rafan 的筆記本

Why payload type in RTP is necessary (even with SIP)?
- due to RED?
How to calculate jitter?
for each received RTP packet, you know when it was sent (RTP Timestamp) and when it is received.. so.. just do it. also check RFC 1889 A.8
Why source description packet needed even with SIP
sip registers with multiplue server
- failure tolerance
- multiple registration: multiple locations (follow-me) ringing

final

elaborate on the principles of integration on SIP & QoS mechanism
STUN
- describe how STUN works for most NATs
- describe why STUN can not work on Symmetric NAT
- describe Binding Lifetime Determination in STUN
describe the adv. of separation of media and call control
(SIP-to-PSTN gateway based on MGCP) Draw network arch. and describe message flow for SIP terminal calling a telephone on PSTN.
describe issues discussed in IETF SIGTRAN
describe concepts of Softswitch, compare it with existing Hard/Circulted-switch
<i>in what scenario will Softswitch be a selection for VoIP service?</i>
Design a VoIP Netowrk
- blocking probability? calculate?
- factors does the required bandwidth for a single call depend on?