[cisco-voip] Comfort noise RTP
Mark Holloway
mh at markholloway.com
Thu Aug 8 11:33:59 EDT 2013
This is incredibly odd. I don't see a payload of 13 or an rtpmap with CN. Are you sure you have the entire frame included? I would be curious to see a pcap SIP ladder diagram of the call flow. That SDP is huge. I wouldn't be surprised if something in that SDP is triggering the abnormal behavior. :)
On Aug 8, 2013, at 6:33 AM, Seth McGuinness <Seth.McGuinness at imaginegroup.ie> wrote:
> Hello All,
>
> We have a customer complaining about Comfort Noise generating from our Cisco AS5400, strange thing is that the packet traces suggest that the request for comfort noise generation comes from the client SIP invite, I can’t see where this is the case in the invite.
>
> Client invite
>
> No. Time Source Destination Protocol Length Info
> 1 2013-08-07 09:21:34.500695 10.10.1.1 192.168.1.1 SIP/SDP 1131 Request: INVITE sip:+197831111111149 at 192.168.1.1;user=phone, with session description
>
> Frame 1: 1131 bytes on wire (9048 bits), 1131 bytes captured (9048 bits)
> Ethernet II, Src: WwPcbaTe_11:11:11 (00:0f:1f:11:11:11), Dst: BrocadeC_22:22:22 (00:1b:ed:22:22:22)
> Internet Protocol Version 4, Src: 10.10.1.1(10.10.1.1), Dst: 192.168.1.1 (192.168.1.1)
> User Datagram Protocol, Src Port: sip-tls (5061), Dst Port: sip (5060)
> Session Initiation Protocol
> Request-Line: INVITE sip:+197831111111149 at 192.168.1.1;user=phone SIP/2.0
> Message Header
> Message Body
> Session Description Protocol
> Session Description Protocol Version (v): 0
> Owner/Creator, Session Id (o): - 1375863694 1375863694 IN IP4 10.10.1.1
> Owner Username: -
> Session ID: 1375863694
> Session Version: 1375863694
> Owner Network Type: IN
> Owner Address Type: IP4
> Owner Address: 10.10.1.1
> Session Name (s): -
> Connection Information (c): IN IP4 10.10.1.1
> Connection Network Type: IN
> Connection Address Type: IP4
> Connection Address: 10.10.1.1
> Time Description, active time (t): 0 0
> Session Start Time: 0
> Session Stop Time: 0
> Media Description, name and address (m): audio 33870 RTP/AVP 8 0 18 101
> Media Type: audio
> Media Port: 33870
> Media Protocol: RTP/AVP
> Media Format: ITU-T G.711 PCMA
> Media Format: ITU-T G.711 PCMU
> Media Format: ITU-T G.729
> Media Format: DynamicRTP-Type-101
> Media Attribute (a): rtpmap:8 PCMA/8000
> Media Attribute Fieldname: rtpmap
> Media Format: 8
> MIME Type: PCMA
> Sample Rate: 8000
> Media Attribute (a): rtpmap:0 PCMU/8000
> Media Attribute Fieldname: rtpmap
> Media Format: 0
> MIME Type: PCMU
> Sample Rate: 8000
> Media Attribute (a): rtpmap:18 G729/8000
> Media Attribute Fieldname: rtpmap
> Media Format: 18
> MIME Type: G729
> Sample Rate: 8000
> Media Attribute (a): fmtp:18 annexb=no
> Media Attribute Fieldname: fmtp
> Media Format: 18 [G729]
> Media format specific parameters: annexb=no
> Media Attribute (a): rtpmap:101 telephone-event/8000
> Media Attribute Fieldname: rtpmap
> Media Format: 101
> MIME Type: telephone-event
> Sample Rate: 8000
> Media Attribute (a): fmtp:101 0-15
> Media Attribute Fieldname: fmtp
> Media Format: 101 [telephone-event]
> Media format specific parameters: 0-15
> Media Attribute (a): sendrecv
> Media Attribute (a): silenceSupp:off - - - -
> Media Attribute Fieldname: silenceSupp
> Media Attribute Value: off - - - -
>
>
> Our response
>
> No. Time Source Destination Protocol Length Info
> 2 2013-08-07 09:21:41.862610 192.168.1.1 10.10.1.1 RTP 60 PT=Comfort noise, SSRC=0x8FED3F6, Seq=28259, Time=1374861414
>
> Frame 7: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)
> Ethernet II, Src: BrocadeC_22:22:22 (00:1b:ed:22:22:22), Dst: WwPcbaTe_11:11:11 (00:0f:1f:11:11:11)
> Internet Protocol Version 4, Src: 192.168.1.1 (192.168.1.1), Dst: 10.10.1.1(10.10.1.1)
> User Datagram Protocol, Src Port: 19578 (19578), Dst Port: 33870 (33870)
> Real-Time Transport Protocol
> [Stream setup by SDP (frame 1)]
> 10.. .... = Version: RFC 1889 Version (2)
> ..0. .... = Padding: False
> ...0 .... = Extension: False
> .... 0000 = Contributing source identifiers count: 0
> 0... .... = Marker: False
> Payload type: Comfort noise (13)
> Sequence number: 28259
> [Extended sequence number: 93795]
> Timestamp: 1374861414
> Synchronization Source identifier: 0x08fed3f6 (150918134)
> Payload: 48
>
> In our RTP Comfort noise payload type 13 in frame(2) it states that the Stream has been setup by SDP in frame 1, I can’t see this in frame 1, it has silence suppression turned off and annexb=no, the RTP stream is G.711 anyway, I left out the whole capture for brevity. Has anyone come across this? Any suggestions appreciated and apologies if I post this in the wrong place!
>
> Cheers
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