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5G NR-RRC and DLT_USER

asked 2022-07-28 03:44:06 +0000

JeffB gravatar image

Hi All,

I have byte codes for 5G RRC Signalling messages in Hex format.

I am trying to import as Hex, then use DLT_USER to decode them, however I get an error when I try to enter nr-rrc as the protocol, saying "dissector not found" - I have tried multiple permutations & combinations.

I'm using v3.6.7.

Any suggestions?

Thanks in advance.

Jeff

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answered 2022-07-28 18:55:56 +0000

Chuckc gravatar image

(posting this as answer but there's got to be a better way)

The User DLTs Table says "protocol" but it really wants a dissector name.
You can get a list of the current dissectors with Lua.

1. Open the Lua console in the Wireshark Gui - Tools->Lua->Console
2. Open the Lua "REPL" - Tools->Lua->Evaluate, copy in the code below and click Evaluate.

for k,v in pairs(Dissector.list()) do
  print(k,v)
end

The "nr-rrc" entries I get for 3.6.7:

7/28/2022 1:44:30 PM 1021   nr-rrc.bcch.bch
7/28/2022 1:44:30 PM 1022   nr-rrc.bcch.dl.sch
7/28/2022 1:44:30 PM 1023   nr-rrc.cg_configinfo
7/28/2022 1:44:30 PM 1024   nr-rrc.dl.ccch
7/28/2022 1:44:30 PM 1025   nr-rrc.dl.dcch
7/28/2022 1:44:30 PM 1026   nr-rrc.pcch
7/28/2022 1:44:30 PM 1027   nr-rrc.radiobearerconfig
7/28/2022 1:44:30 PM 1028   nr-rrc.rrc_reconf
7/28/2022 1:44:30 PM 1029   nr-rrc.rrc_reconf_msg
7/28/2022 1:44:30 PM 1030   nr-rrc.sbcch.sl.bch
7/28/2022 1:44:30 PM 1031   nr-rrc.scch
7/28/2022 1:44:30 PM 1032   nr-rrc.ue_capabilityrat_containerlist
7/28/2022 1:44:30 PM 1033   nr-rrc.ue_mrdc_cap
7/28/2022 1:44:30 PM 1034   nr-rrc.ue_mrdc_cap_msg
7/28/2022 1:44:30 PM 1035   nr-rrc.ue_nr_cap
7/28/2022 1:44:30 PM 1036   nr-rrc.ue_nr_cap_msg
7/28/2022 1:44:30 PM 1037   nr-rrc.ue_radio_access_cap_info
7/28/2022 1:44:30 PM 1038   nr-rrc.ue_radio_paging_info
7/28/2022 1:44:30 PM 1039   nr-rrc.ul.ccch
7/28/2022 1:44:30 PM 1040   nr-rrc.ul.ccch1
7/28/2022 1:44:30 PM 1041   nr-rrc.ul.dcch
7/28/2022 1:44:30 PM 1042   nr-rrc.ul.dcch_msg_msg
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Comments

Thanks for your reply Chuck - it's most helpful and I got some messages decoded this way.

Yes agree with your "There's got to be a better way" - this means that I either need to a) have each message in a separate trace since the DLT_USER decode doesn't do the entire RRC protocol suite, rather I need to do it per message, or b) Set a different DLT_USER value for each RRC message type.

I'll play around with trying to add some dummy MAC layer headers to the data and see if I can get Wireshark to decode.

JeffB gravatar imageJeffB ( 2022-07-29 03:22:24 +0000 )edit

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Asked: 2022-07-28 03:44:06 +0000

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Last updated: Jul 28