5GMM Status

5GMM Status is a simple error reporting message. Either the UE or the AMF can send it when a 5GMM protocol error is detected and a specific procedure-specific reject message is not the right response. The important field is the 5GMM cause, which tells the peer why the status message was sent.

• Signaling Sequence
• Message Structure
  • Example : 5GMM Status

Signaling Sequence

There is no multi-step procedure in the normal sense. The status message is sent as an error indication after one side detects a problem in a received 5GMM message.

Message Structure

The 5GMM Status message contains the standard 5GMM header and the 5GMM cause IE. The cause value is the key diagnostic information. In trace analysis, this message usually means that the previous NAS message or the current NAS state should be checked carefully.

Example : 5GMM Status

The Amarisoft MME logs checked for this update did not contain a decoded 5GMM Status instance, so the following is a constructed decoding example for a malformed message case. The whole message is shown below.

[NAS] UL 5GMM: 5GMM status
        Protocol discriminator = 0x7e (5GS Mobility Management)
        Security header = 0x2 (Integrity protected and ciphered)
        Auth code = example
        Sequence number = example
        Protocol discriminator = 0x7e (5GS Mobility Management)
        Security header = 0x0 (Plain 5GS NAS message, not security protected)
        Message type = 0x64 (5GMM status)
        5GMM cause = 0x60 (Invalid mandatory information)