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[RLC-LTE] Sequence analysis problem?

asked 2024-05-23 18:55:41 +0000

DrMom gravatar image

updated 2024-05-24 06:33:28 +0000

Hi, Could you please help to get the root cause of the following issue: UE has successfully finished the attach procedure. After some time UE goes to IDLE state, we can see RRCConnectionRelease in DL_DCCH. PCAP is OK. After Paging message, UE goes to CONNECTED state:

  1. RRCConnectioRequest in UL_CCCH
  2. RRCConnectionSetup in DL_CCCH

But starting from RRCConnectionSetupComplete all LTE RRC DL/UL_DCCH/NAS-EPS packets has rlc-lte.sequence-analysis.ok = False in RLC-LTE.

UE sends first packet with sn=0 for the new SRB (but it seems wireshark can't detect it), so expectedSequenceNumber != sequenceNumber. Does it work as expected?


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answered 2024-05-24 09:14:35 +0000

MartinM gravatar image

The problem is that the entries for that UE in sequence_analysis_channel_hash are not reset. This could be done in response to RRCConnectionRelease, but might be easier to do when the UE is being added back. If you are able to share a minimal capture file, I can try to fix it up.

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Thanks for your answer. Will the fix be included to a new version of wireshark for Windows and tshark for Linux? Is it possible to send pcap via direct message or e-mail?

DrMom gravatar imageDrMom ( 2024-05-27 10:52:36 +0000 )edit

If/when fixed, it would be available in wireshark/tshark for all platforms. For sending the pcap, I don't really want to add my email address here - maybe best idea is to join Discord server and message me (Martin Mathieson) there?

MartinM gravatar imageMartinM ( 2024-05-28 13:49:15 +0000 )edit

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Asked: 2024-05-23 18:55:41 +0000

Seen: 164 times

Last updated: May 24