is applicable to 18.4.3 and later releases.
ePDG, P-GW and SaMOG
connects with the AAA server over SWm, S6b and STa Diameter interfaces
respectively. When a subscriber PDN connects, the PDN is authenticated over
these authentication interfaces. P-GW sends AAR whereas ePDG/SaMOG sends DER to
authorize the subscriber. ePDG/P-GW/SaMOG has the capability to select one of
the available AAA servers based on priority or round robin method.
ePDG/P-GW/SaMOG sends DER/AAR to the selected AAA server. If the HSS indicates
that the subscriber is currently being served by a different AAA server, it
sends the DIAMETER_REDIRECT_INDICATION Result-Code (3006) over SWm/S6b/STa
interfaces requesting ePDG/P-GW/SaMOG to redirect the AAR/DER request to the
already bound AAA server.
If the redirection
of DER/AAR fails for some reason (Diameter TCP connection being down or
Diameter Response-Timeout), the ePDG/P-GW/SaMOG redirects this message to any
other available AAA server with the AAA-Failure-Indication AVP set to 1. AAA
server forwards the AAA-Failure-Indication AVP to HSS, which will reset the
initial binding of the PDN with the failed AAA and bind the PDN with the AAA
server that forwarded the AAA-Failure-Indication AVP.
authentication at ePDG/P-GW/SaMOG, the ePDG/P-GW/SaMOG disconnects any other
previously connected PDN for the same subscriber. This is done so that the PDNs
are reestablished and are bound to the new AAA server.
In order to support
a geo-redundant architecture for VoWiFi service, ePDG/P-GW/SaMOG supports the
AAA-Failure-Indication AVP as described in 3GPP TS 29.273 specification. This
AVP value is set to 1 to indicate that a previously assigned AAA Server is
In support of this
feature, a new bulk statistics field is added to the output of
aaa-statistics command to track the number of times the
AAA-Failure-Indication AVP is sent over these authentication interfaces.