Hello, thank you for great work.

I use last version (git master)  librohc 2.0
- I try with diffrent configurations small cid  and large cid, W-LSB side is standard (4) try set 8 with same result, try  ROHC_U_MODE and ROHC_O_MODE
- Profiles enabled: ROHC_PROFILE_IP ROHC_PROFILE_UDP ROHC_PROFILE_RTP
- Only ICMP packets
- This happends only then run multiple ping's (I try with 20 several paralles ping's to same host ). This single ping all works fine even if I enable flood mode.
- Loss & delay emulated with netem. Loss: 0.5% Delay: 30ms. As I see if channel are lossless I observer no problems like this.

Today I got another kind of error.
20 parallels ICMP ping's 
Loss: 0.5% Delay: 30ms
ROHC_LARGE_CID, ROHC_LARGE_CID_MAX, bits: 8 O_MODE
one side just stop decompress everything and send no feedback's at all

---- PROBLEM SIDE ---
On feedback recieved from remote side ----------
[rohc_decomp.c:780 rohc_decompress3()] decompress the 3-byte packet #84598
[rohc_decomp.c:3645 rohc_decomp_parse_padding()] skip 0 byte(s) of padding
[rohc_decomp.c:3859 rohc_decomp_parse_feedbacks()] parse feedback item #1 at offset 0 in ROHC packet
[rohc_decomp.c:3921 rohc_decomp_parse_feedback()] feedback found (header = 1 bytes, data = 2 bytes)
[rohc_decomp.c:1024 d_decode_header()] decompressor received 3 bytes of feedback for the same-side associated compressor
[rohc_decomp.c:1033 d_decode_header()] feedback-only packet, stop decompression
[rohc_decomp.c:855 rohc_decompress3()] packet decompression succeeded
[rohc_comp.c:1910 rohc_comp_deliver_feedback2()] deliver 3 byte(s) of feedback to the right context
[rohc_comp.c:1938 rohc_comp_deliver_feedback2()] feedback found (header = 1 bytes, data = 2 bytes)
[rohc_comp.c:1812 __rohc_comp_deliver_feedback()] deliver 2 byte(s) of feedback to the right context
[rohc_comp.c:2756 rohc_comp_feedback_parse_cid()] feedback CID = 0
[rohc_comp_rfc3095.c:924 rohc_comp_rfc3095_feedback()] FEEDBACK-1 received
[rohc_comp_rfc3095.c:932 rohc_comp_rfc3095_feedback()] ACK received (CID = 0, 8-bit SN = 0x68)
[rohc_comp_rfc3095.c:1132 rohc_comp_rfc3095_feedback_ack()] ACK(O) received, but not supported, so do not transit to SO state more quickly
[rohc_comp_rfc3095.c:1220 rohc_comp_rfc3095_feedback_ack()] ACK received, but not fully supported, so do not acknowledge compressed list more quickly
[rohc_comp.c:1866 __rohc_comp_deliver_feedback()] FEEDBACK-1 data successfully handled

On decompress ---------------------------------
[    0.000] PRT F:tdx_deasm_raw: GOT TDX_PKT_T_RAW SEQ=89089 rohc=YES
[    0.000] FLW F:tdx_flow_raw_serialized: RAW_SEQ=89089 LAST_SEQ=89088
[rohc_decomp.c:780 rohc_decompress3()] decompress the 67-byte packet #84599
[rohc_decomp.c:3645 rohc_decomp_parse_padding()] skip 0 byte(s) of padding
[rohc_decomp.c:1024 d_decode_header()] decompressor received 0 bytes of feedback for the same-side associated compressor
[rohc_decomp.c:3608 rohc_decomp_decode_cid()] 1-byte large CID = 0
[rohc_decomp.c:3762 rohc_decomp_find_context()] context with CID 0 found
[rohc_decomp.c:1180 d_decode_header()] 6 bits required for SN in feedback (6 bits required for RTT, 16 max)
[rohc_decomp.c:1199 d_decode_header()] decode packet as 'UO-1'
[rohc_decomp.c:1210 d_decode_header()] packet 'UO-1' (3) does not carry static information, it cannot be received in No Context state
[rohc_decomp.c:832 rohc_decompress3()] stay in O-mode as requested by user
[rohc_decomp.c:889 rohc_decompress3()] packet decompression failed: malformed packet (2)
[rohc_decomp.c:2033 rohc_decomp_feedback_nack()] CID 0: O-mode: No Context state: UO-1 packet received
[rohc_decomp.c:2174 rohc_decomp_feedback_nack()] rate-limiting successive feedbacks (100 of 3200 with threshold 64)
[rohc_decomp.c:2206 rohc_decomp_feedback_nack()] do not send a negative ACK
[rohc_decomp.c:2298 rohc_decomp_feedback_nack()] do not perform a downward state transition
[    0.000] COM F:tdx_rohc_decomp: Can't decompress ROHC packet. status=2 ('malformed packet') CRC=0xA47AC720
[      0000]   A5 00 C5 00 00 BF D2 5D   47 14 F9 1E D1 96 56 00   ........ G.....V.
[      0016]   00 00 00 54 F2 05 00 00   00 00 00 10 11 12 13 14   ...T.... ........
[      0032]   15 16 17 18 19 1A 1B 1C   1D 1E 1F 20 21 22 23 24   ........ ........
[      0048]   25 26 27 28 29 2A 2B 2C   2D 2E 2F 30 31 32 33 34   ........ ...01234
[      0064]   35 36 37                                            567

tommorow I try to send you a traffic dumps with  all logs and library configuration.