Policing

The policer configuration uses inputs from the session manager, these inputs are received either from PCF as AMBR or from flow-level QoS information. The values received from the PCF are always accepted for session-level AMBR policing. However, the flow-level policing is prioritized, if available, and AMBR policing is applied sequentially. That is to say, the policer engine applies the hierarchical policing—first the flow-level/rule bandwidth limiting and then the session-level bandwidth limiting.

Note

AMBR modifications during session run-time through RAR or CCA-U is applicable.

The input values received from the session manager are pushed into a policer configuration and a policer token bucket. For each direction - uplink or downlink, a new record is created for Policer configuration and Policer token bucket.

The Policer configuration is the reference for the policer engine, and the policer token bucket is used for calculation and restoration of values.

Currently, Policing is supported for AMBR received from PCF and rule-level QoS information for dynamic rules. For static and predefined rules, bandwidth limiting is achieved by the bandwidth policy configuration. Extended bit rates configured in bandwidth-policy configuration in Active Charging Service Configuration mode on SMF is provided to the UPF by RCM, and same is applied for policing by the UPF. An example configuration of bandwidth policy, with extended bit rate, is given below:

configure
  active-charging service ACS
    bandwidth-policy BWP                                                                                                                                                    
      flow limit-for-bandwidth id 1 group-id 2                                                                                                            
      flow limit-for-bandwidth id 2 group-id 3 
      flow limit-for-bandwidth id 100 group-id 100                                                                                                                             
      group-id 2 direction uplink peak-data-rate 256000 peak-burst-size 1000 violate-action discard                                                                         
      group-id 3 direction downlink peak-data-rate 256000 peak-burst-size 1000 violate-action discard
      group-id 4 direction uplink peak-data-rate 300000 peak-burst-size 1200 violate-action lower-ip-precedence
      group-id 5 direction downlink peak-data-rate 300000 peak-burst-size 1200 violate-action lower-ip-precedence committed-data-rate 256000 committed-burst-size 1000 exceed-action lower-ip-precedence
      group-id 100 direction downlink peak-data-rate-kbps 4294967295 peak-burst-size 4294967295 violate-action discard
      group-id 100 direction uplink peak-data-rate-kbps 4294967295 peak-burst-size 4294967295 violate-action discard
      exit
    charging-action catchall
      flow limit-for-bandwidth id 1
      exit
    rulebase cisco
      bandwidth default-policy BWP
      exit
    end

Limitations

In this release, Policing has the following limitations:

  • Modification of bandwidth-policy isn't supported.

  • Interaction with other features, such as token replenishment (both APN-level and ACL-level) isn't supported.

  • Currently, policer-based statistics aren't supported. You can verify bandwidth limiting using network performance monitoring tools.