tel500-voice communications session initiation protocol improvement using inter- asterisk exchange...
TRANSCRIPT
TEL500-Voice Communications
Session initiation protocol improvement using inter-asterisk exchange
Devesh Mendiratta & Sameer DeshmukhMS-Telecommunication
State University of New York Institute of Technology
Introduction VOIP Network VOIP Protocols
• SIP (Session initiation protocol)• IAX (inter-asterisk exchange Protocol)
Codecs
Bandwidth Utilization over VoIP Networks
Theoretical bandwidth calculation
Comparison Practical bandwidth calculation
Introduction cont.
SIP Protocol
Session Layer Protocol “Request and Response” Mechanism Sessions & Video data between two endpoints File types & formats After establishing a session – responsibility of
average flow transfer is delegated to RTP i.e. Transport layer
Dynamically allocation of port (10000 to 20000)
IAX Protocol
Session layer protocol Provides control & VoIP networks Point-to-point Media & signaling protocol Multiplexing of signaling UDP port 4569 Trunked IAX
Codecs
Analog voice is converted to a digital signal
Then it is carried across the Internet. Examples based on compression level
G.711G.726
G.729AGSMiLBCSpeexMP3
Calculation : Theoretical Value
Codec bit rate = (codec sample size)/(codec sample interval)
Packets per seconds = (codec bit rate)/(voice payload size)
Total packet size = L2 + IP + UDP + L5 + voice payload size
The BW required for n conversations full duplex:
BWn = BW x n x 2
CSI = 10ms
CSS = 80 bytes
VPS = 160 bytes
BW30calls = 87.2 Kbps x 30 x 2 = 5232 Kbps
Example : SIP using codec G.711
Calculation : Theoretical ValueBW Calculation Protocol SIP – codec G.711
Input data: CSI = 10 ms,CSS = 80 bytes, VPS = 160 bytes
BW30calls = 87.2 Kbps x 30 x2 = 5232 Kbps (more than 5 Mbps)
BW Calculation Protocol SIP – GSM codec
Input data: CSI = 10 ms,CSS = 80 bytes, VPS = 160 bytes
BW30calls = 36.4 Kbps x 30 x 2 =2184 Kbps (near 2 Mbps)
IAX Protocol – G.711 codec
Input data: CSI = 10 ms,CSS = 80 bytes, VPS = 160 bytes,
CBR = 64 Kbps, VPS (ms) = 20 ms,PPS = 50
BW30calls = 84 Kbps + 65.6 Kbps x 29 =1986.4 Kbps (near 2 Mbps)
H.IAX Protocol – codec GSM
Input data: CSI = 20 ms,CSS = 33 bytes, VPS = 33 bytes,
CBR = 13.2 Kbps, VPS (ms) = 20 ms,PPS = 50
BW30calls = 33.2 Kbps + 14.8 Kbps x 29 = 462.4 Kbps (Less than 512 kbps)
Practical Value
Vyatta installation Configuring interfaces & static routs on Vyatta Installing CentOS 5.2 OS on servers Asterisk 1 & 2 Installing Asterisk PBX on servers 1 & 2 Installing Wireshark & Unsniff sniffer on the machine SIP & IAX extensions settings Dial plan configuration
Conclusion
SIP & G.711 codec => very good quality of voice highest consumption of BW
IAX & GSM codec => lowest consumption of BW high traffic – distortion
IAX & G.711 codec => ideal for power traffic level is relatively high requires high bandwidth
SIP & GSM codec => ideal for plans that do not
support IAX
Resources
• ^http://ofps.oreilly.com/titles/9781449332426/asterisk-UnderstandingVoIP.html
• ^http://en.wikipedia.org/wiki/Category:VoIP_protocols
• ^http://www.cisco.com/application/pdf/en/us/guest/tech/tk587/c1506/ccmigration_09186 a008012dd36.pdf