Leveraging Asterisk to Leveraging Asterisk to Deliver Large Scale Deliver Large Scale VoIP Services in a VoIP Services in a

Carrier EnvironmentCarrier Environment

JR RichardsonJR Richardson

Early VoIP EnvironmentEarly VoIP Environment

Telecom Act of 1996, mass competition, Telecom Act of 1996, mass competition, Telco's needed value add features and Telco's needed value add features and capabilities, VoIP held great potentialcapabilities, VoIP held great potentialVoIP services very immature and costlyVoIP services very immature and costlyHardware VoIP solutions expensive with Hardware VoIP solutions expensive with few features compared to POTSfew features compared to POTSSoftware VoIP existed but PC platform Software VoIP existed but PC platform processor speeds too low for mass scaleprocessor speeds too low for mass scale

What is Asterisk?What is Asterisk?

Open Source Hybrid TDM and packet Open Source Hybrid TDM and packet voice PBX and IVR platformvoice PBX and IVR platformRuns on general computing platformRuns on general computing platformAnalog and Digital telephony interfacesAnalog and Digital telephony interfacesSupports SIP, H323, MGCP, SCCP and Supports SIP, H323, MGCP, SCCP and IAX2IAX2Dial Plan scripting bound only by Dial Plan scripting bound only by imagination of administratorimagination of administrator

Hot Debate: Hardware or Software Hot Debate: Hardware or Software DSP?DSP?

Digital Signal Processing has been a Digital Signal Processing has been a barrier to low cost VoIP servicesbarrier to low cost VoIP servicesHardware solutions are high cost in natureHardware solutions are high cost in natureSoftware DSP technology has been Software DSP technology has been around for years but PC performance lowaround for years but PC performance lowPC performance has increased enough to PC performance has increased enough to warrant investigation into large scale soft warrant investigation into large scale soft switch solutionsswitch solutions

Hardware vs. Software DSP Hardware vs. Software DSP ExerciseExercise

Critical planning event for VoIP Critical planning event for VoIP deployment, calculate PSTN access, TDM deployment, calculate PSTN access, TDM to Packet Voice to Packet Voice transcodingtranscodingLarge Scale Large Scale –– 200K line side extensions200K line side extensionsTrunk ratio 7:1Trunk ratio 7:128,571 DSP channels required28,571 DSP channels required

Hardware DSP CostHardware DSP Cost

Lowest price Dialogic hardware, 2xT1 PCI Lowest price Dialogic hardware, 2xT1 PCI card, $7,999card, $7,999Assuming volume discounts @ 50%, Assuming volume discounts @ 50%, $4000/2xT1 card achievable$4000/2xT1 card achievableCalculation comes to $83/port ($4000/48)Calculation comes to $83/port ($4000/48)28,571 trunks / 24 ports per T1 = 1191 28,571 trunks / 24 ports per T1 = 1191 T1’s needed / 2 T1’s per card = 596 cardsT1’s needed / 2 T1’s per card = 596 cards596 cards x $4000 = $2,384K596 cards x $4000 = $2,384K

Software DSP CostSoftware DSP Cost

Digium 4xT1 cards list $1500Digium 4xT1 cards list $1500Assuming volume discounts @ 50%, Assuming volume discounts @ 50%, $750/4xT1 card achievable $750/4xT1 card achievable (is Mark Spencer watching?)(is Mark Spencer watching?)

Calculation comes to $7.80/port ($750/96)Calculation comes to $7.80/port ($750/96)28,571 trunks / 24 ports per T1 = 1191 28,571 trunks / 24 ports per T1 = 1191 T1’s needed / 4 T1’s per card = 298 cardsT1’s needed / 4 T1’s per card = 298 cards298 cards x $750 = $223,500298 cards x $750 = $223,5001/101/10thth the cost of hardware DSP cardsthe cost of hardware DSP cards

Processor LoadingProcessor Loading

Sending Sending transcodingtranscoding function to central function to central CPU has trade offs, processor loadingCPU has trade offs, processor loadingTo utilize all 96 channels on 4xT1 card, To utilize all 96 channels on 4xT1 card, the server must be robust, driving up costthe server must be robust, driving up costDual Zeon 2.8GHz, 1 Gig RAM, SCSI HDDual Zeon 2.8GHz, 1 Gig RAM, SCSI HDWith strong vendor relations, can achieve With strong vendor relations, can achieve server cost @ $2000server cost @ $2000With 1 With 1 -- 4xT1 Digium card per server, 298 4xT1 Digium card per server, 298 are servers neededare servers needed

Processor Loading (cont)Processor Loading (cont)

298 servers x $2000 = $596K298 servers x $2000 = $596KWith hardware DSP cards, same server With hardware DSP cards, same server could easily handle 4 cardscould easily handle 4 cardsWith 4 With 4 –– 2xT1 cards per server, 149 2xT1 cards per server, 149 servers are neededservers are needed149 servers x $2000 = $298K149 servers x $2000 = $298KCost for Hardware DSP PSTN GW Cost for Hardware DSP PSTN GW $2,683K, Software PSTN GW $819K$2,683K, Software PSTN GW $819K

Dedicated Platform CostDedicated Platform Cost

Cisco AS5850Cisco AS5850Good port density with 5 CT3’s (190 T1’s), Good port density with 5 CT3’s (190 T1’s), 3360 channels in one fully loaded chassis3360 channels in one fully loaded chassisLowest cost found $175KLowest cost found $175KCalculation come to $52/port Calculation come to $52/port ($175K/3360)($175K/3360)28,572 trunks require 8.5 AS5850’s28,572 trunks require 8.5 AS5850’sCost for this solution $1,513KCost for this solution $1,513K

Dedicated DSP vs Software DSP

$2,384

$298

$2,682

$224

$596$820

$1,513

$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

Interface Card Cost Server Cost Total Cost

Hardware

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Dedicated DSP Chip Software DSP Purpose Built

Rack Cost and SpaceRack Cost and Space

8 racks required for software PSTN GW8 racks required for software PSTN GW4 racks required for hardware DSP4 racks required for hardware DSP3 racks for AS5850 platform3 racks for AS5850 platformRack kits ~$1000Rack kits ~$1000Space availability more critical than cost of Space availability more critical than cost of rack hardwarerack hardware

Power CostPower Cost

Software DSP, 298 servers @ 300 Watts Software DSP, 298 servers @ 300 Watts per server = 89.4KWper server = 89.4KWHardware DSP, 149 servers @ 300 Watts Hardware DSP, 149 servers @ 300 Watts per server = 44.7KWper server = 44.7KW9 Cisco AS5850’s @ 2.4KW per unit = 9 Cisco AS5850’s @ 2.4KW per unit = 21.6KW21.6KWAverage cost per KW = $4,300Average cost per KW = $4,300Software $390K, Hardware $190K, Cisco Software $390K, Hardware $190K, Cisco AS5850’s $130KAS5850’s $130K

Power Cost

$390

$195

$130

$0$50

$100$150$200$250$300$350$400$450

Software DSP, 298 Servers Dedicated DSP Chip, 149Servers

Purpose Built, 9 CiscoAS5850's

AC Power Plant

In T

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Codec CostCodec Cost

Codec g.711 $0, high bandwidth 64KBCodec g.711 $0, high bandwidth 64KBCodec g.729 $10, low bandwidth 8KBCodec g.729 $10, low bandwidth 8KBUsing g.729 codec in this exercise drives Using g.729 codec in this exercise drives up cost of software DSP solution by up cost of software DSP solution by adding $285,720adding $285,720Ultimately the network architecture will Ultimately the network architecture will determine codec usagedetermine codec usageAlso codec usage can change as Also codec usage can change as requirements dictaterequirements dictate

Cost Includes Interface Cards, Servers, Racks and Power

$1,218$1,503

$2,881

$1,643

$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

$3,500

Software DSPSolution

Software DSPSolution with g.729

codec

Dedicated DSPSoulution

Cisco AS5850Solution

VoIP Service for 28,572 PSTN Trunks

In M

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Exercise ConclusionExercise Conclusion

Cost exercise intended to show potential Cost exercise intended to show potential cost differential between two methods of cost differential between two methods of converting analog voice to packet voiceconverting analog voice to packet voice(Voice quality note) When implemented (Voice quality note) When implemented properly, there is no discernable properly, there is no discernable difference between the two methodsdifference between the two methods

Architecture and IntegrationArchitecture and Integration

Large deployments scale better when Large deployments scale better when hardware platforms are separated by hardware platforms are separated by functionalityfunctionality

Voice MailVoice MailPSTN GatewayPSTN GatewayApplicationsApplicationsCall ConferenceCall ConferenceCustomer AggregationCustomer AggregationDial Plan RoutingDial Plan Routing

PSTN GatewayPSTN Gateway

Asterisk can be configured to perform Asterisk can be configured to perform PSTN GW functions to create a virtual PSTN GW functions to create a virtual VoIP channel per T1 channelVoIP channel per T1 channelIn an existing Carrier environment, PSTN In an existing Carrier environment, PSTN traffic through a Class 5 switchtraffic through a Class 5 switchThree methodsThree methods

T1 PRIT1 PRIT1 GR303T1 GR303T1 DedicatedT1 Dedicated

PSTN Gateway with PRI’sPSTN Gateway with PRI’s

Great way to efficiently use trunk capacityGreat way to efficiently use trunk capacityCan oversubscribe T1 links with numbersCan oversubscribe T1 links with numbersBundling multiple PRI’s gives fault Bundling multiple PRI’s gives fault protectionprotectionProven technologyProven technologyProvisioning Asterisk can be complexProvisioning Asterisk can be complexDynamic nature of PRI’s can add undue Dynamic nature of PRI’s can add undue provisioning strains with data basing provisioning strains with data basing functionsfunctions

PSTN Gateway with GR303PSTN Gateway with GR303

Newer protocol, also takes advantage of Newer protocol, also takes advantage of over subscribing T1 with numbersover subscribing T1 with numbersBundling multiple T1’s gives fault Bundling multiple T1’s gives fault protectionprotectionGR303 Aggregator can be used in GR303 Aggregator can be used in between Class 5 switch and Asterisk GW between Class 5 switch and Asterisk GW to enhance static soft switch provisioningto enhance static soft switch provisioning

VoIP GW Provisioning ModelVoIP GW Provisioning Model

New services require new processes for adds, New services require new processes for adds, moves and changesmoves and changesAutomation determines level of human and Automation determines level of human and machine involvement with provisioningmachine involvement with provisioningAdding VoIP services into existing business Adding VoIP services into existing business processes can be complexprocesses can be complex

Setup I/O database picksSetup I/O database picksCorrelating VoIP extensions to telephone #’sCorrelating VoIP extensions to telephone #’sConfiguring features per customerConfiguring features per customerCreating dial plan routingCreating dial plan routing

VoIP GW Provisioning Model (cont)VoIP GW Provisioning Model (cont)

Using static VoIP connection channels to Using static VoIP connection channels to PSTN trunks provides minimal impact to PSTN trunks provides minimal impact to daily provisioning tasksdaily provisioning tasksWhen VoIP channels are bonded to Class When VoIP channels are bonded to Class 5 switch channels, existing provisioning 5 switch channels, existing provisioning model can facilitate customer turnmodel can facilitate customer turn--upupThe VoIP platform can be preThe VoIP platform can be pre--provisioned provisioned and associated statically to existing and associated statically to existing databasesdatabases

VoIP GW Provisioning Model (cont)VoIP GW Provisioning Model (cont)

Conceptually, a static soft switch platform Conceptually, a static soft switch platform can be achieved throughout all VoIP can be achieved throughout all VoIP functions and applicationsfunctions and applicationsCPE can be preCPE can be pre--assigned to customer assigned to customer aggregation channelsaggregation channelsCustomer Aggregation channels can be Customer Aggregation channels can be prepre--routed to PSTN GW channelsrouted to PSTN GW channelsPrePre--assigned Voice Mail accounts can be assigned Voice Mail accounts can be associated with each customer channelassociated with each customer channel

Application ServersApplication Servers

Asterisk is modular software like LinuxAsterisk is modular software like LinuxAsterisk can be setup as monolithic Asterisk can be setup as monolithic application server for specific taskapplication server for specific taskThis allows server farms to grow as This allows server farms to grow as needed prescribed by the customer or needed prescribed by the customer or function load per applicationfunction load per applicationPSTN GW server can handle 96 channels PSTN GW server can handle 96 channels where the same server may handle 500 where the same server may handle 500 Voice Mail channelsVoice Mail channels

Customer Aggregation ServersCustomer Aggregation Servers

Setup aggregation servers for protocol type, SIP, Setup aggregation servers for protocol type, SIP, IAX, MGCP, H323IAX, MGCP, H323Firewall each server according to protocolFirewall each server according to protocolStatically map each CPE channel to a Customer Statically map each CPE channel to a Customer aggregation channel on serveraggregation channel on serverSegment Customer IVR or ACD applications on Segment Customer IVR or ACD applications on the same serverthe same serverAggregate multiple Customer groups with Aggregate multiple Customer groups with different dial plans and call handling routinesdifferent dial plans and call handling routines

Dial Plan ServersDial Plan Servers

Provides the core switching unit for the VoIP Provides the core switching unit for the VoIP platform handling all call routingplatform handling all call routingUses IAX protocol between PSTN GW, Uses IAX protocol between PSTN GW, Customer Aggregation and Application serversCustomer Aggregation and Application serversDrops out of call path once transfer is madeDrops out of call path once transfer is madeDual server, hardware and software fault Dual server, hardware and software fault redundant, self diagnosis for fail over and load redundant, self diagnosis for fail over and load sharingsharingCan reload dial plan without restarting serviceCan reload dial plan without restarting service

Operations and MaintenanceOperations and Maintenance

2 maybe 3 VoIP specialist as server 2 maybe 3 VoIP specialist as server quantity increasesquantity increasesCreate dial plan consistent with best Create dial plan consistent with best practices of provisioning within host Telcopractices of provisioning within host TelcoKeep track of software updates that add Keep track of software updates that add features or fix bugsfeatures or fix bugsTrack server usage and resource loadingTrack server usage and resource loadingPlan for increasing capacity when neededPlan for increasing capacity when needed

Software and Hardware Software and Hardware ImprovementsImprovements

Future plans, look for increase port density Future plans, look for increase port density for interface cards, i.e. DS3for interface cards, i.e. DS3Look for added protocols, i.e. SS7Look for added protocols, i.e. SS7Look for VoIP Hardware Vendors adding Look for VoIP Hardware Vendors adding IAX protocolIAX protocolLook for integration with presence Look for integration with presence systems, i.e. Jabber, AIM, MSNsystems, i.e. Jabber, AIM, MSN

ConclusionConclusion

State of technology has never been or will State of technology has never been or will ever be staticever be staticDon’t rely on equipment Vendors to add Don’t rely on equipment Vendors to add new products to your service portfolionew products to your service portfolioTelco’s pronounce themselves as Telco’s pronounce themselves as technology companies, but sell services technology companies, but sell services built by Vendorsbuilt by VendorsEmbrace the ability to build on a stable Embrace the ability to build on a stable and robust VoIP platform, Asteriskand robust VoIP platform, Asterisk

Conclusion (cont)Conclusion (cont)

Asterisk is a project that delivers into the Asterisk is a project that delivers into the hands of the novice and experienced alike, hands of the novice and experienced alike, a platform for developing telecom a platform for developing telecom applications that bridge the gap between applications that bridge the gap between the existing TDM technology and future the existing TDM technology and future VoIP technology. Asterisk is well suited for VoIP technology. Asterisk is well suited for small scale customers and if deployed small scale customers and if deployed properly, robust enough to deliver VoIP properly, robust enough to deliver VoIP services to a very, very large customer services to a very, very large customer base. base.