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VIP Super Bronze

VCS-C and Ex90 SDP negotiation

Guys,

I need help getting to understand the following. I have attached the full log for my queries. Please if you have a few minutes to spare, I would appreciate that..

EX90----VCS-C----(cloud OVC)

1. SDP negotiation on codecs eg EX90 because they seem to differ from the traditional SIP offer/answer model

2. Understand the bandwidth and video SDP negotiation

I have attached a log file of a call from the following endpoint

calling number: 72409107

called URI : 52860301@join.verizon.com

Question 1: For a normal SIP offer/answer echange, a UAC/UAS sends an offer and the remote UAC/UAS responds with an answer. In that response the far end selects one out of several codecs (audio and video) to use from the offered list..

Eg This is a jabber call..

+++Here is the offer from one jabber end point+++

v=0

o=Cisco-SIPUA 2469 0 IN IP4 10.245.45.1

s=SIP Call

b=AS:4000

t=0 0

m=audio 22172 RTP/AVP 0 8 18 105 104 101

c=IN IP4 10.245.45.1

a=rtpmap:0 PCMU/8000

a=rtpmap:8 PCMA/8000

a=rtpmap:18 G729/8000

a=fmtp:18 annexb=no

a=rtpmap:105 G7221/16000

a=fmtp:105 bitrate=24000

a=rtpmap:104 G7221/16000

a=fmtp:104 bitrate=32000

++++and here is the answer+++

NB: That a single audio codec has been selected from the offered list..This is how I have always understood things to work until yesterday

v=0

o=CiscoSystemsCCM-SIP 3957141 1 IN IP4 10.105.42.174

s=SIP Call

b=AS:3968

t=0 0

m=audio 22308 RTP/AVP 104 101

c=IN IP4 10.102.140.68

a=rtpmap:104 G7221/16000

a=fmtp:104 bitrate=32000

a=ptime:20

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

m=video 31276 RTP/AVP 97

c=IN IP4 10.102.140.68

b=TIAS:3936000

In the trace file attached,

++++++++Here is an offer from an Ex90+++++++

v=0

o=tandberg 18 1 IN IP4 192.168.2.74

s=-

c=IN IP4 192.168.2.74

b=AS:768

t=0 0

m=audio 2326 RTP/AVP 107 108 109 110 104 105 9 18 8 0 101

b=TIAS:128000

a=rtpmap:107 MP4A-LATM/90000

a=fmtp:107 profile-level-id=25;object=23;bitrate=128000

a=rtpmap:108 MP4A-LATM/90000

a=fmtp:108 profile-level-id=24;object=23;bitrate=64000

a=rtpmap:109 MP4A-LATM/90000

a=fmtp:109 profile-level-id=24;object=23;bitrate=56000

a=rtpmap:110 MP4A-LATM/90000

a=fmtp:110 profile-level-id=24;object=23;bitrate=48000

a=rtpmap:104 G7221/16000

a=fmtp:104 bitrate=32000

a=rtpmap:105 G7221/16000

a=fmtp:105 bitrate=24000

a=rtpmap:9 G722/8000

a=rtpmap:18 G729/8000

a=fmtp:18 annexb=yes

a=rtpmap:8 PCMA/8000

a=rtpmap:0 PCMU/8000

++++And here is the 200 OK (answer) to that offer++++

NB: That the Answer contains a list of supported codecs again!

v=0

o=CODIAN 111980140951222 111980140951222 IN IP4 70.240.240.246

s=-

c=IN IP4 65.240.240.246

b=AS:768

t=0 0

m=audio 16606 RTP/AVP 107 108 109 110 104 105 9 18 8 0 101

a=rtpmap:107 MP4A-LATM/90000

a=rtpmap:108 MP4A-LATM/90000

a=rtpmap:109 MP4A-LATM/90000

a=rtpmap:110 MP4A-LATM/90000

a=rtpmap:104 G7221/16000

a=rtpmap:105 G7221/16000

a=rtpmap:9 G722/8000

a=rtpmap:18 G729/8000

a=rtpmap:8 PCMA/8000

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:107 profile-level-id=25;config=4101731A001100;object=23;bitrate=128000

a=fmtp:108 profile-level-id=24;object=23;bitrate=64000

a=fmtp:109 profile-level-id=24;object=23;bitrate=56000

a=fmtp:110 profile-level-id=24;object=23;bitrate=48000

a=fmtp:104 bitrate=32000

a=fmtp:105 bitrate=24000

a=fmtp:18 annexb=yes

I checked the RFC and it says in scenarios like this, that if the endpoint cant support multiple codec at the same time, it will send a re-invite with only one codec in its SDP. Does that suggest that the video codecs support multiple codecs at the same time? How then do we know the negotiated codec for the call in this scenario for both video and audio calls..

Question 2: In the attached log file, I see

v=0

o=tandberg 18 1 IN IP4 192.168.2.74

s=-

c=IN IP4 192.168.2.74

b=AS:768

t=0 0

--

--

m=video 2328 RTP/AVP 97 126 96 34 31----------------first video M-line

b=TIAS:768000

a=rtpmap:97 H264/90000

a=fmtp:97 packetization-mode=0;profile-level-id=428016;max-br=5000;max-mbps=245000;max-fs=9000;max-smbps=245000;max-fps=6000;max-rcmd-nalu-size=3456000

a=rtpmap:126 H264/90000

a=fmtp:126 packetization-mode=1;profile-level-id=428016;max-br=5000;max-mbps=245000;max-fs=9000;max-smbps=245000;max-fps=6000;max-rcmd-nalu-size=3456000

a=rtpmap:96 H263-1998/90000

a=fmtp:96 custom=1280,768,3;custom=1280,720,3;custom=1024,768,1;custom=1024,576,2;custom=800,600,1;cif4=1;custom=720,480,1;custom=640,480,1;custom=512,288,1;cif=1;custom=352,240,1;qcif=1;maxbr=7680

a=rtpmap:34 H263/90000

a=fmtp:34 cif4=1;cif=1;qcif=1;maxbr=7680

a=rtpmap:31 H261/90000

a=fmtp:31 cif=1;qcif=1;maxbr=7680

a=rtcp-fb:* nack pli

a=rtcp-fb:* ccm fir

a=rtcp-fb:* ccm tmmbr

a=sendrecv

a=content:main

a=label:11

a=answer:full

m=application 5070 UDP/BFCP *

a=floorctrl:c-s

a=confid:1

a=floorid:2 mstrm:12

a=userid:18

a=setup:actpass

a=connection:new

m=video 2330 RTP/AVP 97 126 96 34 31--------------------------------second video M-line

b=TIAS:768000

a=rtpmap:97 H264/90000

a=fmtp:97 packetization-mode=0;profile-level-id=428016;max-br=5000;max-mbps=245000;max-fs=9000;max-smbps=245000;max-fps=6000;max-rcmd-nalu-size=3456000

a=rtpmap:126 H264/90000

a=fmtp:126 packetization-mode=1;profile-level-id=428016;max-br=5000;max-mbps=245000;max-fs=9000;max-smbps=245000;max-fps=6000;max-rcmd-nalu-size=3456000

a=rtpmap:96 H263-1998/90000

a=fmtp:96 custom=1280,768,3;custom=1280,720,3;custom=1024,768,1;custom=1024,576,2;custom=800,600,1;cif4=1;custom=720,480,1;custom=640,480,1;custom=512,288,1;cif=1;custom=352,240,1;qcif=1;maxbr=7680

a=rtpmap:34 H263/90000

a=fmtp:34 cif4=1;cif=1;qcif=1;maxbr=7680

a=rtpmap:31 H261/90000

a=fmtp:31 cif=1;qcif=1;maxbr=7680

a=rtcp-fb:* nack pli

a=rtcp-fb:* ccm fir

a=rtcp-fb:* ccm tmmbr

a=sendrecv

a=content:slides

a=label:12

m=application 2332 RTP/AVP 100

a=rtpmap:100 H224/4800

a=sendrecv

++++In the answer, I see the following m-plines for video..+++++

m=video 16608 RTP/AVP 97 126 96 34 31

b=AS:4000

--

--

m=video 0 RTP/AVP 97

Questions..

1. Why do we have two video m-lines

2. What bandwidth is in use here...The offer has b=TIAS:768000, the answer has b=AS:4000

Which badnwidth modifier deterines what badnwidth is used for the call...TIAS or AS?

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2 REPLIES

VCS-C and Ex90 SDP negotiation

From how I recall it its the freedom of the device to say which codecs it supports.

Maybe it were the devices which you used before which only selected one codec. ;-)

Which means that the device could switch without a reinvite in between the

announced codecs. You have the RTP payload type so the devices should

know what they receive and how to handle them.

main video:

m=video 2328 RTP/AVP 97 126 96 34 31----------------first video M-line

a=content:main

content / presentation / "slide" channel:

m=video 2330 RTP/AVP 97 126 96 34 31--------------------------------second video M-line

a=content:slides

Regards AS/TIAS, check out rfc3890 and:

http://www.cisco.com/c/en/us/td/docs/routers/asr1000/configuration/guide/sbcu/2_xe/sbcu_2_xe_book/sbc_sdpbw.html#wp1060658

In short: AS for the whole session TIAS for the specific media

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VIP Super Bronze

VCS-C and Ex90 SDP negotiation

Thanks martin..

On the first question...If you  look at the jabber trace frace files I posted, you will see that the offer includes a list of codec. When the other endpoint which is also a jabber client answered, it only selected one codec. It definitely can support all the codes offered, but it picked one..

On the Ex90 logs, there I just see the same list of codecs offered in the answer and unless you look at the EX90 controller, you cant tell which audio or video codec its using...

Please rate all useful posts

"The essence of christianity is not the enthronement but the obliteration of self --William Barclay"

Please rate all useful posts "The essence of christianity is not the enthronement but the obliteration of self --William Barclay"
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