Encoding Destination-Host AVP in Redirected Requests

This chapter provides the implementation details to include the Destination-Host AVP in Diameter Redirected requested messages on S6b, SWm and STa interfaces.

This chapter discusses the following topics for this feature:

Feature Description


Note

This feature is applicable to 18.4.3 and later releases.

When an application receives the Result-Code 3006 -DIAMETER_REDIRECT_INDICATION from the AAA server, the Diameter request message is forwarded to the Redirect-Host specified in the server's response. The message gets routed properly in case the Diameter host is directly connected to the AAA server. If there is a DRA between P-GW/ePDG and AAA server, the message goes into a loop as DRA always routes the packet to the AAA server which had redirected the message. To overcome this problem, the Destination-Host AVP should be included in the redirected messages. This functionality is supported by extending the existing CLI command "destination-host-avp " to include "redirected-request " as an optional configuration.

This option "redirected-request " encodes Destination-Host AVP in any type of Diameter redirected messages. Since any redirected request is considered as retried request, if the option "retried-request " is used, by default Update (Interims) or Terminate (Stop) redirected-request will be encoded with Destination-Host AVP without the "redirected-request " option being configured. The reason to configure "redirected-request " as part of "retried-request " option is, in case of Initial-Retried request the Destination-Host AVP is not encoded if "retried-request " option alone is configured. To enable encoding Destination-Host AVP for Initial-Retried request, "redirected-request " is supported as an extension to "retried-request " as well.

In releases prior to 18, the Destination-Host AVP was encoded in the redirected message only if the original request included Destination-Host AVP. In release 18 and beyond, the encoding of Destination-Host AVP in redirected message is based on the new configurable option redirected-request in "destination-host-avp " CLI command. If the CLI command is enabled, Destination-Host AVP will be included in any type of Diameter redirected messages.

Limitations

As per the current implementation, it is not possible to send retried messages to a different host using the same peer. This behavior is applicable for normal retry and failure-handling scenarios.

Standards Compliance

This feature is implemented to be compliant with 3GPP TS 29.273 specification.

Configuring Destination-Host AVP in Redirected Request

This section provides information on the commands used to include the Destination-Host AVP in the redirected request messages.

Encoding Destination-Host AVP in Redirected Requests

Use the following configuration commands to include the Destination-Host AVP in the redirected request messages on ePDG, P-GW and SaMOG sent over the respective authentication interfaces (SWm, S6b and STa). 

configure  
    context  context_name 
         diameter endpoint  endpoint_name 
              destination-host-avp { always | initial-request [ redirected-request ] | retried-request [ redirected-request ] | session-binding [ redirected-request ] }  
              default destination-host-avp  
              end

Notes:

  • redirected-request : Encodes the Destination-Host AVP in any redirected request message.
  • always : Encodes the Destination-Host AVP in all types of request messages.
  • initial-request : Encodes the Destination-Host AVP in initial request but not in retried request.
  • retried-request : Encodes the Destination-Host AVP in retried request but not in initial request.
  • session-binding : Encodes the Destination-Host AVP after the Diameter session is bound with a host.