Re: GPRS' PDCH idle filling

Luca Melette pointed out that I can compile gprs_decode with "-DRLC_DEBUG" which will enable sending RLC/MAC frames to Wireshark with GSMTAP: diff --git a/Makefile b/Makefile index 9e95f07..2e6737b 100644 --- a/Makefile +++ b/Makefile @@ -1,5 +1,5 @@ default: - gcc -O2 -g -o gprsdecode main.c bit_func.c viterbi.c process.c gsm_interleave.c cch.c crc.c -pthread -losmogsm -losmocore + gcc -O2 -g -o gprsdecode main.c bit_func.c viterbi.c process.c gsm_interleave.c cch.c crc.c -pthread -losmogsm -losmocore -DRLC_DEBUG gcc -O2 -g -o synmux synchro_muxer.c clean: Then I just have to set correct GASMTAP channel type value and I can see GPRS RLC/MAC messages in Wireshark. E.g. for the latest stock Wireshark patch looks like this: diff --git a/output.c b/output.c index b720187..7d5840d 100644 --- a/output.c +++ b/output.c @@ -14,7 +14,7 @@ void net_init() void net_send_rlcmac(uint8_t *msg, int len, uint8_t ul) { if (gti) { - gsmtap_send(gti, ul?ARFCN_UPLINK:0, 0, chantype_rsl2gsmtap(0x08, 0x80), 0, 0, 0, 0, msg, len); + gsmtap_send(gti, ul?ARFCN_UPLINK:0, 0, 0x0b, 0, 0, 0, 0, msg, len); while (osmo_select_main(1)); } Attached .pcap files are generated this way from captures, provided by Karsten and Luca at http://srlabs.de/gprs/ You can open them with the latest Wireshark and they will be correctly decoded (as far as dissector is implemented). E.g. this allowed us to see those filler messages I was asking about. Now, Osmocom's gsmtap.h have different channel ID's then gsmtap from stock Wireshark. Does that mean that Osmocom's Wireshark have different dissector implementation for PDCH/PACCH/PTCCH/etc then the stock one? Which one is more advanced? On Fri, Oct 7, 2011 at 13:12, Alexander Chemeris <alexander.chemeris(a)gmail.com> wrote: -- Regards, Alexander Chemeris.