SMF Overload Protection

Feature Summary and Revision History

Summary Data

Table 1. Summary Data

Applicable Products or Functional Area

SMF

Applicable Platform(s)

SMI

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.

2020.03.0

Feature Description

An interface can handle only a specified number of incoming requests. When the incoming requests exceed the specified numbers, the interface overloads. For instance, an interface is overloaded when:

  • There is a network element failure causing large number of re-attaches

  • Multiple users perform location update or transition from idle to active mode frequently

Overloading causes the interface to either drop the requests or delay processing the request. The overall network performance degrades because of overloading at the interface. This can lead to node congestion, failure or collapse which in turn causes load increase on the other nodes.

The SMF measures different resources and defines the load based on those measurements. Also, the SMF updates the NRF about the load. Currently, the SMF applies overload protection on inbound messages. The external nodes throttle towards the SMF to come out of a congestion when overload protection is applied on the inbound interface (SBA Interface).

NOTE: The scope of this feature is only on overload due to inbound requests on SBA interface.

How it Works

The SMF protects inbound requests from overloading at Endpoint and Application levels.

  • Endpoint Level – The protection is based on the HTTP request method without taking the message type into account.

  • Application Level – The protection is based on the message type.

Overload Protection at Endpoint

For endpoints, the SMF offers overload protection at both the endpoint and client levels. The SMF defines the overload threshold limits for the inbound request messages. Based on the threshold range, the SMF can reject the inbound request messages. The SMF sends back an HTTP response with the configured status to the request initiator.

The following are the overload threshold limits defined in the SMF:

  • Low – When this threshold is met, only the POST method (with generic URI contributing to resource allocation) is rejected.

  • High – All messages are rejected with the configured (reject) statuses when this threshold is met.

  • Critical – All messages are rejected with the configured (reject) statuses when this threshold is met.

Configuring Overload Protection

This section describes the configuration procedures involved in configuring the overload protection for inbound request messages.

Configuring Overload Protection at Endpoint Level

Use the following configuration to configure overload protection at endpoint level.


configure 
   endpoint sbi 
      overload-control threshold threshold_limit threshold_range action action_status action_code range 
      commit 
      end

NOTES:

  • overload-control – Specify the overload control at endpoint level.

  • threshold – Specify the threshold limit and range.

  • threshold_limit –Specify the threshold limit. threshold_limit must be one of the following:

    • low – Specify the low threshold limit for overload protection.

    • high – Specify the high threshold limit for overload protection.

    • critical – Specify the critical threshold limit for overload protection.

  • thershold_range – Specify the threshold range. threshold_range must be an integer in the range of 10 – 100000.

  • action – Specify the action to be taken for the threshold limit.

  • action_status – Specify the action for the threshold limit. action_status must be:

    • reject – Rejects the inbound messages if the specified threshold range is met.

  • action_code – Specify the action status code. action_code must be:

    • reject-code – Specify the reject status code.

  • range – Specify the range of the action code. range must be an integer in the range of 100 – 600.

The following is an example configuration:


overload-control threshold low 500 action reject reject-code 501 
overload-control threshold critical 10000 action reject reject-code 329

Configuring Overload Protection at Client Level

Use the following configuration to configure overload protection at client level.


configure 
   endpoint sbi 
      overload-control client threshold threshold_limit threshold_range action action_status action_code range 
      commit 
      end

NOTES:

  • overload-control client – Specify the overload control at client level.

  • threshold – Specify the threshold limit and range.

  • threshold_limit –Specify the threshold limit. threshold_limit must be one of the following:

    • low – Specify the low threshold limit for overload protection.

    • high – Specify the high threshold limit for overload protection.

    • critical – Specify the critical threshold limit for overload protection.

  • thershold_range – Specify the threshold range. thershold_range must be an integer in the range of 10 – 100000.

  • action – Specify the action to be taken for the threshold limit.

  • action_status – Specify the action for the threshold limit. action_status must be:

    • reject – Rejects the inbound messages if the specified threshold range is met.

  • action_code – Specify the action status code. action_code must be:

    • reject-code – Specify the reject status code.

  • range – Specify the range of the action code. range must be an integer in the range of 100 – 600.

The following is an example configuration:


overload-control client threshold low 50 action reject reject-code 329 
overload-control client threshold critical 20000 action reject reject-code 501

Verifying the Overload Protection Configuration

Use the show running-config command to view the overload protection configuration in the SMF Ops Center. The following is a sample output of the show running-config command. 


[cluster1/data] example# show running-config 
endpoint sbi 
 overload-control threshold low 5000 action reject reject-code 555 
 overload-control threshold high 7000 action reject reject-code 329 
 overload-control threshold critical 10000 action reject reject-code 503 
 overload-control client threshold low 750 action reject reject-code 329 
 overload-control client threshold high 500 action reject reject-code 329 
 overload-control client threshold critical 1000 action reject reject-code 503 
 interface n11 
  overload-control threshold low 4000 action reject reject-code 555 
  overload-control threshold high 6000 action reject reject-code 329 
  overload-control threshold critical 7000 action reject reject-code 503 
  overload-control client threshold low 500 action reject reject-code 329 
  overload-control client threshold high 700 action reject reject-code 329 
  overload-control client threshold critical 800 action reject reject-code 503 
 exit

Monitoring and Troubleshooting

This section provides information regarding bulk statistics available to monitor and troubleshoot this feature.

Statistics

The following statistics are available in support of Overload Control.

Bulk Statistics Statistics Type Description
endpoint_overload_status Gauge Contains Endpoint-Name, Interface-Name and Overload-Level as labels. Once any level(low/high/critical) is hit, the gauge value will be set to 1. In normal condition the value is set to 0.
endpoint_client_overload_status Gauge Contains Endpoint-Name, Interface-Name, peer-host name and Overload-Level as labels. Once any level(low/high/critical) is hit, the gauge value will be set to 1. In normal condition the value is set to 0.
endpoint_pending_request Gauge Display current outstanding request for an endpoint. It contains Endpoint name and Interface Name as label.
endpoint_client_pending_request Gauge Display current outstanding request for a peer connected with an endpoint. It contains Endpoint name, Interface Name and peer host address connected to the endpoint as label.