QoS Policies

QoS policies define per-subscriber rate limiting using VPP's native policer engine. Each policy is a named template that gets instantiated as an independent policer per subscriber at session activation, giving each subscriber its own token bucket state.

Policies are defined under the top-level qos-policies key and referenced by name from service groups.

Policy Settings

Field	Type	Description	Default
`cir`	uint32	Committed information rate (kbps)	required
`eir`	uint32	Excess information rate (kbps)	equal to `cir`
`cbs`	uint64	Committed burst size (bytes)	`cir * 1000 / 8`
`ebs`	uint64	Excess burst size (bytes)	equal to `cbs`
`conform`	Action	Action for conforming traffic	required
`exceed`	Action	Action for exceeding traffic	required
`violate`	Action	Action for violating traffic	required

All rates are in kilobits per second. For example, cir: 100000 = 100 Mbps.

The policer uses the 2-rate 3-colour (2R3C) model defined in RFC 2698. Traffic is classified into one of three colours based on instantaneous rate against the CIR and EIR token buckets, and the configured action is applied.

Actions

Each action block specifies what to do with traffic in that colour class.

Field	Type	Description	Example
`action`	string	`transmit`, `drop`, or `mark-and-transmit`	`transmit`
`dscp`	uint8	DSCP value to mark (only used with `mark-and-transmit`)	`46`

Usage

QoS policies are applied to subscribers through service groups. A service group references policy names for ingress (upload) and egress (download) directions independently.

qos-policies:
  100m-policer:
    cir: 100000
    conform:
      action: transmit
    exceed:
      action: drop
    violate:
      action: drop

service-groups:
  residential:
    qos:
      ingress-policy: 100m-policer
      egress-policy: 100m-policer

When a subscriber session activates, the referenced policies are instantiated as VPP policers and attached to the subscriber's sub-interface. When the session is released, the policers are detached and deleted.

Asymmetric Rates

Use different policies for upload and download to create asymmetric speed profiles.

qos-policies:
  upload-50m:
    cir: 50000
    conform:
      action: transmit
    exceed:
      action: drop
    violate:
      action: drop

  download-200m:
    cir: 200000
    conform:
      action: transmit
    exceed:
      action: drop
    violate:
      action: drop

service-groups:
  residential:
    qos:
      ingress-policy: upload-50m
      egress-policy: download-200m

DSCP Marking

Use mark-and-transmit to remark excess traffic instead of dropping it.

qos-policies:
  business-with-remarking:
    cir: 100000
    eir: 200000
    conform:
      action: transmit
    exceed:
      action: mark-and-transmit
      dscp: 0
    violate:
      action: drop

In this example, traffic up to 100 Mbps is forwarded unchanged, traffic between 100-200 Mbps is remarked to DSCP 0 (best effort), and traffic above 200 Mbps is dropped.

AAA Override

AAA can override QoS policy names per subscriber by returning qos.ingress-policy and qos.egress-policy attributes. See service groups for the full list of overridable attributes.