8 Handling of unknown, unforeseen, and erroneous PMFP data

24.1933GPPAccess Traffic Steering, Switching and SplittingRelease 17Stage 3TS

8.1 General

The procedures specified in the clause apply to those messages which pass the checks described in this clause.

This clause also specifies procedures for the handling of unknown, unforeseen, and erroneous PMFP data by the receiving entity. These procedures are called "error handling procedures", but in addition to providing recovery mechanisms for error situations they define a compatibility mechanism for future extensions of the PMFP.

Clauses 8.1 to 8.8 shall be applied in order of precedence.

Detailed error handling procedures in the network are implementation dependent and may vary from PLMN to PLMN. However, when extensions of PMFP are developed, networks are assumed to have the error handling which is indicated in this clause as mandatory ("shall") and that is indicated as strongly recommended ("should").

Also, the error handling of the network is only considered as mandatory or strongly recommended when certain thresholds for errors are not reached during a dedicated connection.

For definition of semantical and syntactical errors see 3GPP TS 24.007 [13], clause 11.4.2.

8.2 Message too short or too long

8.2.1 Message too short

When a message is received that is too short to contain a complete message type information element, that message shall be ignored, c.f. 3GPP TS 24.007 [13].

8.2.2 Message too long

The maximum size of a PMFP message is 65535 octets.

8.3 Unknown or unforeseen extended procedure transaction identity (EPTI)

8.3.1 Extended procedure transaction identity (EPTI)

The following network procedures shall apply for handling an unknown, erroneous, or unforeseen EPTI received in a PMFP message:

a) In case the network receives a PMFP ECHO RESPONSE message in which the EPTI value does not match any EPTI in use, the network shall ignore the PMFP message.

The following UE procedures shall apply for handling an unknown, erroneous, or unforeseen EPTI received in a PMFP message:

a) In case the UE receives a PMFP ECHO RESPONSE message or a PMFP ACKNOWLEDGEMENT message in which the EPTI value does not match any EPTI in use, the UE shall ignore the PMFP message.

8.4 Unknown or unforeseen message type

If the UE or the network receives a PMFP message with message type not defined for the PMFP or not implemented by the receiver, it shall ignore the PMFP message.

NOTE: A message type not defined for the PMFP in the given direction is regarded by the receiver as a message type not defined for the PMFP, see 3GPP TS 24.007 [13].

If the UE receives a message not compatible with the PMFP state, the UE shall ignore the PMFP message.

If the network receives a message not compatible with the PMFP state, the network actions are implementation dependent.

8.5 Non-semantical mandatory information element errors

8.5.1 Common procedures

When on receipt of a message,

a) an "imperative message part" error; or

b) a "missing mandatory IE" error;

is diagnosed or when a message containing:

a) a syntactically incorrect mandatory IE;

b) an IE unknown in the message, but encoded as "comprehension required" (see 3GPP TS 24.007 [13]); or

c) an out of sequence IE encoded as "comprehension required" (see 3GPP TS 24.007 [13]) is received;

the UE shall ignore the PMFP message and the network shall:

a) try to treat the message (the exact further actions are implementation dependent); or

b) ignore the message.

8.6 Unknown and unforeseen IEs in the non-imperative message part

8.6.1 IEIs unknown in the message

The UE shall ignore all IEs unknown in a message which are not encoded as "comprehension required" (see 3GPP TS 24.007 [13]).

The network shall take the same approach.

8.6.2 Out of sequence IEs

The UE shall ignore all out of sequence IEs in a message which are not encoded as "comprehension required" (see 3GPP TS 24.007 [13]).

The network should take the same approach.

8.6.3 Repeated IEs

If an information element with format T, TV, TLV, or TLV-E is repeated in a message in which repetition of the information element is not specified in clause 6.2.1, the UE shall handle only the contents of the information element appearing first and shall ignore all subsequent repetitions of the information element. When repetition of information elements is specified, the UE shall handle only the contents of specified repeated information elements. If the limit on repetition of information elements is exceeded, the UE shall handle the contents of information elements appearing first up to the limit of repetitions and shall ignore all subsequent repetitions of the information element.

The network should follow the same procedures.

8.7 Non-imperative message part errors

8.7.1 General

This category includes:

a) syntactically incorrect optional IEs; and

b) conditional IE errors.

8.7.2 Syntactically incorrect optional IEs

The UE shall treat all optional IEs that are syntactically incorrect in a message as not present in the message.

The network shall take the same approach.

8.7.3 Conditional IE errors

NOTE: In this release of specification, there are no conditional IEs.

When upon receipt of a PMFP message the UE diagnoses a "missing conditional IE" error or an "unexpected conditional IE" error, or when it receives a PMFP message containing at least one syntactically incorrect conditional IE, the UE shall ignore the message.

When the network receives a message and diagnoses a "missing conditional IE" error or an "unexpected conditional IE" error or when it receives a message containing at least one syntactically incorrect conditional IE, the network shall either:

a) try to treat the message (the exact further actions are implementation dependent); or

b) ignore the message.

8.8 Messages with semantically incorrect contents

When a message with semantically incorrect contents is received, the UE shall perform the foreseen reactions of the procedural part of clause 5.4. If, however no such reactions are specified, the UE shall ignore the message.

The network should follow the same procedure.

Annex A (informative):
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