The UE Overload Protection feature provides a mechanism to monitor resource utilization of system bandwidth, channel drop rate, SM CPU, SM memory and VPP CPU. When resources exceed configured threshold, certain identified UEs shall be impacted. For example, when system bandwidth resource, which is global, exceeds the configured threshold, the UEs across the system enabled for this feature shall be impacted. Remaining resources are considered as local to CPU complex.

Currently, P-GW supports managing or throttling of traffics and includes the following functions as part of the UE Overload protection functionality:

• Identification of subscriber impact to a P-GW

• Setting thresholds or conditions on the impact of subscriber to a P-GW

• Sending responses to these thresholds by throttling one or more subscribers who exceeded the threshold.

The UE Overload protection feature works only with VPP-enabled ASR 5500 with DPC2 card and other platforms. Threshold handling is applicable only for DPC2 cards (maximum of 6DPC2 cards) that does not include any Demux card. Now you can configure this feature through CLI globally: The following functions are supported:

• Configuration of UE Overload control profiles.

• Managed through PCRF– Enables or disables ue overload protection feature for each subscriber and based on the AVP received during the session establishment.

• Allows you to specify configuration actions when thresholds are met. You can adjust the APN-AMBR-DL and APN-AMBR-UL temporarily until the overload condition persists. UE Overload APN AMBR UL/DL values applied to the UEs are reverted to their original values in case of Session Manager restarts, Card migration, and ICSR.

  Note	If an UE session is under throttling, then APN-AMBR values get modified immediately if the new APN_AMBR values are lesser than the currently applied values. Otherwise, the values are not programmed in the fast path, instead, it gets applied once the threshold is relaxed.

• Allows you to receive periodic load condition (including VPP load) from Resource manager and provision to set up overload condition in Session Manager.

• show status: To optimize the system load the show status command is organized to show the recent status for up to 18 records and along with system-wide criteria. When the system criteria is met as a lower priority criteria, complex wide higher priority can still override for every complex level based on the complex level threshold crossing. You can view the following results through show status :

  • All "met" parameters, when a CPU complex is in throttled state due to one threshold parameter and if other threshold parameters meet on that same CPU complex.

    All threshold parameters, if multiple threshold parameters are met within a given configured criteria.

    The system bandwidth threshold, if met, is displayed as a separate row (last row) in the show status . The Activation Time for system bandwidth can be any one of the CPU complex activation times.

In StarOS, all sessions are distributed across multiple Session Managers. Demux Manager acts as a central element of resource utilization collection at the CPU complex level. When the network traffic speed increases in conjunction with the deployment of 5G, P-GW allows subscribers to manage the performance of the network, such as high-speed downloads, User Equipment (UE) overload detection or recovery scenarios with the help of Demux Manager.

The UE Overload protection feature works on a detection algorithm, which is designed to work and targeted for the DPC2 card-based architecture. However, this algorithm works across different line cards. Following table explains the Overload detection algorithm steps.

The limitations are:

• Works only with VPP-enabled ASR 5500 whereby the load monitoring is performed on the DPC2 card.

• As the intent of this feature is to bring down the system load by throttling the user traffic through AMBR parameters, the operator should take care of enabling the sessions to be throttled.

• The operator must enter the actual name of the APNs at the time of entering the APN names in the list. This is because there is no validation on this list with respect to the APN names used in the system. For APN name, which is not available in the system, the error is not displayed during configuration.You can view the error through the show config errors command.

UE Overload feature is applicable only to the new UE sessions that come up after the UE Overload configuration. When you enable the UE Overload configuration for a valid virtual APN(s) or base APN(s), you cannot modify any existing UE sessions to apply the feature.

Use the following commands to configure the ue- overload control profile settings on ASR5500:

configure 
    context context_name 
      ue-overload-control-profile name 
         end   

Notes:

• ue-overload-control-profile : Creates a new UE Overload Control Profile without prompting for confirmation.

  Note	Deletion of an UE Overload profile or an applied/active criteria or applied/active action profile or parameters results in relaxing of applied threshold(s) on a Card/CPU complex immediately. Any modification of configuration takes effect only in the next check-interval .

Use the following commands to configure ue-overload criteria.

configure 
   context context_name 
      ue-overload-control-profile overload-criteria  value prioritypriority_value  
         system 
             bandwidth-thresholdvalue 
             drop-rate-thresholdvalue 
        exit 
         sessmgr 
             cpu-thresholdvalue 
             memory-thresholdvalue 
         exit 
         vpp 
             cpu-thresholdvalue 
         exit 
         overload action name 
         exit 
         apn name 
             overload-actionname 
             downlink-ambrvalue 
             uplink-ambrvalue 
         check-intervalseconds 
         dampen-intervalseconds 
        exit 

Notes:

• overload-criteria : Configures Overload criteria thresholds for system, sessmgr, vpp parameters along with criteria priority.

  overload-action : Configures overload action associated with this overload criteria.

• sessmgr : Configures Session Manager threshold for various overload criteria parameters.

• system : Configures System threshold for various overload criteria parameters.

• vpp: Configures VPP threshold for various overload criteria parameters.

• apn : Includes APN names to apply for this UE Overload control profile. APN is added in the UE Overload configuration in the following two ways:

  • enable-by-default – UE Overload feature is applicable to the UE sessions if the UEOVERLOAD field is enabled in the Service-Feature AVP or if UEOVERLOAD field or Service-Feature AVP is altogether missing.

  • enable-by-gx – UE Overload feature is applicable to the UE sessions only if the UEOVERLOAD field is enabled in the Service-Feature AVP.

  check-interval : Configures UE Overload parameters monitoring interval (in seconds). The default value is 30 seconds.

• dampen-interval : Configures minimum time defined for the system to be in the Overloaded State or Normal State (in seconds). The default value is 300 seconds.

• default : Restores default value assigned for following options.

  • do : Spawns an exec mode command which displays information to the administrator.

  • end : Exits configuration mode and returns to Exec Mode.

  • exit : Exits current configuration mode, returns to previous mode.

  • no : Enables or disables the following option:

    • overload-criteria : Configures Overload criteria thresholds for system, session manager, and VPP parameters along with criteria priority.