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Bug #2701

RTCP SDES contains bogus information

Added by laforge 12 days ago. Updated 12 days ago.

Status:
In Progress
Priority:
Low
Assignee:
Category:
-
Target version:
-
Start date:
12/03/2017
Due date:
% Done:

90%

Spec Reference:

Description

When looking at the RTCP generated by osmo-bts, we see bogus content, such as "unknown@unknown" as CNAME and only the ORTP version as "TOOL" name.

Would be better to use libortp's rtp_session_set_source_description() API to put in some reasonable values. Of course RFC3550 didn't assume/expect GSM / cellular usage, so the recommendations for the content of CNAME, NAME, EMAIL, PHONE and TOOL sdes items are not entirely applicable.

I would suggest we use something that makes it easy to map the RTP stream to what it is used for. So on Abis, the BTS unit-id as well as the timeslot/sub-slot definitely should be encoded somehow to aid the mapping of RTP streams to physical GSM resources. The MSISDN is unfortunately not known to the BTS, so "PHONE" cannot reasonably be filled-in :(

History

#1 Updated by laforge 12 days ago

  • Status changed from New to In Progress
  • Assignee set to laforge
  • % Done changed from 0 to 90

#2 Updated by laforge 12 days ago

Internet Protocol Version 4, Src: 127.0.0.1, Dst: 127.0.0.1
User Datagram Protocol, Src Port: 10351, Dst Port: 3334
Real-time Transport Control Protocol (Sender Report)
Real-time Transport Control Protocol (Source description)
    [Stream setup by GSM A- (frame 15075)]
    10.. .... = Version: RFC 1889 Version (2)
    ..0. .... = Padding: False
    ...0 0001 = Source count: 1
    Packet type: Source description (202)
    Length: 20 (84 bytes)
    Chunk 1, SSRC/CSRC 0x318C8FD4
        Identifier: 0x318c8fd4 (831295444)
        SDES items
            Type: CNAME (user and domain) (1)
            Length: 13
            Text: bts@127.0.0.1
            Type: NAME (common name) (2)
            Length: 23
            Text: (bts=0,trx=0,ts=2,ss=0)
            Type: LOC (geographic location) (5)
            Length: 8
            Text: 1234/0/0
            Type: TOOL (name/version of source app) (6)
            Length: 21
            Text: OsmoBTS-0.6.0.24-6bf9
            Type: END (0)

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