Malformed Packets when capturing OFH PCAP

[ujjwalpawar]

Hello All
I am trying to capture pcap of OFH packet. I know dumpcap is not supported, so I am running in socket interface mode and not DPDK.
But in wireshark i see malformed packets. I tried different bandwidth and different MIMO configuration but all U-plane packet are malformed both in DL and UL. C-Plane packets are fine.

These are wireshark settings

[AlaiaL]

Hi ujjwalpawar,

Some questions to get a little bit of context:

• Are you trying to capture DU or RU OFH traffic?
• Can you shared the configuration file of the gNB for this PCAP?
• Also, in case that it is RU OFH, can you share RU config?

I think it is a configuration problem, but with more context I can check it. Some key points though for U-Plane and wireshark:

• Make sure the compression type and compression bitwidth matches with the one configured in the gNB.
• Make sure that the compression header present flag matches the one configured in the gNB.
• MIMO configuration should NOT affect, as each port is sent in different packets (different eAxC)
• IIRC bandwidth is NOT a problem if you have configured the maximum number of PRs in wireshark (it seems good, I see 273)

Regarding the configuration, these are the parameters you need to make sure that wireshark and gNB config matches:

  compr_method_ul: bfp
  compr_bitwidth_ul: 9
  compr_method_dl: bfp
  compr_bitwidth_dl: 9
  compr_method_prach: bfp
  compr_bitwidth_prach: 9
  enable_ul_static_compr_hdr: true
  enable_dl_static_compr_hdr: true

If enable_ul_static_compr_hdr is false, you need to activate the checkbox udComprHdr field is present for uplink in wireshark. Same applies for downlink.

Regards,
Alex

[ujjwalpawar]

Thanks for your reply. IQ bitwidth were not matching. Fixed now.