Setting Shaping Rate and Overhead Accounting Based on PPPoE Vendor-Specific Tags
You can use access line parameters received in PPPoE discovery packets to set the shaping-rate and overhead-accounting class-of-service attributes on dynamic subscriber interfaces in a broadband access network. This feature is supported on MPC/MIC interfaces on MX Series routers.
The shaping rate is based on the Actual-Data-Rate-Downstream attribute.
The overhead accounting value is based on the Access-Loop-Encapsulation attribute and specifies whether the access loop uses Ethernet (frame mode) or ATM (cell mode).
You can configure class-of-service attributes, for example the shaping-rate, using the CLI, RADIUS vendor-specific attributes, ANCP, multicast, or in this case, PPPoE vendor-specific tags.
CLI Interaction with PPPoE Vendor-Specific Tags
When you enable this feature, the values supplied by the PPPoE
vendor-specific tags override the parameters that you have configured
in the CLI for the shaping-rate and overhead-accounting statements at the [edit dynamic-profiles profile-name class-of-service traffic-control-profiles] hierarchy level.
The shaping rate is based on the actual-data-rate-downstream attribute,
and is only overridden if the vs-tag value is less than the configured
value.
To enable this feature, include the dynamic-class-of-service-options statement at the [edit dynamic-profiles profile-name class-of-service] hierarchy level. Specify the appropriate
attribute as a value for the vendor-specific-tags option.
RADIUS Interaction with PPPoE Vendor-Specific Tags
When you enable this feature, the PPPoE vendor-specific tags override the dynamic configuration of the shaping-rate and overhead-accounting values in RADIUS vendor-specific attributes. The shaping-rate value is only overridden if the vs-tag value is less than the RADIUS value.
RADIUS CoA can overwrite the existing values. Upon receipt of a RADIUS CoA, the RADIUS value overrides the value set from the PPPoE vendor-specific tags.
PPPoE vendor-specific tags can override the RADIUS values, but a later RADIUS CoA request can then override that value.
ANCP Interaction with PPPoE Vendor-Specific Tags
You can mix ANCP and PPPoE vendor-specific tags on dynamic PPPoE interfaces, dynamically instantiated PPPoE interfaces, and ACI-sets. ANCP values override the PPPoE values. In this case, the ANCP shaping rate value overrides the PPPoE value.
Multicast QoS Adjustment Interaction with PPPoE Vendor-Specific Tags
Multicast QoS adjustments are not affected by this feature. The multicast adjustments adjust the shaping-rate set by PPPoE vendor-specific tags.
Shaping Rate Restrictions
Shaping rate has the following restrictions regarding the downstream-rate:
If the downstream-rate is less than the configured shaping-rate (as set in the CLI or using RADIUS attributes) then it is applied, subject to other restrictions. If the downstream-rate is greater than or equal to the configured shaping-rate, no changes are performed.
The downstream-rate cannot be less than a configured guaranteed-rate. If it is, the downstream-rate is set to the guaranteed-rate.
The downstream-rate cannot be less than a configured adjust-minimum-rate. If it is, the downstream-rate is set to the adjust-mimimum-rate.
The downstream-rate cannot be less than 1000 bps. If it is, the downstream-rate is set to 1000 bps.
The downstream-rate cannot be less than the sum of the transmit-rates of all queues.