SDP PARAMETERS

[haryramani]

Hai ,

Am very very new to this field, Can someone please tell how SDP parameters are fetched??

Is it like the paramters are fetched by us or it fetches automatically?? If it is fetched automatically can some1 brief it How ?

Am into researching this topic but i couldnt find this one...And also if possible can sum1 tell me how to get an example of sdp through wireshark without IP phone?? I tried using streaming video through my player and capture RTP or RTSP protocol?? But it couldnt capture...

[Manish Prasad]

Is it like the parameters are fetched by us or it fetches automatically?? --- Its fetched automatically on the basis of what we have configured on end points, call servers and gateways.

And also if possible can sum1 tell me how to get an example of sdp  through wireshark without IP phone?? I tried using streaming video  through my player and capture RTP or RTSP protocol?? --- SDP parameters floats with SIP (INVITE,OK) messages , so you need to capture SIP packets to look at SDP parameters like this...

Content-Type: application/sdp

Content-Length: 234

v=0

o=CiscoSystemsCCM-SIP 9136 1 IN IP4 10.129.69.79

s=SIP Call

c=IN IP4 10.129.0.45

b=TIAS:64000

b=AS:64

t=0 0

m=audio 24722 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=ptime:20

a=rtpmap:101 telephone-event/8000

a=fmtp:101

Now to know what all attributes and content means in SDP , i would recommend go through SDP rfc http://tools.ietf.org/html/rfc4566 in details.

Rate all the helpful post.

Thanks

Manish

[haryramani]

Thank u so much..I have already referred to that paper,  I just want to know 2 things

1) There are like 2 types of parameters a mandatory parameter and optional parameters, On what basis these optional parameters are set and how and who picks these optional ones?

2) Is it possible to capture sip without using a IP phone with just some softwares packages?If yes,How?

[Manish Prasad]

Hi Harish,

I will tell what I know on SDP parameters...

1. SDP optional parameters are not generally used in every SIP call , its depend upon the end point capability to insert available features with them (in defined structure) inside SDP. Like e-mail , phone number , conference etc.

2. SIP is application layer protocol for IP telephony , so you need to have an some IP telephony device to initiate SIP messages. If you don't have any hardware you can go for soft phone (Xlite) and SIP server (Asterisk) which are free on internet. Google some installation document on these products. I think that will help you to get to know SIP messages and thier header files.

Thanks

Manish