Working with snooper:
what happens when user initiates Lync call:
1. Invite:
From address , To address & Unique Call id:
2. Static
code : 180. early media: Before initiating call Lync will negotiate information
about specific client through session deceptive protocol(SDP) built on
top of SIP
3. SDP:
Contains Session Id, Client IP, Destination IP, TCP , UDP, TRP headers.
4. First
Lync client will send candidate information
5. Ack
from 2nd client to 1st client saying that am available
,busy etc.
6. 2nd
client will share SDP information saying that will you be able to
communicate ?
7. SIP
signaling will go this can be a ring , desktop sharing , IM popup.
8. When
user answer the call, Other client doesn’t know the other client location it
could be LAN, WAN, Internet.
9. ICE:
Internet connectivity establishment. It is the protocol used to travers over
firewalls.
10. If we
have two firewalls between the client networks then ICE will come into the
picture it will use STUN & TURN to find out how can connect these two
clients
11. After
exchanging the IP address and if they are belongs to same subnet then the call
will be Peer-to-Peer. SIP Signaling stick to server.
12. There
will be 3-5 negotiation happen between the networks i.e., possible network via
Intranet, Internet, WAN, Peer-to-Peer tec. And these negation happens
simultaneously.
13. There
is option available to switch over to another path.
14. Early
media will calculate the Least cost IP to reach or connect with client. After
establish the call if early media identifies that another path is Least cost IP
then it will switch over to another path.
15. Invite,
ACK, SDP, ICE, STUN & TRUN, PUSH(Actual media)
16. Bye:
Disconnect the session.