Leveraging Asterisk to Deliver Large Scale VoIP Services in a Carrier Environment. JR Richardson

Transcription

1 Leveraging Asterisk to Deliver Large Scale VoIP Services in a Carrier Environment JR Richardson

2 Early VoIP Environment Telecom Act of 1996, mass competition, Telco's needed value add features and capabilities, VoIP held great potential VoIP services very immature and costly Hardware VoIP solutions expensive with few features compared to POTS Software VoIP existed but PC platform processor speeds too low for mass scale

3 What is Asterisk? Open Source Hybrid TDM and packet voice PBX and IVR platform Runs on general computing platform Analog and Digital telephony interfaces Supports SIP, H323, MGCP, SCCP and IAX2 Dial Plan scripting bound only by imagination of administrator

4 Hot Debate: Hardware or Software DSP? Digital Signal Processing has been a barrier to low cost VoIP services Hardware solutions are high cost in nature Software DSP technology has been around for years but PC performance low PC performance has increased enough to warrant investigation into large scale soft switch solutions

5 Hardware vs. Software DSP Exercise Critical planning event for VoIP deployment, calculate PSTN access, TDM to Packet Voice transcoding Large Scale 200K line side extensions Trunk ratio 7:1 28,571 DSP channels required

6 Hardware DSP Cost Lowest price Dialogic hardware, 2xT1 PCI card, $7,999 Assuming volume 50%, $4000/2xT1 card achievable Calculation comes to $83/port ($4000/48) 28,571 trunks / 24 ports per T1 = 1191 T1 s needed / 2 T1 s per card = 596 cards 596 cards x $4000 = $2,384K

7 Software DSP Cost Digium 4xT1 cards list $1500 Assuming volume 50%, $750/4xT1 card achievable (is Mark Spencer watching?) Calculation comes to $7.80/port ($750/96) 28,571 trunks / 24 ports per T1 = 1191 T1 s needed / 4 T1 s per card = 298 cards 298 cards x $750 = $223,500 1/10 th the cost of hardware DSP cards

8 Processor Loading Sending transcoding function to central CPU has trade offs, processor loading To utilize all 96 channels on 4xT1 card, the server must be robust, driving up cost Dual Zeon 2.8GHz, 1 Gig RAM, SCSI HD With strong vendor relations, can achieve server $2000 With 1-4xT1 Digium card per server, 298 are servers needed

9 Processor Loading (cont) 298 servers x $2000 = $596K With hardware DSP cards, same server could easily handle 4 cards With 4 2xT1 cards per server, 149 servers are needed 149 servers x $2000 = $298K Cost for Hardware DSP PSTN GW $2,683K, Software PSTN GW $819K

10 Dedicated Platform Cost Cisco AS5850 Good port density with 5 CT3 s (190 T1 s), 3360 channels in one fully loaded chassis Lowest cost found $175K Calculation come to $52/port ($175K/3360) 28,572 trunks require 8.5 AS5850 s Cost for this solution $1,513K

11 Dedicated DSP vs Software DSP $3,000 $2,500 $2,384 $2,682 In M illions $2,000 $1,500 $1,000 $500 $224 $298 $596 $820 $1,513 $0 Interface Card Cost Server Cost Total Cost Hardware Dedicated DSP Chip Software DSP Purpose Built

12 Rack Cost and Space 8 racks required for software PSTN GW 4 racks required for hardware DSP 3 racks for AS5850 platform Rack kits ~$1000 Space availability more critical than cost of rack hardware

13 Power Cost Software DSP, Watts per server = 89.4KW Hardware DSP, Watts per server = 44.7KW 9 Cisco AS KW per unit = 21.6KW Average cost per KW = $4,300 Software $390K, Hardware $190K, Cisco AS5850 s $130K

14 Power Cost In Thousands $450 $400 $350 $300 $250 $200 $150 $100 $50 $0 $390 $195 Software DSP, 298 Servers Dedicated DSP Chip, 149 Servers AC Power Plant $130 Purpose Built, 9 Cisco AS5850's

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

16 Cost Includes Interface Cards, Servers, Racks and Power $3,500 $3,000 $2,881 $2,500 In M illio n s $2,000 $1,500 $1,000 $1,218 $1,503 $1,643 $500 $0 Software DSP Solution Software DSP Solution with g.729 codec Dedicated DSP Soulution Cisco AS5850 Solution VoIP Service for 28,572 PSTN Trunks

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

18 Architecture and Integration Large deployments scale better when hardware platforms are separated by functionality Voice Mail PSTN Gateway Applications Call Conference Customer Aggregation Dial Plan Routing

19 PSTN Gateway Asterisk can be configured to perform PSTN GW functions to create a virtual VoIP channel per T1 channel In an existing Carrier environment, PSTN traffic through a Class 5 switch Three methods T1 PRI T1 GR303 T1 Dedicated

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21 PSTN Gateway with PRI s Great way to efficiently use trunk capacity Can oversubscribe T1 links with numbers Bundling multiple PRI s gives fault protection Proven technology Provisioning Asterisk can be complex Dynamic nature of PRI s can add undue provisioning strains with data basing functions

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23 PSTN Gateway with GR303 Newer protocol, also takes advantage of over subscribing T1 with numbers Bundling multiple T1 s gives fault protection GR303 Aggregator can be used in between Class 5 switch and Asterisk GW to enhance static soft switch provisioning

24 VoIP GW Provisioning Model New services require new processes for adds, moves and changes Automation determines level of human and machine involvement with provisioning Adding VoIP services into existing business processes can be complex Setup I/O database picks Correlating VoIP extensions to telephone # s Configuring features per customer Creating dial plan routing

25 VoIP GW Provisioning Model (cont) Using static VoIP connection channels to PSTN trunks provides minimal impact to daily provisioning tasks When VoIP channels are bonded to Class 5 switch channels, existing provisioning model can facilitate customer turn-up up The VoIP platform can be pre-provisioned provisioned and associated statically to existing databases

26 VoIP GW Provisioning Model (cont) Conceptually, a static soft switch platform can be achieved throughout all VoIP functions and applications CPE can be pre-assigned to customer aggregation channels Customer Aggregation channels can be pre-routed routed to PSTN GW channels Pre-assigned Voice Mail accounts can be associated with each customer channel

27 Application Servers Asterisk is modular software like Linux Asterisk can be setup as monolithic application server for specific task This allows server farms to grow as needed prescribed by the customer or function load per application PSTN GW server can handle 96 channels where the same server may handle 500 Voice Mail channels

28 Customer Aggregation Servers Setup aggregation servers for protocol type, SIP, IAX, MGCP, H323 Firewall each server according to protocol Statically map each CPE channel to a Customer aggregation channel on server Segment Customer IVR or ACD applications on the same server Aggregate multiple Customer groups with different dial plans and call handling routines

29 Dial Plan Servers Provides the core switching unit for the VoIP platform handling all call routing Uses IAX protocol between PSTN GW, Customer Aggregation and Application servers Drops out of call path once transfer is made Dual server, hardware and software fault redundant, self diagnosis for fail over and load sharing Can reload dial plan without restarting service

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31 Operations and Maintenance 2 maybe 3 VoIP specialist as server quantity increases Create dial plan consistent with best practices of provisioning within host Telco Keep track of software updates that add features or fix bugs Track server usage and resource loading Plan for increasing capacity when needed

32 Software and Hardware Improvements Future plans, look for increase port density for interface cards, i.e. DS3 Look for added protocols, i.e. SS7 Look for VoIP Hardware Vendors adding IAX protocol Look for integration with presence systems, i.e. Jabber, AIM, MSN

33 Conclusion State of technology has never been or will ever be static Don t rely on equipment Vendors to add new products to your service portfolio Telco s pronounce themselves as technology companies, but sell services built by Vendors Embrace the ability to build on a stable and robust VoIP platform, Asterisk

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