bearer activation the Gn/S4-SGSN sends the current Maximum APN Restriction
value for the UE to the GGSN/ P-GW in the Create PDP Context Request/ Create
Session Request (if it is the first activation for that UE or if the APN
Restriction is disabled, Maximum APN restriction will be "0" in the Create PDP
Context Request/ Create Session Request). The GGSN/P-GW has an APN restriction
value for each APN. If the Maximum APN Restriction for the subscriber is
received in the Create PDP Context Request/ Create Session Request and APN
Restriction value of the APN to which activation is being requested do not
concur then the GGSN/P-GW rejects the activation by sending a Create PDP
Context / Create Session Response failure message to the G/S4-SGSN with EGTP
cause "EGTP_CAUSE_INCOMPATIBLE_APN_REST_TYPE (0x68)".
If the Maximum APN
Restriction of the subscriber and APN Restriction of the APN to which
activation is ongoing agree as per APN Restriction rules, the GGSN/P-GW sends
the APN Restriction value of the APN in the Create PDP Context / Create Session
Response as success during activation. The Gn/S4-SGSN updates the APN
restriction value of that PDN connection with the value received from GGSN/P-GW
in the Create PDP Context/ Create Session Response. The APN restriction value
can be received by a new SGSN through context response and forward re-location
The combination of
APN Restriction values of all the PDN connections of a particular UE should be
valid and the maximum APN restriction value of the UE should be updated
whenever the APN restriction value of a PDN connection is updated.
Table below displays
the valid combinations of APN restriction values:
Table 1. APN restriction
Type of APN
Restriction Value allowed to be established
Contexts or Restriction
WAP or MMS
1, 2, 3
(for example MMS subscribers)
(for example non-MMS subscribers)
combination of APN restriction values is achieved in the Gn/ S4-SGSN based on
the APN restriction value of the most restrictive PDN connection. If the bearer
with the most restrictive APN restriction value gets de-activated, the maximum
APN restriction value is re-calculated from among the remaining active default
In the Create PDP
Context /Create Session Request during default bearer activation, the
Gn/S4-SGSN sends the Maximum APN Restriction Value for the UE. If no value is
available (if this default bearer is the first activation) then, the Maximum
APN restriction value will be "0" in Create Session Request. A value of "0" in
the Create PDP Context / Create Session Request for Maximum APN restriction
indicates there are no other existing PDN connections for the UE or APN
restriction is disabled.
If the APN
restriction value received in the Create PDP Context / Create Session Response
during activation violates the current Maximum APN restriction, then the SGSN
rejects the activation and also de-activates any other PDN connection to the
same APN. The SGSN considers the APN restriction received in latest Create PDP
Context / Create Session Response as the latest value of the APN restriction
associated with that APN. If there are any other PDN connections to this APN,
the SGSN updates the APN restriction associated with those PDN connections. If
the APN restriction value is not violated then the SGSN updates the APN
restriction value for that PDN connection and any other PDN connection to the
same APN with the value received in the Create PDP Context / Create Session
Response and re-calculates the Maximum APN restriction value for MS.
If APN restriction
is enabled, but the SGSN does not receive any APN restriction value in the
Create PDP Context / Create Session Response and if another PDN connection
exists to the same APN, the value of APN restriction is copied from that APN.
If no value is available, the APN restriction value is assumed to be "0".
If the current
Maximum APN restriction value for the UE is present and the SGSN receives a new
default bearer activation request to another APN, while the APN restriction
feature is enabled, the activation is rejected with the appropriate sm cause.
If the Gn/ S4-SGSN
receives a Create PDP Context/Create Session Response as failure from the P-GW
with EGTP cause "EGTP_CAUSE_INCOMPATIBLE_APN_REST_TYPE (0x68)", then the Gn/
S4-SGSN sends an activate reject to the MS with SM cause "(112) APN restriction
value incompatible with active PDP context". Any de-activate request sent to
the MS due to APN Restriction violation also has the same SM cause.
For every new
activation request, the SGSN re-calculates the Maximum APN Restriction from
among other currently active PDN connections (excluding those PDNs for which
any de-activation is ongoing.)
The APN restriction
values are recovered during session recovery. In old SGSN ISRAU, the APN
restriction associated with each PDN is sent to the peer in Context Response.
In old SGSN SRNS re-location, the APN restriction associated with each PDN
connection is sent to the peer in Forward Re-location Request.
In IRAT procedures,
the APN restriction for each PDN connection is transferred internally during
IRAT and these values are used for subsequent activations after IRAT.
In new SGSN ISRAU,
the APN restriction values received in context response are used in the
subsequent activations after ISRAU.
In new SGSN SRNS,
the APN restriction values received in the forward re-location are used in
subsequent activations after SRNS re-location.