The beauty with Asterisk is you start with the software and you add the hardware around it. Given these

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Extending Open Source PBX For Scalable Media Gateways Presented by: Nenad Corbic, B.Eng Chief Software EngineerSoftware Manager Sangoma Technologies2-Jun-08 / 1Limitations of Current Soft PBX Architecture• Monolithic/Single Server Architecture. • TDM Bottleneck (Zaptel/TDM Hardware)• Software Echo Cancellation & DTMF & D-Chan HDLC• Software Codec (g729)• Kernel / User Space Context Penalty• TDM Clustering Solutions limited and hard to configure• Customer need for 16 x E1 =~ 500 calls or greater !2-Jun-08 / 2Current Asterisk Open Source PBX ModelAsterisk PBXlibprichan_zap.sochan_sip.soIPIPZAPTEL Kernel SpaceTDM TDM T1/E1T1/E1Drivers/Hardware(Sangoma/Digium)2-Jun-08 / 3Hardware Interrupt Penalty: SW EC & DTMF Asterisk PBXsipiaxIPchan_zap.so / libpri/dev/zap/ 0 1 2 3 4 5 6 7 8 9 10 … 245 246… 500... 600Kernell ZAPTEL SpaceSpaceSoft EC and DCHAN HDLChw_isr() 1000 isr / sec * spans1ms 1ms 1ms 1ms 1ms1ms 1ms 1ms 1ms8byt 8byt 8byt 8byt 8byt8byt 8byt 8byt 8bytTDM Drivers/Hardware (Sangoma/Digium)T1/E1/BRI/Analog2-Jun-08 / 4HW Optimizations: EC & DTMF & DCHAN HDLC Asterisk PBX sipiaxIPchan_zap.so / libpri/dev/zap/ 0 1 2 3 4 5 6 7 8 9 10 … 245 246… 500... 600Kernell SpaceeZAPTEL hw_isr() 100 isr / sec10ms 10ms 10ms 10ms 10ms 10ms 10ms 10ms80byt 80byt 80byt 80byt 80byt 80byt 80byt 80bytHardware Echo Cancellellation & DTMF & DCHAN HDLCTDM Drivers/Hardware (Sangoma/Digium)T1/E1/BRI/Analog2-Jun-08 ...

Informations

• Publié par: Irkoi
• Nombre de lectures: 20
• Langue: English

Extrait

Extending Open Source PBX For Scalable Media Gateways

Presented by: Nenad Corbic, B.Eng Chief Software Engineer Software Manager Sangoma Technologies

2-Jun-08 / 1

Limitations of Current Soft PBX Architecture

• • • • • • •

Monolithic/Single Server Architecture. TDM Bottleneck (Zaptel/TDM Hardware) Software Echo Cancellation & DTMF & D-Chan HDLC Software Codec (g729) Kernel / User Space Context Penalty TDM Clustering Solutions limited and hard to configure Customer need for 16 x E1 =~ 500 calls or greater !

2-Jun-08 / 2

Current Asterisk Open Source PBX Model

IP

T1/E1

Asterisk PBX

chan_sip.so

libpri chan_zap.so

ZAPTEL

TDM Drivers/Hardware (Sangoma/Digium)

Kernel Space

2-Jun-08 / 3

Hardware Interrupt Penalty: SW EC & DTMF

IP

Asterisk PBX sip iax

chan_zap.so / libpri

/dev/zap/ 0 1 2 3 4 5 6 7 8 9 10 … 245 246… 500... 600

ZAPTEL Soft EC and DCHAN HDLC

hw isr() 1000 isr / sec * spans _

T1/E1/BRI/Analog

1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 8byt 8byt 8byt 8byt 8byt 8byt 8byt 8byt 8byt

TDM Drivers/Hardware (Sangoma/Digium)

Kernel S p a c e

2-Jun-08 / 4

HW Optimizations: EC & DTMF & DCHAN HDLC

IP

Asterisk PBX sip iax

chan_zap.so / libpri

/dev/zap/ 0 1 2 3 4 5 6 7 8 9 10 … 245 246… 500... 600

hw_isr() 100 isr / sec

T1/E1/BRI/Analog

ZAPTEL

10ms 10ms 10ms 10ms 10ms 10ms 10ms 10ms 80byt 80byt 80byt 80byt 80byt 80byt 80byt 80byt

Hardware Echo Cancellation & DTMF & DCHAN HDLC TDM Drivers/Hardware (Sangoma/Digium)

Kernel Space

2-Jun-08 / 5

• • • • • •

Kernel Context Penalty

Greater the number of kernel devices, the greater the context penalty. System doesn t scale over 500 individual channels. ’ Where each channel receives its own kernel device. Solution is to move to a per span kernel device. This way all channels inside a span are read in a same kernel context. Stage two solution is to memory map user space into kernel space and have zero copy transfers from kernel to user space.

2-Jun-08 / 6

Create kernel device per Span

IP

Asterisk PBX

sip

iax

chan_zap.so / libpri

span channelization

/dev/zap/span/ 0 1 2 3 4 5 6 7 8 9 10 .. 28

ZAPTEL

TDM Drivers/Hardware (Sangoma/Digium)

Kernel Space

2-Jun-08 / 7

The Distributed TDM Architecture: Woomera

•

•

•

•

•

Started as a response to a business need

Providing a carrier-grade SS7 interface to Asterisk and others.

A need to support 16 + E1 lines.

Woomera Protocol: TCP Control Socket + UDP Media Socket (Woomera offers leverage)

Design a Generic Channel Driver using Woomera for Asterisk.

2-Jun-08 / 8

Woomera Asterisk PBX Model

IP

Asterisk Open PBX

chan_sip.so chan woomera.so _ (Client)

TCP Control Msg

UDP Media

Signal / Media Gateway

Woomera Server

voice

dchan

TDM API Drivers/Hardware

2-Jun-08 / 9

• • •

• •

Woomera Control Protocol

TEXT based Call Control Messages (carried over TCP) HELLO, CALL, HANGUP, LISTEN, ACCEPT, ANSWER, DTMF, BYE/QUIT Each command is transmitted in ASCII text format

EVENT HELLO CALL Version: 1.0 bri:g1/9054741990 Supported-Protocols: Raw-Audio: 192.168.1.1:9000 h323,sip,iax.ss7,pri,bri Request-Audio: raw

ACCEPT EVENT MEDIA Unique-Call-Id: id1 Unique-Call-Id: id1 Raw-Audio:192.168.1.1:9000

UDP based: Media (ulaw,alaw,PMC-16…) RFC in progress…

2-Jun-08 / 10

Sangoma Woomera TDM Architecture

IP

chan_sip Aster isk

_ chan woomera

TCP Control

UDP Media

Sangoma Signal Media Gateway

Woomera Signal Server Translato r

T1/E1/BRI/Analog

LibSangoma (Media)

TDM API Flexible RX/TX Period Codec Translation B Channelizatoin

Signaling Stacks SS7 ISDN RBS

B{1-1 5 } |   D {1 6 } |  B { 1 7 -31}

MTP2 or Q921

2-Jun-08 / 11