F1SetUpRequest is not decoded completely

asked 2022-01-11 15:07:08 +0000

I am using wirershark version 3.7.0 and I see that the F1SetUpRequest is unable to decode the complete message. The F1SetUpRequest is shown as a malformed packed. The SIB1 in gNB-DU-System-Information is flagged as malformed packet. The decoding of the same hex dump using MARBEN online decoder is fine.

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There is a pcap attached to 16384 - rrc container not decoded in F1AP that shows the same behavior. Follow along there to see if it is the dissector or the capture file that needs to be corrected.

Chuckc gravatar imageChuckc ( 2022-01-11 17:14:31 +0000 )edit

So does the SIB1 container contains a SIB1 message and not a BCCH-DL-SCH message, as suggested by 3GPP 38.473? Could you share a pcap?

Pascal Quantin gravatar imagePascal Quantin ( 2022-01-11 17:29:14 +0000 )edit

When I try decoding only the the SIB1 message in the gNB-DU System Information, the message contains a BCCH-DL-SCH-Message. However in wireshark, I can see MIB and SIB1 decoded partially. The MIB is also a BCCH-BCH-Message. I am unable to share a capture at this time.

Sujitha Raj gravatar imageSujitha Raj ( 2022-01-14 19:30:38 +0000 )edit

Could you clarify why your system put a BCCH DL-SCH message for the SIB1? This does not seem to match the SIB1 definition found in 3GPP 38.473:

SIB1 message: OCTET STRING. SIB1 message, as defined in subclause 6.2.2 in TS 38.331 [8].

And 6.2.2 is the SIB1, not the BCCH-DL-SCH message that is defined in 6.2.1.

So your encoding does not match 38.473 specification. Same thing for the MIB: it should be the MIB message, not the BCCH-BCH message.

Pascal Quantin gravatar imagePascal Quantin ( 2022-01-18 15:32:24 +0000 )edit

This is day1 behavior. Hence, I am not sure why SIB1 is encoded as as BCCH-DL-SCH message in F1 message.

Sujitha Raj gravatar imageSujitha Raj ( 2022-01-18 16:00:01 +0000 )edit