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Cisco IOS CMTS Cable Command Reference
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Introduction
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Cable Commands: a through cable-modem
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Cable Commands: cable a through cable c
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Cable Commands: cable d
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Cable Commands: cable e through cable i
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Cable Commands: cable l
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Cable Commands: cable m to n
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Cable Commands: cable p through cable r
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Cable Commands: cable s
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Cable Commands: cable t
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Cable Commands: cable u through cable w
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Cable Commands: ca through cr
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Cable Commands: d through h
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Cable Commands: i through p
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Cable Commands: q through sg
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Cable Commands: show a through show cable l
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Cable Commands: show cable m to show cable u
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Cable Commands: show ch through show cr
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Cable Commands: show d through show i
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Cable Commands: show m through show z
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Cable Commands: snmp through w
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Appendix A: Cable Debug Commands
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Appendix B: Cisco CMTS Router ROM Monitor Commands
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Feedback
Table Of Contents
Cable Commands: a through cable-modem
cable-modem downstream saved channel
cable-modem upstream preamble qpsk
cable-modem voip clock-internal
Cable Commands: a through cable-modem
Revised: July 2012, OL-15510-15
New Commands
Obsolete Commands
Replaced Commands
annex modulation
rf-channel frequency
12.3(23)BC
access-denied
To create a DOCSIS configuration file that disables network access to the customer premise equipment (CPE) devices that are attached to the cable modem (CM) on a Cisco CMTS router, use the access-denied command in cable config-file configuration mode. To enable access, use the no form of this command.
access-denied
no access-denied
Syntax Description
This command has no arguments or keywords.
Command Default
Access to the cable network is permitted (no access-denied).
Command Modes
Cable config-file configuration (config-file)
Command History
12.1(2)EC1
This command was introduced.
12.2(33)SCA
This command was integrated into Cisco IOS Release 12.2(33)SCA. Support for the Cisco uBR7225VXR router was added.
Usage Guidelines
This command sets the Network Access Control object in the DOCSIS configuration file. If the object is set to 1 (set by the default of no access-denied), the CPE devices behind the CM allow access to the network. If the object is set to 0 (by configuration of the access-denied command) to disable network access for the CPE devices, the CM does not forward traffic from its attached CPE devices.
For normal operation, the CM must be set to allow access (the default). However, to deny service for reasons such as nonpayment or unauthorized use of services, the access-denied command can be used.
Examples
The following example shows how to disable network access for the CPE devices that are connected to the CM:
cable config-file disable.cmaccess-deniedRelated Commands
activate-rule at-byte-count
Note
Effective with Cisco IOS Release 12.3(9a)BC, the activate-rule at-byte-count command is not available in Cisco IOS software.
To specify the number of bytes that a subscriber can transmit during the monitoring period on a Cisco CMTS router, use the activate-rule at-byte-count command in enforce-rule configuration mode. To reset the rule to its default values, use the no form of this command.
activate-rule at-byte-count kbytes {downstream | upstream} [enforce]
no activate-rule at-byte-count kbytes {downstream | upstream} [enforce]
Syntax Description
Command Default
The kbytes value defaults to 0 (no limit), upstream direction, and enforce-rule QoS profiles are not automatically applied (no activate-rule at-byte-count enforce).
Command Modes
Enforce-rule configuration (enforce-rule)
Command History
Usage Guidelines
The activate-rule at-byte-count command specifies the maximum number of bytes that a subscriber can transmit during the monitor window period (see the monitoring-duration command). If a subscriber transmits traffic beyond this maximum value, the CMTS router considers the subscriber to be overconsuming.
If the optional enforce keyword has been specified for an enforce-rule, the CMTS router automatically switches overconsuming subscribers to the enforced QoS profile (see the qos-profile enforced command). The enforced QoS profile remains in force during the penalty time period (see the qos-profile registered command).
An enforce-rule can be created for only one direction, either upstream or downstream. To activate subscriber traffic management for both the upstream and downstream directions, create two different enforce-rules, with one rule's activate-rule-at-byte-count command specifying the downstream direction and the other rule specifying the upstream direction.
When you change the configuration of a currently active enforce-rule, that rule begins using the new configuration immediately to manage the cable modems tracked by the enforce-rule.
Note
Examples
The following example shows a typical activate-rule-at-byte-count command for the downstream direction:
Router# configure terminalRouter(config)# cable qos enforce-rule residentialRouter(enforce-rule)# activate-rule at-byte-count 20 downstreamThe following example shows a typical activate-rule-at-byte-count command for the upstream direction. The enforce option is also added so that the enforce-rule QoS profile is automatically applied to users who exceed their registered profile:
Router# configure terminalRouter(config)# cable qos enforce-rule testRouter(enforce-rule)# activate-rule at-byte-count 5 upstream enforceThe following example shows the same command being given for a second enforce-rule. The system rejects the command because it is a duplicate of an existing rule, using the same QoS profile and direction. You must change at least one of the rule parameters to make it unique before it is mapped and applied to service flows.
Router# configure terminalRouter(config)# cable qos enforce-rule test2Router(enforce-rule)# activate-rule at-byte-count 5 upstream enforceEnforce-rule test2 won't be mapped to service flows as it is duplicate of test1 with same registered qos-profile 5 and same directionRelated Commands
annex modulation
Note
To set the annex (MPEG framing format) and modulation for the Wideband SPA, use the annex modulation command in controller configuration mode. To set the annex to B and the modulation to 64 QAM, use the no form of this command.
annex {A | B} modulation {64qam | 256qam} [rf-start-index rf-end-index]
no annex {A | B} modulation {64qam | 256qam} [rf-start-index rf-end-index]
Syntax Description
Command Default
No annex or modulation is set for the Wideband SPA.
Command Modes
Controller configuration
Command History
Usage Guidelines
Use this command to set the following on a Wideband SPA:
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Each Wideband SPA supports up to 24 RF channels depending on how the SPA is configured with the annex modulation command.
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The rf-start-index and rf-end-index arguments are intended for future use and are not currently needed. If rf-start-index and rf-end-index are not specified, the default values are as follows:
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Examples
The following example shows how to set the MPEG framing format and modulation for the Wideband SPA located at slot 1, subslot 0, bay 0:
Router(config)# controller modular-cable 1/0/0Router(config-controller)# annex B modulation 64qamRelated Commands
application-id
To specify an application type to allow admission control to be applied to a group configuration, use the application-id command in multicast QoS configuration mode. To disable admission control, use the no form of this command.
application-id number
no application-id number
Syntax Description
number
Specifies the application identification number of the multicast QoS group. The valid range is 1-65535.
Command Default
Multicast QoS group application type is not identified.
Command Modes
Multicast QoS configuration (config-mqos)
Command History
Usage Guidelines
In order to enable intelligent multicast admission control, you must enable and configure an application type using the application-id command.
Examples
The following example identifies a multicast QoS group application ID using the applicaton-id command:
Router(config)# cable multicast qos group 20 priority 55 globalRouter(config-mqos)# application-id 44Related Commands
attributes
To configure the attribute value for an upstream bonding group, use the attributes command in upstream bonding configuration submode. To restore the default attribute value, use the no form of this command.
attributes value
no attributes
Syntax Description
value
The upstream bonding group attibute value, in hexadecimal format. The range is from 0 to FFFFFFFF. The default is 80000000.
Command Default
The upstream bonding group attribute value is 80000000.
Command Modes
Upstream bonding configuration (config-upstream-bonding)
Command History
Usage Guidelines
Note
Examples
The following example shows how to configure the attribute value for an upstream bonding group on a cable interface line card on the Cisco uBR10012 router:
Router# configure terminalRouter(config)# interface cable7/1/0Router(config-if)# cable upstream bonding-group 20Router(config-upstream-bonding)# attributes eeeeeeeeRelated Commands
cable upstream bonding-group
Creates an upstream bonding group on a cable interface.
auto-sync
To enable automatic synchronization of the configuration files in NVRAM, use the auto-sync command in main-cpu redundancy configuration mode. To disable automatic synchronization, use the no form of this command.
auto-sync {startup-config | config-register | bootvar | running-config | standard}
no auto-sync {startup-config | config-register | bootvar | standard}
Syntax Description
Defaults
For the Performance Routing Engines (PREs) on the Cisco uBR10012 universal broadband router, the system defaults to synchronizing all system files on the (auto-sync standard).
For the Supervisor Engines on the Cisco 7600 series routers, the system defaults to synchronizing the running configuration. (running-config).
Command Modes
Redundancy configuration (config-r)
Command History
Usage Guidelines
Cisco 7600 Series Routers
If you enter the no auto-sync standard command, no automatic synchronizations occur. If you want to enable any of the keywords, you have to enter the appropriate command for each keyword.
The auto-sync command is not supported in RPR+ mode.
Cisco uBR10012 Universal Broadband Router
By default, the system synchronizes all system files, which is the typical setting for most applications. However, you might want exclude certain files from synchronization for specialized applications.
For example, if you have configured the active and standby PRE1 (or PRE2) modules to run different versions of Cisco IOS software, you might want to use different configuration files as well. In this case, you would not synchronize the startup configuration file.
Examples
Cisco 7600 Series Routers
The following example shows how (from the default configuration) to enable automatic synchronization of the configuration register in the main CPU:
Router#configure terminalRouter (config)#redundancyRouter (config-r)#main-cpuRouter (config-r-mc)#no auto-sync standardRouter (config-r-mc)#auto-sync config-registerCisco uBR10012 Universal Broadband Router
The following example shows the system being configured to synchronize only the startup configuration file:
router(config)# redundancyrouter(config-r)# main-cpurouter(config-r-mc)# auto-sync startup-configrouter(config-r-mc)# exitrouter(config-r)# exitThe following example shows how to configure the system to synchronize all system files except for the startup configuration file. This typically is done when the two PRE1 (or PRE2) modules are running different software images.
router(config)# redundancyrouter(config-r)# main-cpurouter(config-r-mc)# no auto-sync startup-configrouter(config-r-mc)# auto-sync config-registerrouter(config-r-mc)# auto-sync bootvarrouter(config-r-mc)# exitrouter(config-r)# exitRelated Commands
redundancy
Enters redundancy configuration mode.
main-cpu
Enters main CPU redundancy configuration mode.
cable-modem compliant bridge
To enable DOCSIS-compliant bridging for the cable interface at startup, use the cable-modem compliant bridge command in cable interface configuration mode. To disable DOCSIS-compliant bridging, which is required to enable routing mode, use the no form of this command.
Cisco uBR904, uBR905, uBR924, uBR925 cable access routers, Cisco CVA122 Cable Voice Adapter
cable-modem compliant bridge
no cable-modem compliant bridge
Syntax Description
This command has no arguments or keywords.
Command Default
DOCSIS-compliant bridging is enabled by default.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
It is normally not necessary to enter this command in data-over-cable bridging applications because DOCSIS-compliant bridging is enabled by default. However, to configure the router for full transparent bridging or for routing mode, use the no form of the command and then configure the router as desired using the appropriate CLI commands.
Examples
The following example shows how to disable DOCSIS-compliant bridging on the cable interface:
Router# configure terminalRouter(config)# interface cable-modem 0Router(config-if)# no cable-modem compliant bridgeRouter(config-if)#Related Commands
cable-modem dhcp-proxy
To specify that a Dynamic Host Configuration Protocol (DHCP) server should provide an IP address for the router's Ethernet interface, for the loopback interface, or for the router's Network Address Translation (NAT) address pool, use the cable-modem dhcp-proxy command in cable interface configuration mode. To disable this feature so that you can then manually assign an IP address to the Ethernet interface or NAT address pool, use the no form of this command.
Cisco uBR905, Cisco uBR924, Cisco uBR925 Cable Access Routers, and Cisco CVA122 Cable Voice Adapter
cable-modem dhcp-proxy {interface ethernet number | interface loopback number | nat pool-name}
no cable-modem dhcp-proxy {interface ethernet number | interface loopback number | nat pool-name}
Note
Syntax Description
Command Default
No default behavior or values
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command is useful in three situations:
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When using this option, you must also use the following NAT configuration commands:
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After configuring the router with the cable-modem dhcp-proxy command, reboot the router. During the DOCSIS provisioning process, the router sends a DHCP client request to obtain an IP address for the cable interface.
The router then sends a proxy DHCP request to the DHCP server using the Ethernet interface's MAC address. The DHCP server replies with a second IP address that the router assigns to either the Ethernet or loopback interface, or to the NAT pool, depending on which option was used in the cable-modem dhcp-proxy command.
Note
Tip
Using NAT and DHCP Proxy and Copying Configuration Files
Most service providers typically create a standard configuration file for their cable modems, verify it, and then copy the working configuration as needed to other cable modems. This can cause problems when using the cable-modem dhcp-proxy command to create a NAT address pool for NAT/PAT translation.
The reason is that the default router configuration is for DOCSIS-compliant bridging, which includes two bridge-group 59 commands for each interface. To use the cable-modem dhcp-proxy command, you must put the router into routing mode, which means removing the bridge-group commands with the equivalent no bridge-group commands.
However, because no bridge-group is the default for these CLI commands, they are not saved in the running configuration. So when you save the Cisco IOS configuration file and copy it to other routers, the router is only partially configured for routing mode and continually resets its interfaces.
In addition, whenever you use the cable-modem dhcp-proxy command to create a NAT pool, the router automatically adds the appropriate ip nat pool commands to the configuration when it receives the actual IP addresses from the DHCP server. The IP addresses specified in this command are particular to each user and should not be copied to other routers.
To avoid this problem, use the following procedure to create a Cisco IOS configuration file that uses the cable-modem dhcp-proxy command to create a NAT address pool for NAT/PAT address translation:
Step 1
Step 2
Step 3
no bridge-group 59no bridge-group 59 spanning-disabledStep 4
For example, the following are the relevant lines in a typical DHCP proxy NAT configuration for a cable access router:
interface Ethernet0ip address 192.168.1.1 255.255.255.0ip nat insideload-interval 30!interface cable-modem0ip nat outsideload-interval 30no cable-modem compliant bridgecable-modem dhcp-proxy nat nat-pool!ip nat pool nat-pool 10.15.0.10 10.15.0.10 netmask 255.255.0.0When you copy this configuration file to the TFTP server, modify this portion of the configuration file to add the no bridge-group commands under each interface and to remove the ip nat pool command:
interface Ethernet0ip address 192.168.1.1 255.255.255.0ip nat insideload-interval 30no bridge-group 59no bridge-group 59 spanning-disabled!interface cable-modem0ip nat outsideload-interval 30no cable-modem compliant bridgecable-modem dhcp-proxy nat nat-poolno bridge-group 59no bridge-group 59 spanning-disabled!
Note
Examples
The following example shows how to configure the router so that it makes a proxy DHCP request to obtain an IP address for its Ethernet interface:
Router(config)# interface c0Router(config-if)# cable-modem dhcp-proxy interface ethernet 0The following example creates a NAT address pool with the IP address assigned by the DHCP server; this IP address must be in the network attached to the Ethernet address (which in this case is 192.168.100.0).
Router(config)# ip nat inside source list 1 pool net-208 overloadRouter(config)# interface cable0Router(config-if)# ip nat outsideRouter(config-if)# no cable compliant bridgeRouter(config-if)# cable-modem dhcp-proxy nat net-208Router(config-if)# exitRouter(config)# interface ethernet0Router(config-if)# ip address 192.168.100.94 255.255.255.0Router(config-if)# ip nat insideRouter(config-if)# exitRouter(config)# access-list 1 permit 192.168.100.0 0.0.0.255Router(config)#Related Commands
cable-modem compliant bridge
Enables DOCSIS-compliant transparent bridging for the cable interface at startup.
cable-modem downstream saved channel
To modify the saved downstream channel setting and upstream power value on the cable interface, use the cable-modem downstream saved channel command in cable interface configuration mode. To remove the saved settings, which will be saved at the next initialization cycle, use the no form of this command.
Cisco uBR904, uBR924 cable access routers
cable-modem downstream saved channel ds-frequency us-power
no cable-modem downstream saved channel ds-frequency us-power
Note
Syntax Description
ds-frequency
Downstream channel frequency in Hz, which can be from 91,000,000 to 860,000,000.
us-power
Upstream power level in decibels per millivolt (dBmV), which can be from 8 to 61.
Command Default
Enabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command is auto-generated by the operation of the cable MAC layer process. The DOCSIS RFI specification requires that CMs remember the downstream frequency and upstream power of the last successfully ranged session. These arguments are called up as the first downstream frequency and upstream power to use the next time the CM is booted. This operation dramatically speeds up the channel search.
Use the no cable-modem downstream saved channel ds-frequency us-power command to remove the saved frequency and power setting from the running configuration, which will be saved at the next initialization cycle.
To comply with DOCSIS requirements, Cisco IOS Release 12.1(2)T removed this command from the CLI for all platforms and reserved it for exclusive use by the DOCSIS provisioning process. This command exists in earlier Cisco IOS versions, but Cisco recommends that this command NOT be used by end users of Cisco cable CPE devices.
Examples
The following example shows how to remove the downstream frequency of 91,000,000 Hz and the upstream power level of 33 dBmV from the running configuration of a cable-modem interface:
Router(config)# interface cable-modem 0Router(config-if)# no cable-modem downstream saved channel 91000000 33Router(config-if)#Related Commands
cable-modem fast-search
To enable a faster downstream search algorithm on the cable interface, use the cable-modem fast-search command in cable interface configuration mode. To disable the downstream fast-search feature, use the no form of this command.
Cisco uBR904, uBR924 cable access routers
cable-modem fast-search
no cable-modem fast-search
Note
Syntax Description
This command has no arguments or keywords.
Command Default
Disabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This feature speeds up the frequency search performed by the cable access router. Normally it takes the cable access router about 30 to 50 seconds to sample 30 to 50 frequencies. The cable-modem fast-search command can reduce this search time. However, there might be some cases where this fast-search algorithm might not perform as well as the default algorithm. Trial and error is the only way to discover how well this feature works for your environment.
Examples
The following example shows how to enable the faster downstream search algorithm on the router's cable interface:
Router(config)# interface cable-modem 0Router(config-if)# cable-modem fast-searchRouter(config-if)#Related Commands
cable-modem qos drop-ack
To enable the automatic dropping of unnecessary TCP packet acknowledgements on the cable interface, use the cable-modem qos drop-ack command in cable interface configuration mode. To disable this feature, so that all TCP packet acknowledgements are sent, use the no form of this command.
Cisco uBR905, uBR924, uBR925 cable access routers, Cisco CVA122 Cable Voice Adapter
cable-modem qos drop-ack
no cable-modem qos drop-ack
Syntax Description
This command has no arguments or keywords.
Command Default
Enabled
Command Modes
Interface configuration and subinterface configuration (cable interface only)
Command History
Usage Guidelines
TCP traffic uses a packet-acknowledge algorithm, where a group of packets must be acknowledged before additional traffic can be sent. When a large number of packets is transmitted on the downstream, it can result in a large number of acknowledgements on the upstream. Because the downstream bandwidth is typically many times greater than the upstream bandwidth, certain applications can temporarily overrun the upstream with a large volume of acknowledgement packets.
If any of those acknowledgements are dropped or lost, traffic can be backed up, and data packets might have to be resent, even if those packets had in fact been successfully received. This can significantly impact real-time traffic, such as voice calls.
To optimize the TCP traffic on the upstream in these circumstances, the Cisco uBR905, Cisco uBR924, and Cisco uBR925 cable access routers and the Cisco CVA122 Cable Voice Adapters automatically analyze the upstream traffic and drop unnecessary packet acknowledgements when traffic begins backing up. This feature has been automatically enabled by default on the routers, starting with Cisco IOS Release 12.0(5)T.
In some situations, however, this feature can result in packets being dropped on the upstream, which could impact the performance of certain applications such as FTP transfers. If packet drops do occur on the upstream, this feature can be turned off with the no cable-modem qos drop-ack command.
Examples
The following example shows how to disable the TCP packet optimization feature on the cable interface, so that all TCP packet acknowledgements are sent:
Router(config)# interface cable-modem 0Router(config-if)# no cable-modem qos drop-ackRouter(config-if)#The following example shows how to enable the TCP packet optimization feature on the cable interface. This is the default configuration, so it does not need to be done unless it has been previously disabled.
Router(config)# interface cable-modem 0Router(config-if)# cable-modem qos drop-ackRouter(config-if)#Related Commands
show controllers cable-modem qos
Displays detailed information about the Quality of Service (QoS) configuration.
cable-modem upstream preamble qpsk
To enable the QPSK modulation scheme in the upstream direction from the cable interface to the CMTS, use the cable-modem upstream preamble qpsk command in cable interface configuration mode. To disable upstream modulation for the interface, use the no form of this command.
Cisco uBR904, uBR905, uBR924, uBR925 cable access routers, Cisco CVA122 Cable Voice Adapter
cable-modem upstream preamble qpsk
no cable-modem upstream preamble qpsk
Syntax Description
This command has no arguments or keywords.
Command Default
Enabled
Command Modes
Interface configuration (cable interface only)
Command History
Examples
The following example shows how to configure the cable interface for QPSK modulation on the upstream:
Router(config)# interface cable-modem 0Router(config-if)# cable-modem upstream preamble qpskRouter(config-if)#Related Commands
cable-modem voip best-effort
To allow voice calls to be sent upstream over the cable interface using best-effort quality of service (QoS), use the cable-modem voip best-effort command in cable interface configuration mode. To disable best-effort voice calls, use the no form of this command.
Cisco uBR924 cable access router
cable-modem voip best-effort
no cable-modem voip best-effort
Note
Syntax Description
This command has no arguments or keywords.
Command Default
Enabled
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command allows you to configure the voice traffic on a router to allow only calls having a high-priority service identifier (SID) to be connected.
If the dynamic configuration of high-priority queues for voice traffic fails, or if the far end cannot support the multiple SIDs and multiple classes of service required by high-priority traffic, the flag set by this command will be checked. If enabled (the default setting), the call will be allowed to go through. If disabled, the call will fail.
Examples
The following example shows how to disable best-effort voice calls:
Router(config)# interface cable-modem 0Router(config-if)# no cable-modem voip best-effortRouter(config-if)#Related Commands
cable-modem voip clock-internal
To enable the router's internal clock for Voice-over-IP (VoIP) calls, use the cable-modem voip clock-internal command in cable interface configuration mode. To disable the internal clock, so that it uses the clock from the cable interface for VoIP calls, use the no form of this command.
Cisco uBR924, uBR925 cable access routers, Cisco CVA122 Cable Voice Adapter
cable-modem voip clock-internal
no cable-modem voip clock-internal
Syntax Description
This command has no arguments or keywords.
Command Default
The default is to use the clock from the cable interface for VoIP calls.
Command Modes
Interface configuration (cable interface only)
Command History
Usage Guidelines
This command enables the internal clock, allowing it to make VoIP calls over the Ethernet and USB interfaces even when the cable interface is down or disconnected. If the CMTS is a Cisco uBR7200 series with a Cable Clock Card, this command disables the use of that clock.
This command can be used in both DOCSIS IP bridging and routing mode. However, when operating in DOCSIS IP bridging mode, VoIP packets are transmitted out only on the cable interface, so the router must be operating in routing mode to transmit voice packets out the Ethernet and USB interfaces.
Examples
The following example shows how to enable the internal clock for VoIP calls:
Router(config)# interface cable0Router(config-if)# cable-modem voip clock-internalRouter(config-if)#Related Commands
