Usage Guidelines

This command enables the use of Layer 2 tunnels on all cable and ATM interfaces in the router—which in turn allows you to map cable modems, on the basis of their hardware (MAC) addresses, to particular PVCs on an ATM interface—using the cable vc-map command.

Usage Guidelines

The Cisco CMTS routers support only the configuration of a single L2VPN NSI per CMTS.

This command supports the following interface types:

• Cisco uBR100012 Universal Broadband Router—Gigabit Ethernet.
• Cisco uBR7246VXR Universal Broadband Router—Fast Ethernet or Gigabit Ethernet

Usage Guidelines

This command enables the use of Layer 2 tunnels, using IEEE 802.1Q VLAN tagging, on all cable interfaces in the router. This in turn allows you to map traffic to and from cable modems, on the basis of the modems’ hardware (MAC) addresses, to a particular VLAN on a particular WAN interface, using the cable dot1q-vc-map command.

Usage Guidelines

You must enable MPLS tunnel traffic on the network side interface using the cable l2-vpn-service xconnect command before provisioning MPLS pseudowires.

Usage Guidelines

The cable l2-vpn-service xconnect nsi dot1q interface port-channel command configures the port-channel uplink port for DOCSIS L2VPN.

Usage Guidelines

• This feature is applicable only for DOT1Q L2VPN and not Multiprotocol Label Switching (MPLS) L2VPN.

• This feature is configurable when both the DOT1Q NSI ports are UP.

Usage Guidelines

You can perform a switchover only to an available member in the redundancy group. That is, if the member being specified in the xconnect backup force-switchover command is not available, the command will be rejected.

Usage Guidelines

Mobility subnets should match with the IPv4 or IPv6 address configured on the bundle or sub-bundle interface.

If the IPv4 or IPv6 address does not match, the following warning message is displayed:

Mobility IP should match the IDB subnet!

If you remove the IPv4 or IPv6 address from the interface, the mobility scope is removed for the IP address and the following warning message is displayed.

IPv6 2001:40:3:111::1 removed from Mobility subnets on Bundle1

Usage Guidelines

This command enables or disables the timer to reset the cable modem in partial service mode. It is recommended that a value of 120 or greater to be used for the timer.

Usage Guidelines

This command enables or disables the software reset option in the normal LCHA scenario. It is only applicable to Docsis 3.1 Downstream Module with Micro firmware version 3.16 and higher.

Usage Guidelines

The automatic ROMMON downgrade is disabled by default on all line cards, and we recommend that you do not change this default behavior.

Usage Guidelines

To perform automatic ROMMON upgrade on the cable interface line card, use the cable linecard auto-rommon-upgrade command to enable automatic ROMMON image upgrade on the line card and then reload the line card.

Usage Guidelines

The PRE powers off the Cisco uBR-MC3GX60V line card if any of the device temperatures on the line card exceeds the critical threshold value. To disable this power off feature, user should configure the no cable linecard critical-event-poweroff command and save the configuration.

The temperature thresholds for the devices on the Cisco uBR-MC3GX60V line card are:

Router#show environment subslot 6/0
------------------------------------------------------------------------
TEMPERATURE/POWER INFORMATION
------------------------------------------------------------------------
Number of Temperature Sensors : 9
Sampling frequency            : 2 minutes
------------------------------------------------------------------------
Sensor       | ID | Current     | Minor | Major | Critical | Alarm     |
             |    | Temperature |       Threshold          | Condition |
             |    |     degC      |          degC              |           |
------------------------------------------------------------------------
Nickel 10G     1       69          84     89       94        Normal  
Inlet #1       2       47          64     69       74        Normal  
CPU            3       68          86     91       96        Normal  
Raven          4       46          64     69       74        Normal  
Santana        5       36          57     62       67        Normal  
Coldplay       6       63          73     78       83        Normal  
Waxbill        7       76          85     90       95        Normal  
Fauna          8       70          77     82       87        Normal  
Fluorine       9       62          70     75       80        Normal  
------------------------------------------------------------------------
Power: 146.216 watts

Usage Guidelines

The group parameters in the cable load-balance d20-ggrp-default command can be set as default values.

Usage Guidelines

For renew keyword, the command executes as follows:

• If the reserved group range (0xff00 to 0xffff) has not been used for any GLBG, a new GLBG is created for the current fiber node.
• If the reserved group range has been used for any GLBG, the existing GLBG is removed and a new GLBG is created for the current fiber node configuration.
• If the reserved group ID has been used for a restricted load balancing group (RLBG), the command fails with a warning message.

For update keyword, the command executes as follows:

• If the reserved group range (0xff00 to 0xffff) has not been used for any GLBG, a new GLBG is created for that fiber node.
• If the reserved group range has been used for any GLBG, the GLBG is updated for the current fiber node configuration.
• If the reserved group ID has been used for a restricted load balancing group (RLBG), the command fails with a warning message.

This command is associated with Auto-generate DOCSIS 2.0 GLBG feature.

Usage Guidelines

The group parameters in the cable load-balance d30-ggrp-default command can be set as default values.

Usage Guidelines

When the no cable load-balance docsis-enable command is configured, cable modems do not participate in the load balancing operation after they are assigned to the correct Load Balancing Group (LBG).

However, the no cable load-balance docsis-enable command does not prevent the cable modems from moving to the correct LBG, therefore, the show cable load-balance docsis-group pending and show cable load-balance commands may display the movement of the cable modems while they are being assigned to the correct LBG. This is an expected behavior.

Usage Guidelines

Please provide some usage guidelines.

When the no cable load-balance docsis20-enable command is configured, cable modems which are narrow-band online does not participate in the load balancing operation after the correct Load Balancing Group (LBG) is assigned.

Usage Guidelines

Use the downstream-only keyword to enable only the downstream load balancing. When the downstream-only keyword is used, upstream load balancing is disabled.

Usage Guidelines

When the cable load-balance docsis30-enable dynamic downstream command is configured, cable modems which are wide-band online participates in the dynamic downstream utilization based on load balancing operation after the correct Load Balancing Group (LBG) is assigned.

Usage Guidelines

When the cable load-balance docsis30-enable static command is configured, cable modems which are wide-band online does not participate in the static modem count based load balancing operation after the correct Load Balancing Group (LBG) is assigned.

Usage Guidelines

Before configuring the DOCSIS 3.0 dynamic load balancing on Cisco CMTS, you need to enable DOCSIS 2.0 and DOCSIS 3.0 load balancing on CMTS.

Usage Guidelines

The cable load-balance docsis-group command creates a DOCSIS LBG with the specified number and then enters the config-lb-group configuration mode. Use the config-lb-group configuration mode to configure the DOCSIS LBG.

• disable
• docsis-policy
• downstream
• init-tech-list
• init-tech-ovr
• interval
• method
• policy
• restricted
• service-type-id
• tag
• threshold
• upstream

Usage Guidelines

This command associates a rule with a policy. A policy is created only when a rule is associated with it. Similarly, the policy is removed if you remove the last rule associated with the policy.

Usage Guidelines

The cable load-balance exclude command allows you to specify that particular cable modems should not participate in one or more types of load-balancing operations. This might be done for cable modems that are currently provisioned for premium services, for cable modems that do not respond appropriately to upstream channel change (UCC) or channel override messages, or for other reasons.

In particular, you must use the cable load-balance exclude command to exclude cable modems that require specific upstream channels or downstream frequencies. Load balancing cannot be done when cable modems are assigned specific channels or frequencies in their DOCSIS configuration files.

The load balancing process has two phases.

• Assignment phase:

  When a modem is coming online in the assignment phase, the modem is moved to the load balance group by assigning it a load balancing group (LBG) ID. The assignment phase occurs only when a modem is coming online. Use the assignment option to exclude a modem during the assignment phase.

• Balancing phase:

  In the balancing phase, a modem is re-assigned to an LBG to balance the load. Use the static option to exclude a modem from static load balancing, the enforce , or strict options from dynamic load balancing, in the balancing phase.

You can use the cable load-balance exclude command to specify that these cable modems should not participate in the following types of load-balancing operations:

• Static load balancing—Load balancing is done at the time a cable modem registers by specifying the proper target channel in the Downstream Frequency Override or an Upstream Channel ID Override field in the registration response (REG-RSP) message that the Cisco CMTS sends to the cable modem. This is the default form of registration-based load balancing.
• Passive load balancing—Load balancing is done at the time a cable modem registers by ignoring a cable modem’s registration request (REG-REQ) message until it uses the correct target channels. Use the cable load-balance exclude command to specify this form of load balancing for older cable modems that do not respond well to the active form of load balancing.

  Note	Passive load balancing is not supported on cBR Series Converged Broadband Routers.

• Dynamic load balancing—A form of traffic-based load balancing, in which cable modems are balanced among upstreams and downstreams after they come online, while they are passing traffic. (Dynamic load balancing is enabled using the enforce option with the cable load-balance group threshold command.)

Use the cable load-balance exclude command to exclude a cable modem from any combination of load-balancing operations. The table below shows which forms of load-balancing operations are excluded and which are enabled for each form of the cable load-balance exclude command:

Note

Excluding cable modems might be required for some cable modems that are not DOCSIS-compliant. Such cable modems can go offline for long periods of time when load balancing is attempted using DOCSIS MAC messages. If this is the case, use the cable load-balance exclude command to exclude such cable modems from load-balancing operations until the modem can be upgraded to DOCSIS-compliant software.

Effective with Cisco IOS Release 12.2(33)SCH, you can configure the cable load-balance exclude command once to exclude all the STBs, that do not support load balancing, using the mask argument. You can also move cable modems that were moved to a load balancing group in assignment phase, using the assignment option.

Usage Guidelines

The cable load-balance group command is used to configure the following features:

• IGMP-Triggered Dynamic Channel Change Load Balancing for DOCSIS 2.0 Cable Modems
• Load Balancing and Dynamic Channel Change on the Cisco CMTS Routers
• Restricted/General Load Balancing and Narrowband Dynamic Bandwidth Sharing with Downstream Dynamic Load Balancing

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.

Tip	In a system with balanced loads, the interfaces will contain the same number of cable modems only when the interfaces are configured with the same modulation parameters.

Service Flow Method

The service-flows method of load balancing uses the number of active service flow IDs (SFIDs) on an interface to determine the current load. This is a form of distribution-based load balancing, in which the absolute numbers of service flows are used to determine whether interfaces are load balanced.

This method does not take into account the amount of traffic flowing on each SFID, 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 SFIDs. This means that when interfaces are using different channel widths or modulation profiles, the system can assign different numbers of SFIDs to the interfaces to achieve a balanced load. For example:

• Channel widths— For example, 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 SFIDs to the second upstream, because its channel width is twice as large as the first upstream’s channel width.
• Modulation profiles— For example, 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 SFIDs 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.

Tip	In a system with balanced loads, the interfaces will contain the same number of SFIDs only when the interfaces are configured with the same modulation parameters.

Utilization Method

The utilization method uses an interface’s current percentage of utilization to determine the current load. This method uses the amount of traffic being sent over an interface, in the form of the percentage of total bandwidth being used. (To avoid unnecessary movement of cable modems, the utilization method does not perform load balancing until an interface is at least 25 percent of utilization.)

Note

Do not use the utilization method of load balancing on cable interfaces that have a small number of cable modems and where a single modem is responsible for the majority of the interface load. In this condition, the Cisco CMTS could end up continually moving cable modems from one interface to another in an endless attempt to load balance the interfaces. To avoid this, configure the utilization threshold to a value that is higher than what can be caused by any single cable modem.

When using the utilization method, the system takes into account the relative throughput and bandwidth (as determined by the modulation profiles and channel widths) of each interface when evaluating the load on those interfaces. For example, if two upstreams are being load-balanced using the utilization method, and the first upstream has twice the bandwidth of the second upstream, the two upstreams are considered balanced when they reach the same percentage of utilization. The first upstream is carrying more traffic than the second upstream because it has a larger capacity for traffic, but the percentage of utilization will be the same.

Note

Certain conditions can cause a system instability that could result in the Cisco CMTS endlessly attempting to load balance the interfaces. For example, this situation could occur in noisy environments, where cable modems drop offline on a regular basis, or when cable modems are repeatedly trying to register because the provisioning system has sent them the wrong DOCSIS configuration files. If the Cisco CMTS detects such unstable situations, it does not load balance cable modems from those interfaces until the system stabilizes. However, if the system instability persists, you should increase the threshold values using the cable load-balance group threshold command until you can solve the stability problems.

Use the no form of this command to delete a load-balance group. Deleting a load-balance group also automatically removes all upstream and downstream channel associations that were made with that group using the cable load-balance and cable upstream load-balance commands.

Tip	To exclude individual cable modems from one or more types of load balancing, use the cable load-balance exclude command.

Usage Guidelines

The cable load-balance group command is used to configure the following features:

• IGMP-Triggered Dynamic Channel Change Load Balancing for DOCSIS 2.0 Cable Modems
• Load Balancing and Dynamic Channel Change on the Cisco CMTS Routers
• Restricted/General Load Balancing and Narrowband Dynamic Bandwidth Sharing with Downstream Dynamic Load Balancing

After you have used the cable load-balance group (global configuration) command to initially create and configure a load balance group, use the cable load-balance group (interface configuration) command to assign this load balance group to a downstream. This enables the cable interface to begin participating in load-balancing operations.

Tip	Use the cable upstream load-balance group command to assign this load balance group to an upstream.

The following rules apply when creating and assigning load balance groups:

• A downstream or upstream can belong to only one load balance group.
• All downstreams and upstreams in a load balance group must share physical radio frequency (RF) connectivity to the same group of cable modems. Downstreams can be in a separate load balance group than upstreams, but all downstreams or all upstreams that have the same RF physical connectivity must be members of the same load balance group. You cannot distribute downstreams or upstreams that share physical connectivity across multiple load balance groups.

Note	If both downstreams and upstreams are assigned to the same load balance group, the Cisco CMTS attempts to balance both the downstream and upstream values when it moves cable modems.

• If the load balance group includes downstream interfaces, you must also configure the downstream center frequency on those interfaces, using the cable downstream frequency cable interface command. This command is informational-only on cable interfaces that use an external upconverter, but it is required for load balancing, so that the Cisco CMTS knows where to move cable modems when it is load balancing downstreams.
• Load balancing is done only on a per-chassis basis—all interfaces in a load balance group must be in the same chassis.

Note

In Cisco IOS Release 12.2(15)BC1, you can configure an interface for both load balancing and Hot-Standby Connection-to-Connection (HCCP) N+1 redundancy, but load balancing does not continue after a switchover from a Working to a Protect interface. Load balancing resumes when the Cisco CMTS switches back to the Working interface.

Usage Guidelines

This command is subject to the restrictions and prerequisites described in Configuring Load Balancing and Dynamic Channel Change (DCC) on the Cisco CMTS .

Usage Guidelines

The cable load-balance group interval command is used to configure the following feature:

• Load Balancing and Dynamic Channel Change on the Cisco CMTS Routers

To perform load balancing, the Cisco CMTS must determine the actual load on an interface on a periodic basis. This frequency of the updates also determines how frequently cable modems can be moved to achieve balanced loads. One cable modem, at most, is moved during each update period.

The more often these updates are performed, the more accurate the Cisco CMTS can be in performing its load balancing operations. As a general rule, begin with the default frequency value, and then adjust the value accordingly, in small increments, as load balancing conditions or performance levels might require. The default interval value was changed in Cisco IOS Release 12.2(33)SCF to reduce thrashing of cable modems when utilization-based method is used with DOCSIS load balancing.

Note

Having too small an interval could result in cable modems being constantly moved to achieve balanced loads during peak usage times when load balance could spike to transient heavy traffic. Also, more frequent updates can have a performance impact, especially on routers with a large number of active interfaces and cable modems.

Usage Guidelines

This command is subject to the restrictions and prerequisites described in Configuring Load Balancing and Dynamic Channel Change (DCC) on the Cisco CMTS .

Cisco IOS Release 12.2(17b)BC4 enables the optional operation of making downstream load balancing decisions as follows:

• The target downstream segment is in the same downstream load balancing group as the source downstream segment.
• The upstream load balancing group can be set for the corresponding channel on which a cable modem is balanced.
• The Cisco CMTS automatically locates the upstream segment for a load balancing group and processes the upstream group status on the source interface that has the lowest load.
• The target downstream segment must have an upstream channel set in the upstream load balancing group.
• The highest target upstream segment must carry less load than any other potential target —the highest upstream segment on other interfaces.

This command enables an alternative downstream load balancing scheme that makes use of per-upstream loads rather than total downstream loads.

This enhancement performs downstream load balancing that accounts upstream channel loads 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 together.

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 optional configuration supports output of the show cable load-balance command so that the command displays more information about loads on channels that are configured on external or remote cable interface line cards.

Usage Guidelines

The cable load-balance group policy ugs command determines whether a load-balance group can move cable modems with UGS service flows, so as to enforce dynamic load balancing policies. Because most voice calls use UGS service flows to allow real-time traffic, this option is primarily used to determine whether the Cisco CMTS will move cable modems with active voice calls.

If you disable this option (no cable load-balance group policy ugs ), the Cisco CMTS does not move cable modems with active UGS service flows to a new upstream or downstream. This prevents some possible interruptions of service to these customers, but it could result in denial of service conditions for other customers if the interface starts becoming overloaded.

To avoid this, the default configuration (cable load-balance group policy ugs ) of this command allows the Cisco CMTS to move cable modems to a new upstream or downstream, even if they have active UGS service flows. This enables the Cisco CMTS to perform optimum load balancing, but it could cause a momentary interruption in the voice call—users on the voice call might hear a momentary drop during the call, but the call should not be terminated.

Note	The cable load-balance group policy ugs command affects only dynamic load-balancing operations and does not affect static and passive load-balancing operations. Dynamic load balancing is enabled using the enforce option with the cable load-balance group threshold command.

Usage Guidelines

The cable load-balance group threshold command is used to configure the following feature:

• Load Balancing and Dynamic Channel Change on the Cisco CMTS Routers

The cable load-balance group threshold command configures a load-balance group for the threshold values that it should use to determine when a cable modem should be moved to a new downstream or upstream. You can specify the following different thresholds:

• load —Specifies the maximum load usage that can exist between interfaces in a load-balance group before the Cisco CMTS begins static load-balancing operations. The default value of load-value is 10 percent, which means that two upstreams or two downstreams can have usage rates that vary up to 10 percent before the Cisco CMTS begins rebalancing the load usage. This rebalancing, however, is done only when cable modems first register with the Cisco CMTS—the Cisco CMTS does not switch cable modems that are already online.

For example, if the load value is 10 percent, and upstream 1 is at 23 percent and upstream 2 is at 30 percent, no cable modems are moved. However, if load usage for upstream 2 reaches 35 percent, the Cisco CMTS begins assigning new cable modems, as they register, to upstream 1 until the difference in load usage between the two upstreams falls below 10 percent.

Note	The default of 10 percent is the minimum recommended threshold. Do not set this threshold below 10 percent unless you have been instructed to do so by Cisco TAC.

• enforce —Enables dynamic load balancing, so that the Cisco CMTS can move cable modems that are already online. This option has its own threshold value, which specifies the difference in load usage that must exist between two interfaces in a group before the Cisco CMTS begins moving online cable modems. The Cisco CMTS continues to move cable modems until the difference in load usage rates falls below the threshold value.

When using dynamic load balancing and an upstream channel is overloaded, the Cisco CMTS sends an Upstream Channel Change (UCC) request to a cable modem to instruct it to move to another upstream. The cable modem should move to the new upstream channel, without going offline or having to reregister with the CMTS.

When using dynamic load balancing and a downstream channel is overloaded, the Cisco CMTS sends an stop response to a cable modem’s ranging request (RNG-REQ) message. When the cable modem sends a new REG-REQ message, the Cisco CMTS specifies the new downstream channel in the Downstream Frequency Override field in its REG-RSP message. The cable modem must go offline and reregister on the new downstream channel, so as to conform to the DOCSIS 1.0 specifications.

Note

In Cisco IOS Release 12.2(15)BC1, the dynamic load balancing method results in cable modems going offline and having to reregister whenever the modems are moved between downstreams. This is because the DOCSIS 1.0 specification requires cable modems to reregister whenever the downstream is changed using the Downstream Frequency Override message. Cable modems should not go offline when moved between upstreams.

The Cisco CMTS also continues to enforce the load threshold value to perform static load balancing as well. Therefore, the threshold percentage should be equal to or greater than the percentage specified with the load load-value option.

For example, if you specify load 10 enforce 15 , the Cisco CMTS monitors the load usage between cable interfaces in the load-balance group. If upstream 1 reaches 33 percent and upstream 2 reaches 45 percent, the Cisco CMTS begins static load-balancing operations by assigning new cable modems to upstream 1 when they register. If the difference still continues to grow, and upstream 2 reaches 50 percent, the Cisco CMTS also begins dynamic load-balancing operations by moving online cable modems, until the difference in load usage falls below 15 percent. The Cisco CMTS then continues static load-balancing operations until the difference falls below 10 percent.

Tip	The enforce threshold is not displayed in the configuration file if it is the same as the load threshold. For example, if you enter the cable load-balance group 1 threshold load 50 enforce 50 command, it appears as cable load-balance group 1 threshold load 50 enforce in the configuration file.

• load minimum —Specifies that cable modems should be moved only if the load between the two interfaces is greater than the specified number of cable modems or service flows. This option is valid only when you have configured the load-balance group using either the method modem or method service-flows options with the cable load-balance group command. It is not used with the utilization method.
• stability —Specifies the minimum percentage of ranging requests that are successful before the Cisco CMTS determines that the interface or channel is unstable. When the channel has fewer than this percentage of cable modems responding to periodic ranging requests over a one-minute period, the Cisco CMTS begins moving modems to other channels in the load-balance group. For example, when set to 75 percent, the Cisco CMTS begins moving modems when fewer than 75 percent of modems are replying to ranging requests.
• ugs —Specifies a threshold for when the Cisco CMTS should move cable modems that have active UGS service flows, which are typically used for active voice calls. This option goes into force only when dynamic load balancing has been enabled (using the enforce option), and the Cisco CMTS has been allowed to move cable modems with active UGS service flows (using the cable load-balance group policy ugs command). The band-value threshold specifies the maximum usage of UGS service flows that should exist before the Cisco CMTS begins moving calls.

For example, if the band-value threshold is at its default of 70 percent, the Cisco CMTS does not begin moving cable modems with active UGS service flows until UGS usage on an upstream or downstream reaches 70 percent of the total available bandwidth. The Cisco CMTS continues moving cable modems that are online with active UGS service flows until the UGS usage on the interface falls below 70 percent.

Note

Certain conditions can cause a system instability that could result in the Cisco CMTS endlessly attempting to load balance the interfaces. For example, this situation could occur in noisy environments, where cable modems drop offline on a regular basis, or when cable modems are repeatedly trying to register because the provisioning system has sent them the wrong DOCSIS configuration files. If the Cisco CMTS detects such unstable situations, it does not load balance cable modems from those interfaces until the system stabilizes. However, if the system instability persists, you should increase the threshold values using the cable load-balance group threshold command until the system stabilizes.

Usage Guidelines

In Cisco IOS releases prior to Cisco IOS Release 12.3(17a)BC, the load balancing default setting is UGS. This is not the case with Cisco IOS Release 12.3(17a)BC. In this latter release, and subsequent releases, configuration is required if the cable modems with active UGS flows are desired to participate in load balancing.

This command is subject to the restrictions and prerequisites described in Configuring Load Balancing and Dynamic Channel Change (DCC) on the Cisco CMTS .

The cable load-balance group threshold command is used to configure the following feature:

• Load Balancing and Dynamic Channel Change on the Cisco CMTS Routers

Usage Guidelines

The cable load-balance rule rule-id disable-period dis-start start-time dis-period disable-period command can be used for a 24 hours period.

Important

You cannot disable load balancing and enable it for the next day using a single rule. You must configure two separate rules using the cable load-balance rule rule-id disable-period dis-start start-time dis-period 0 command to disable it and the cable load-balance rule rule-id disable-period dis-start 0 dis-period disable-period command to enable it for the next day.

The no form of this command supports the following actions:

• Remove a defined rule.
• Remove the rule from all policies.
• Remove the policy itself if it is the last rule of that policy.

Note	Static multicast groups must be configured on the specific bundle interface as well as on the correct forwarding interfaces to enable the vdoc-enabled rule.

Usage Guidelines

When you set cable modem delay time to 0, successful registration triggers static load balancing instantly after registration hold off time ends.

Usage Guidelines

The cable source-verify command enables service providers to verify that the IP addresses being used on the cable interface have been properly assigned by the provider’s DHCP servers. When a bad IP address is detected, the Cisco CMTS generates a BADIPSOURCE error message in the console logs.

In previous Cisco IOS releases, the Cisco CMTS generated these particular error messages for every IP packet that contained a bad IP source address. This can create a large volume of error messages that can make it difficult to see other error messages in the console logs.

To create a separate log for these error messages, use the cable logging badipsource command. You can also specify the size of the buffer that contains these error messages. When the buffer becomes full, the oldest messages are deleted to make room for newer messages, so choose a buffer size that allows you to retain all messages until you can examine them.

On the Cisco uBR10012 router, this command includes only the BADIPSOURCE error messages generated by the PRE module. The cable interface line cards also generate their own error messages, but because these error messages are typically duplicates of the ones generated by the PRE module, they are not included in the separate log.

Tip

If you find that the current buffer is too small to contain the current volume of error log messages, you can issue this command again with a larger buffer size. However, doing so automatically clears out all messages currently in the buffer, so ensure that you have viewed all the current messages before giving a second cable logging badipsource command.

Note	Be cautious when specifying the buffer size, because the Cisco CMTS could run out of memory for other tasks. Use the show memory EXEC command to display the maximum available processor memory, and set the buffer size for this command to a value well within that maximum value.