Guidelines for Configuring Dynamic CoS for Subscriber Access

This topic describes the hardware requirements and guidelines for configuring dynamic CoS in a subscriber access environment.

Hardware Requirements for Dynamic CoS

Table 1 lists the hardware requirements based on subscriber interface type for the hierarchical scheduling and per-unit scheduling dynamic CoS configurations.

Configuration Guidelines for Dynamic Scheduling and Queuing

• To improve CoS performance in IPv4, IPv6, and dual-stack networks that use a DHCP access model, we recommend that you use the aggregate-clients replace statement rather than the aggregate-clients merge statement.

• You can configure dynamic CoS with one of the following scheduling configurations:

  • For hierarchical scheduling configurations, you must enable hierarchical scheduling in the static CLI for the interface referenced in the dynamic profile. If not, the dynamic profile fails.
  • For per-unit scheduling configurations, you must enable per-unit scheduling in the static CLI for the interface referenced in the dynamic profile. If not, the dynamic profile fails and schedulers are not attached to the interface.
• You configure the traffic scheduling and shaping parameters in a traffic-control profile within the dynamic profile. You can configure the scheduler map and schedulers in a dynamic profile or in the [edit class-of-service] hierarchy. You must statically configure the remaining CoS parameters, such as hierarchical scheduling, classifiers, drop profiles, and forwarding classes, in the [edit class-of-service] hierarchy.
• You can configure only one traffic-control-profile under a dynamic profile.
• You must define the output-traffic-control-profile that binds the traffic-control profile to the interface within the same dynamic profile as the interface.
• We recommend that you provide different names for the schedulers defined in dynamic profiles that are used for access and services. For example, if there are two dynamic profiles, voice-profile and video-profile, provide unique names for the schedulers defined under those profiles.
• You must use a service dynamic profile with a different profile name for each RADIUS CoA request over the same logical interface.
• When you configure scheduler and scheduler map sharing in client profiles, schedulers and scheduler maps must use the unique ID format. If the client profile uses the unique ID format and you want to have either scheduler or scheduler map sharing for service activation, you must configure the service profile in unique ID format.

Configuration Guidelines for Dynamic Classifiers and Rewrite Rules

• To apply classifiers and rewrite rules to a subscriber interface in a dynamic profile, you must configure the rewrite rule and classifier definitions in the static [edit class-of-service] hierarchy and reference them in the dynamic profile.
  • If a static classifier or a rewrite rule definition that is referenced by a dynamic subscriber interface does not exist, the configuration is invalid and the subscriber cannot log in.
  • If a network administrator changes the static classifiers and rewrite rules definitions that are referenced in a dynamic profile with an active subscriber interface logged in, the changes are applied to the active subscriber interface immediately.
  • If a network administrator deletes a classifier or a rewrite rule definition that is referenced by an active dynamic subscriber interface, the system removes the classifier or rewrite rule binding from the interface. The classifier is replaced by the default classifier. If the network administrator adds the removed classifier or rewrite rule to the configuration while the dynamic interface is active, the addition does not take effect until the subscriber logs out and then logs in again.
• IP demux interfaces can only instantiate Layer 3 rules (both rewrite rules and classifiers).
  • An IP demux subscriber interface can implicitly inherit a classifier from the underlying interface. If an IP demux interface is created without a classifier and a Layer 2 classifier is attached to the underlying interface, the IP demux interface also inherits the Layer 2 classifier. The show class-of-service interface interface-name command does not display this attachment.

    Table 2 lists the classification rule configuration for an IP demux subscriber interface with a VLAN underlying interface.

    Table 2: IP Demux Classification Rules

    VLAN Underlying Interface Classifier Configuration	IP Demux Interface Classifier Configuration	Resulting Classifier Configuration
    Layer 2	—	VLAN Layer 2
    Layer 2	Layer 3	Demux Layer 3
    Layer 3	—	Default
    Layer 3	Layer 3	Demux Layer 3

  • An IP demux subscriber interface explicitly inherits Layer 2 rewrite rules from the underlying interface if a Layer 2 rewrite rule is present. The show class-of-service interface interface-name command displays the attachment.

    Table 3 lists the rewrite rule configuration for an IP demux subscriber interface with a VLAN underlying interface.

    Table 3: IP Demux Rewrite Rules

    VLAN Underlying Interface Rewrite Rule Configuration	IP Demux Interface Rewrite Rule Configuration	Resulting Rewrite Rule Configuration
    Layer 2	—	VLAN Layer 2
    Layer 2	Layer 3	VLAN Layer 2 and demux Layer 3
    Layer 3	—	Default
    Layer 3	Layer 3	Demux Layer 3

  • An L2TP subscriber interface can implicitly inherit a classifier from the underlying interface.

    Table 4 lists the classification rule configuration for an L2TP LAC subscriber interface with a VLAN underlying interface.

    Table 4: L2TP Classification Rules

    VLAN Underlying Interface Classifier Configuration	L2TP LAC Classifier Configuration	Resulting Classifier Configuration
    Layer 2 or Fixed	Layer 2 or Fixed	VLAN Layer 2 or Fixed
    Layer 2 or Fixed	Layer 3	Demux/PPPoE Layer 3
    Layer 3	Layer 2 or Fixed	VLAN Layer 2 or Fixed
    Layer 3	Layer 3	Demux/PPPoE Layer 3

  • An L2TP LAC subscriber interface explicitly inherits Layer 2 rewrite rules from the underlying interface if a Layer 2 rewrite rule is present. Table 5 lists the rewrite rule configuration for an L2TP LAC subscriber interface with a VLAN underlying interface.

    Table 5: L2TP LAC Rewrite Rules

    VLAN Underlying Interface Rewrite Rule Configuration	L2TP Interface Rewrite Rule Configuration	Resulting Rewrite Rule Configuration
    Layer 2	Layer 2	VLAN Layer 2
    Layer 2	Layer 3	VLAN Layer 2 and demux/PPPoE Layer 3
    Layer 3	Layer 2	VLAN Layer 2 and demux/PPPoE Layer 3
    Layer 3	Layer 3	Demux/PPPoE Layer 3

Configuration Guidelines for Dynamic CoS on Specific Interface Types

• CoS for Aggregated Ethernet Subscriber Interfaces Overview
• CoS for L2TP LAC Subscriber Interfaces Overview
• CoS for L2TP LNS Inline Services Overview
• CoS for PPPoE Subscriber Interfaces Overview
• CoS for Interface Sets of Subscribers Overview