upstream RF Adaptation feature uses the following thresholds:
- rf-adapt—Sets the RF adaptation percentage threshold.
- snr-profiles—Specifies the MER (SNR) threshold in dB.
- hysteresis—Specifies the hysteresis value.
- corr-fec—Specifies the allowable number of correctable FEC errors for the upstream.
- uncorr-fec—Specifies the allowable number of uncorrectable FEC errors for the upstream.
![]() Note | All the above thresholds are configured at the physical port level to ensure that the same collection of thresholds is used for both upgrade and downgrade. |
How to Configure Cable Modem Upstream RF Adaptation
This section describes how to configure a physical upstream and its associated logical channels for cable modem upstream RF adaptation.
Multiple logical channels must be configured.
The cable modem upstream RF adaptation is not applicable for modems that are registered in MTC mode.
If you want to customize multiple logical channels, see S-CDMA and Logical Channel Support on the Cisco CMTS Routers.
Troubleshooting Tips
Following are some scenarios that you may encounter while configuring or after configuring the Cable Modem Upstream RF Adaptation feature. Follow the recommended action to resolve these issue.
- Cable Modem Does Not Downgrade to the Secondary Logical Channel
- Cable Modem Does Not Upgrade to the Primary Logical Channel
Cable Modem Does Not Downgrade to the Secondary Logical Channel
- Possible Cause The RF adaptation downgrade threshold has been met.
- Possible Cause The RF adaptation downgrade threshold is exceeded while the cable modem is still on the downgrade candidate list.
- Possible Cause The RF adaptation downgrade threshold is exceeded after a group of cable modems are moved to the secondary logical channel.
Cable Modem Does Not Upgrade to the Primary Logical Channel
Verifying Cable Modem Upstream RF Adaptation
Command | Purpose |
---|---|
show cable rf-adapt downgrade-candidates |
To verify the downgrade candidate cable modems. |
show cable rf-adapt upgrade-candidates |
To verify the upgrade candidate cable modems. |
show cable modem rf-adapt |
To verify the RF adaptation history |
Configuration Examples for Cable Modem Upstream RF Adaptation
This section provides configuration examples for the Cable Modem Upstream RF Adaptation feature:
- Example: Configuring Cable Modem Upstream RF Adaptation on the Cisco uBR10012 Router
- Example: Configuring Cable Modem Upstream RF Adaptation on the Cisco uBR7200 Router
- Example: Non-Default Timer Configuration
Example: Configuring Cable Modem Upstream RF Adaptation on the Cisco uBR10012 Router
The following example shows how to configure the Cable Modem Upstream RF Adaptation feature on the Cisco uBR10012 router.
! interface Cable8/0/0 load-interval 30 downstream Modular-Cable 1/1/0 rf-channel 0 upstream 0-3 cable mtc-mode no cable packet-cache cable bundle 1 cable upstream max-ports 4 cable upstream bonding-group 700 upstream 0 upstream 1 upstream 2 upstream 3 attributes A0000000 cable upstream 0 connector 0 cable upstream 0 frequency 13000000 cable upstream 0 channel-width 6400000 6400000 cable upstream 0 max-logical-chans 2 cable upstream 0 threshold snr-profiles 20 0 cable upstream 0 threshold corr-fec 0 cable upstream 0 threshold uncorr-fec 0 cable upstream 0 threshold rf-adapt 0 cable upstream 0 rf-adapt cable upstream 0 0 docsis-mode scdma cable upstream 0 0 spreading-interval 16 cable upstream 0 0 codes-per-minislot 16 cable upstream 0 0 active-codes 112 cable upstream 0 0 range-backoff 3 6 cable upstream 0 0 modulation-profile 321 cable upstream 0 0 attribute-mask 20000000 no cable upstream 0 0 shutdown cable upstream 0 1 docsis-mode atdma cable upstream 0 1 minislot-size 1 cable upstream 0 1 range-backoff 3 6 cable upstream 0 1 modulation-profile 223 cable upstream 0 1 attribute-mask 20000000 no cable upstream 0 1 shutdown no cable upstream 0 shutdown cable upstream 1 connector 1 cable upstream 1 frequency 20000000 cable upstream 1 channel-width 3200000 3200000 cable upstream 1 load-balance group 80 cable upstream 1 docsis-mode scdma cable upstream 1 spreading-interval 16 cable upstream 1 codes-per-minislot 4 cable upstream 1 active-codes 112 cable upstream 1 range-backoff 3 6 cable upstream 1 modulation-profile 321 cable upstream 1 attribute-mask 20000000 no cable upstream 1 shutdown cable upstream 2 connector 2 cable upstream 2 frequency 26400000 cable upstream 2 channel-width 3200000 3200000 cable upstream 2 power-level 1 cable upstream 2 load-balance group 80 cable upstream 2 docsis-mode scdma cable upstream 2 spreading-interval 16 cable upstream 2 codes-per-minislot 4 cable upstream 2 active-codes 112 cable upstream 2 range-backoff 3 6 cable upstream 2 modulation-profile 321 cable upstream 2 attribute-mask 20000000 no cable upstream 2 shutdown cable upstream 3 connector 3 cable upstream 3 frequency 32600000 cable upstream 3 channel-width 3200000 3200000 cable upstream 3 power-level 1 cable upstream 3 load-balance group 80 cable upstream 3 docsis-mode scdma cable upstream 3 spreading-interval 16 cable upstream 3 codes-per-minislot 4 cable upstream 3 active-codes 112 cable upstream 3 range-backoff 3 6 cable upstream 3 modulation-profile 321 cable upstream 3 attribute-mask 20000000 no cable upstream 3 shutdown cable sid-cluster-group num-of-cluster 2 cable sid-cluster-switching max-request 1 ... ...
Example: Configuring Cable Modem Upstream RF Adaptation on the Cisco uBR7200 Router
The following example shows how to configure the Cable Modem Upstream RF Adaptation feature on the Cisco 7200 router.
! interface Cable1/1 load-interval 30 downstream Integrated-Cable 1/1 rf-channel 0-3 upstream 0-3 cable mtc-mode no cable packet-cache cable bundle 2 cable upstream max-ports 4 cable upstream 0 connector 4 cable upstream 0 frequency 20000000 cable upstream 0 channel-width 6400000 6400000 cable upstream 0 max-logical-chans 2 cable upstream 0 threshold snr-profiles 26 0 cable upstream 0 threshold corr-fec 5 cable upstream 0 threshold uncorr-fec 2 cable upstream 0 threshold hysteresis 4 cable upstream 0 threshold rf-adapt 0 cable upstream 0 rf-adapt cable upstream 0 0 docsis-mode atdma cable upstream 0 0 minislot-size 4 cable upstream 0 0 range-backoff 3 6 cable upstream 0 0 modulation-profile 221 cable upstream 0 0 attribute-mask 20000000 no cable upstream 0 0 shutdown cable upstream 0 1 docsis-mode atdma cable upstream 0 1 minislot-size 4 cable upstream 0 1 range-backoff 3 6 cable upstream 0 1 modulation-profile 222 cable upstream 0 1 attribute-mask 20000000 no cable upstream 0 1 shutdown no cable upstream 0 shutdown cable upstream 1 connector 5 cable upstream 1 frequency 26600000 cable upstream 1 channel-width 3200000 3200000 cable upstream 1 docsis-mode atdma cable upsteram 1 minislot-size 4 cable upstream 1 range-backoff 3 6 cable upstream 1 modulation-profile 321 cable upstream 1 attribute-mask 20000000 no cable upstream 1 shutdown cable upstream 2 connector 6 cable upstream 2 frequency 30000000 cable upstream 2 channel-width 3200000 3200000 cable upstream 2 docsis-mode atdma cable upsteram 2 minislot-size 4 cable upstream 2 range-backoff 3 6 cable upstream 2 modulation-profile 221 cable upstream 2 attribute-mask 20000000 no cable upstream 2 shutdown cable upstream 3 connector 7 cable upstream 3 frequency 33500000 cable upstream 3 channel-width 3200000 3200000 cable upstream 3 docsis-mode atdma cable upsteram 3 minislot-size 4 cable upstream 3 range-backoff 3 6 cable upstream 3 modulation-profile 221 cable upstream 3 attribute-mask 20000000 no cable upstream 3 shutdown end
Example: Non-Default Timer Configuration
The following example shows how to configure non-default timer configuration.
Router# show running-config | in timer cable rf-adapt timer general 60 cable rf-adapt timer candidate 15 cable rf-adapt timer relocation 5
Additional References
Related Documents
Related Topic |
Document Title |
---|---|
Cisco IOS commands |
|
CMTS cable commands |
http://www.cisco.com/en/US/docs/ios/cable/command/reference/cbl_book.htmlCisco IOS CMTS Cable Command Reference |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for Cable Modem Upstream RF Adaptation
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
![]() Note | The table below lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature. |
Feature Name |
Releases |
Feature Information |
---|---|---|
Cable Modem Upstream RF Adaptation |
12.2(33)SCF |
The Cable Modem Upstream RF Adaptation feature uses the per cable modem physical layer statistics to identify and automatically move cable modems to another logical upstream channel within the same physical port to prevent unnecessary channel-wide parameter changes. In Cisco IOS Release 12.2(33)SCF, this feature was introduced on the Cisco uBR10012 router and Cisco uBR7200 series routers. The following sections provide information about this feature: The following commands were introduced or modified: cable rf-adapt timer, cable upstream rf-adapt(logical channel), cable upstream rf-adapt, cable upstream threshold rf-adapt, show cable modem rf-adapt, show cable rf-adapt, cable upstream threshold hysteresis, cable upstream threshold, show cable modem, show cable modem access-group, show cable modem calls, show cable modem connectivity, show cable modem counters, show cable modem docsis version, show cable modem domain-name, show cable modem errors, show cable modem flap, show cable modem ipv6, show cable modem mac, show cable modem maintenance, show cable modem offline, show cable modem phy, show cable modem primary channel, show cable modem registered, show cable modem rogue, show cable modem summary, show cable modem type, show cable modem unregistered, show cable modem vendor, show cable modem wideband. |