APN AMBR Traffic Policing

Feature Summary and Revision History

Summary Data

Table 1. Summary Data

Applicable Product (s) or Functional Area

5G-UPF

Applicable Platforms

VPC-SI

Feature Default Setting

Disabled – Configuration Required

Related Changes in this Release

Not Applicable

Related Documentation

Not Applicable

Revision History

Table 2. Revision History
Revision Details Release
First introduced. 2021.01.0

Feature Description

The APN-AMBR is a subscription parameter that is stored per APN in the HSS. S-GW provides APN-AMBR during default bearer establishment procedure. APN-AMBR limits the aggregate bit rate that can be expected to be provided across all non-GBR bearers and across all PDN connections of the same APN. Each of those non-GBR bearers can potentially utilize the entire APN-AMBR, for example, when the other non-GBR bearers do not carry any traffic. The P-GW enforces the APN-AMBR in downlink and uplink direction.

Limitations

The token-replenishment-interval and violate-action shape CLI commands are not supported.

Configuring the APN AMBR Traffic Policing Feature

This section describes how to configure the APN-AMBR Traffic Policing feature.

configure 
           context  context_name 
             apn  apn_name 
         apn-ambr rate-limit direction { downlink | uplink } [ burst-size { auto-readjust duration { milliseconds msecs | seconds } | violate-action { drop | lower-ip-precedence | transmit } 
                   end

NOTES:

  • rate-limit direction { downlink | uplink } : Specifies that the rate limit is to be applied to either the downlink (network to subscriber) traffic or the uplink (subscriber to network) traffic.

  • burst-size { auto-readjust duration milliseconds msecs | seconds } : This parameter is used by policing algorithms to permit short bursts of traffic not to exceed the allowed data rates. It’s the maximum size of the token bucket.

    • auto-readjust duration seconds : The duration (in seconds) used in this burst size calculation: burst size = peak data rate/8 * auto-readjust duration.

      • Seconds must be an integer value from 1-30. Default is 1 second.

    • milliseconds : msecs must be an integer value from 100-900, in increments of 100 milliseconds. For example, 100, 200, or 300, and so on.

  • violate-action { drop | lower-ip-precedence | transmit } : The action that the P-GW takes when the data rate of the bearer context exceeds the AMBR.

    • drop : Drops violating packets.

    • lower-ip-precedence : Sets the DSCP value to zero ("best effort") for violating packets.

    • transmit : Transmits violating packets. This is the default behavior of the feature.

  • Prior to this feature, the default behavior was to drop the violating packets.

Monitoring and Troubleshooting

This section provides information about the commands available to monitor and/or troubleshoot the APN-AMBR Traffic Policing feature.

Show Commands and/or Outputs

This section provides information about the show commands available for monitoring and/or troubleshooting the APN-AMBR Traffic Policing feature.

  • show user-plane-service pdn-instance name <apn_name>

    Use this show command in UPF to see if the rate limit is enabled/disabled, burst size, and other such parameters for downlink/uplink traffic:

    • APN-AMBR

      • Downlink Apn Ambr: Indicates if the rate limit is enabled or disabled for downlink traffic.

        • Burst Size: Indicates the burst size of the downlink traffic.

        • Auto Readjust: Indicates if the auto-readjust is enabled or disabled for downlink burst size.

        • Auto Readjust Duration: Indicates the duration used in downlink burst size calculation.

        • Burst Size(bytes): Indicates the burst size in bytes.

        • Violate Action: Indicates the action that the P-GW takes when the data rate of the bearer context exceeds the AMBR for downlink traffic.

      • Uplink Apn Ambr: Indicates if the rate limit is enabled or disabled for uplink traffic.

        • Burst Size: Indicates the burst size of the uplink traffic.

        • Auto Readjust: Indicates if the auto-readjust is enabled or disabled for uplink burst size.

        • Auto Readjust Duration: Indicates the duration used in uplink burst size calculation.

        • Burst Size(bytes): Indicates the burst size in bytes.

        • Violate Action: Indicates the action that the P-GW takes when the data rate of the bearer context exceeds the AMBR for uplink traffic.

      • Token Replenishment Interval: Indicates the token replenishment interval duration.

  • show sub user-plane-only full all

    Use this show command in UPF to see the count of packets that are dropped, and IP precedence lowered due to APN-AMBR policer. The following fields are introduced in support of this feature:

    • APN AMBR Uplink Pkts Drop: Indicates the number of APN-AMBR packets that are dropped for uplink traffic.

    • APN AMBR Uplink Bytes Drop: Indicates the number of APN-AMBR bytes that are dropped for uplink traffic.

    • APN AMBR Uplink Pkts IP pref lowered: Indicates the number of APN-AMBR uplink packets for which IP precedence is lowered.

    • APN AMBR Uplink Bytes IP pref lowered: Indicates the number of APN-AMBR uplink bytes for which IP precedence is lowered.

    • APN AMBR Downlink Pkts Drop: Indicates the number of APN-AMBR packets that are dropped for downlink traffic.

    • APN AMBR Downlink Bytes Drop: Indicates the number of APN-AMBR bytes that are dropped for downlink traffic.

    • APN AMBR Downlink Pkts IP pref lowered: Indicates the number of APN-AMBR downlink packets for which IP precedence is lowered.

    • APN AMBR Downlink Bytes IP pref lowered: Indicates the number of APN-AMBR downlink bytes for which IP precedence is lowered.