APN remap tables allow an operator to override an APN specified by a user, or the APN selected during the normal APN selection procedure, as specified by 3GPP TS 23.060. This atypical level of control enables operators to deal with situations such as:
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An APN is provided in the Activation Request that does not match with any of the subscribed APNs either a different APN was entered or the APN could have been misspelled. In such situations, the SGSN would reject the Activation Request. It is possible to correct the APN, creating a valid name so that the Activation Request is not rejected.
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In some cases, an operator might want to force certain devices/users to use a specific APN. For example, all iPhone4 users may need to be directed to a specific APN. In such situations, the operator needs to be able to override the selected APN.
An APN remap table group is a set of APN-handling configurations that may be applicable to one or more subscribers. When a subscriber requests an APN that has been identified in a selected operator policy, the parameter values configured in the associated APN remap table will be applied. For example, an APN remap table allows configuration of the following:
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APN aliasing - maps incoming APN to a different APN based on partial string match (MME and SGSN) or matching charging characteristic (MME and SGSN).
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Wildcard APN - allows APN to be provided by the SGSN when wildcard subscription is present and the user has not requested an APN.
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Default APN - allows a configured default APN to be used when the requested APN cannot be used for example, the APN is not part of the HLR subscription. In 21.4 and later releases, the configuration to enable default APN on failure of DNS query is enhanced to support S4-SGSN. When wildcard APN is received in subscription, the DNS request is tried with the MS requested APN and on failure of DNS, it is retried with the APN value configured in the APN remap table.
APN remap tables are
configured with commands in the APN Remap Table configuration mode. A single
APN remap table can be associated with multiple operator policies, but an
operator policy can only be associated with a single APN remap table.
For planning purposes, based on the system configuration, type of packet processing cards, type of network (2G, 3G, 4G, LTE), and/or application configuration (single, combo, dual access), the following APN remap table configuration rules should be considered:
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1 - maximum number of APN remap tables that can be associated with an operator policy.
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1000 - maximum number of APN remap tables per system (such as an SGSN).
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100 - maximum remap entries per APN remap table.