Bug #2654
closedosmo-mgw silently ignores unsuppoerted packetization interval
100%
Description
When the call agent specifies an unsupported packetization interval, the MGW must reject it with error code 535. osmo-mgw however seems to completely ignore it and go ahead.
TC_crcx_unsupp_packet_intv
has been created for it and so far fails.
Updated by dexter about 6 years ago
The local connection options are parsed in mgcp_protocol.c in:
static void set_local_cx_options(void *ctx, struct mgcp_lco *lco,
const char *options)
This function could get a return code which causes CRCX/MDCX to fail when invalid options are passed. The packetization interval is defined by a fixed value L: p=X or as a range L: p=X-Y. I wonder what is valid here.
By the unittest I can see 20 or 20-40 is common here, but I am not sure if this are the only range/values that is valid here. Is there some table where I can find valid ranges. For GSM uses it will be 20ms for most of the time, but maybe there are other valid uses that have different packetization intervals?
Updated by dexter about 6 years ago
- Status changed from New to In Progress
- % Done changed from 0 to 100
We now check if the packetization interval is a multiple of 20ms. This is what is commonly used in practice. I suppose in theory someone could use an interval of 111ms, but that would be fanciful. The TTCN3 test passes now. The patch is up for review in gerrit: https://gerrit.osmocom.org/6218
Updated by laforge about 6 years ago
FYI, I found that 3GPP TS 48.103 5.4.2.3 states explicitly that the RTP packetization time in GSM is 20ms
for all codecs.