Customers like Twilio, AudioCodes, and Vonage power their voice, video and messaging services using AWS's global infrastructure. In this session, we walk through the core AWS features and partner products that enable carrier-grade Voice-over-IP (VoIP), WebRTC, and IP Multimedia Subsystems (IMS) solutions. You'll walk away with best practices and lessons learned from our customers' experience. We address the requirements for low latency, high availability, and scalability, critical to communication workloads. To do so, we use a combination of advanced Amazon EC2 networking, Auto Scaling, CloudWatch, Elastic Load Balancing, Route 53, Direct Connect, and AWS Marketplace–provided options.

1. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
AWS re:INVENT
S h o m a C h a k r a v a r t y | G l o b a l T e l e c o m L e a d
A h m a d R . K h a n | S r . S o l u t i o n s A r c h i t e c t
Always Online: Real-Time
Communications on AWS
T L C 3 0 1
N o v e m b e r 2 7 , 2 0 1 7

2. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Topics We Will Cover
• Brief overview of real-time communications (RTC)
• Fundamental AWS capabilities as building blocks for SIP
and WebRTC-based solutions
• Scalability, high availability, and elasticity with Auto
Scaling
• Application enrichment
• Best practices from the field

3. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Brief Overview of Real-Time
Communications (RTC)—Use Cases,
Technologies, and Components

4. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Reflection: Two Fundamental Developments in
Real-Time Communications
• SIP:
– Standard protocol for IP-based streaming multimedia services since 2000
– Provides signaling and call setup protocol for IP-based communications
– Aims to support the call processing functions and features present in the Public Switched
Telephone Network (PSTN)
• WebRTC:
– Released by Google in 2011 as an open source project for browser-based real-time
communication
– Provides an API that enables real-time communication over peer-to-peer connections
– Enables rich real-time applications such as video conferencing, file transfer, chat, and
desktop sharing
– Being standardized by the World Wide Web Consortium (W3C) and the Internet
Engineering Task Force (IETF)

5. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Contemporary RTC Use Cases
• Voice, video, chat, and social
• Collaboration: conferencing, desktop sharing, document updates
• IVR applications: call center, customer service, self-serve, and so on
• Gaming
• Real-time content, data feeds, and crowd-sourcing apps
• Contextual Interactions: embedded chat, omni-channel marketing,
chatbots, and so on
• Machine-to-machine, person-to-machine (with IoT, personal assistants)
• Real-time digital experiences
**IETF published RFC 7478 in 2015 capturing typical WebRTC use cases

6. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Enabling RTC: Typical Architectural Components
Internet SBC
SIP
Redirect
Registrar
DB PBX or Media
Servers
(Conferencing,
Video, Media-mixing)
Registrar that stores Active
User Sessions and Location
Optional: May be used to
redirect/reinvite for Routing
- SIP Proxy
- Security
- Mediation for
Billing
- Media GW-
Device and
Codec Support
- NAT traversal
Performs PBX, Media
Server Functionality
Provides Framework
for Telephony Apps
PSTN GW
PSTN
network
WebRTC GW

7. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
SIP
RedirectSIP
Redirect
PBX
Media
Servers
PBX
Media
Servers
Scope: Real-Time Communications on AWS
Internet SBC
SIP
Redirect
Registrar
DB PBX or
Media
Servers
Registrar that stores Active
User Sessions and Location
Optional: May be used to
redirect/reinvite for Routing
- SIP Proxy
- Security
- Mediation for
Billing
- Media GW-
Device and
Codec Support
- NAT traversal
Performs PBX, Media
Server Functionality
Provides Framework
for Telephony Apps
PSTN GW
PSTN
network
WebRTC GW
SBC
Mechanisms for High Availability, Scalability, Elasticity, and Global Outreach

8. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Fundamental AWS Capabilities as
Building Blocks for SIP and WebRTC-
Based Solutions

9. Building Blocks for a Basic RTC Topology on AWS
Amazon EC2
• Multiple OS
• EIP, secondary IP
addresses, multiple
ENIs
• Security groups
• Source-destination
check
Amazon VPC
• Subnets
• Route tables
• NACLs
• Internet gateway
WebRTC GW/
SBC
VPC
Availability Zone 1
WebRTC GW/
SBC PBX
Public Subnet
Public Subnet
Private Subnet
AWS Region
PBX
LB
LB
PBX
PBX
Availability Zone 2
Private Subnet
HA
HA
EIP
EIP
eth0, eth0:1
eth1

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Amazon EC2 Performance: SR -IOV Support and
Elastic Network Adapter
• SR-IOV is a method of device
virtualization that provides higher I/O
performance and lower CPU utilization
• It is supported on Amazon EC2
instances C3, C4, D2, I2, R3, and M4
(excluding m4.16xlarge) with
network speeds of up to 10 Gbps
• The Elastic Network Adapter (ENA)
supports network speeds of up to 25
Gbps for supported instance types C5, F1,
G3, I3, P2, R4, X1, and m4.16xlarge
instances
• ENA is supported in Amazon Linux
out of the box, but other Linux and
Windows drivers are available
• DPDK driver for ENA is also
available
• To support a high volume of
concurrent sessions and PPS,
Amazon EC2 instances can benefit
from:
• SR-IOV
•Intel’s DPDK for fast-forwarding of
media packets
•Elastic Network Adapter
•Placement groups when using a
clustered configuration; for example,
HA cluster, for clusters handling
media transcoding and compression,
and so on

11. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
AWS Direct Connect
• Dedicated, private connection into AWS
• Create private (Amazon VPC) or public virtual interfaces
to AWS
• Reduced data-out rates
• Consistent network performance
• Option for redundant connections
• Multiple AWS accounts can share a connection
• Uses BGP to exchange routing information over a VLAN

12. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Connectivity with Direct Connect: Dedicated
Bandwidth, Resilient, and Diverse Paths
AZ
AZ
AZ AZ AZ
Transit
Transit
DX Location 1
DX Location 2
AWS Direct
Connect Routers
AWS Direct
Connect Routers
Enterprise1
Enterprise
N
MPLS
MPLS
DX Partner
DX Partner

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High Availability and Scalability
Compute: Amazon EC2, AWS Lambda, Amazon ECS, Auto Scaling
Networking: Amazon VPC, AWS Direct Connect, Elastic Load Balancing,
Amazon Route 53

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High Availability for Stateful Instance Using
Floating IP Pattern and Amazon EC2 API
eu-west-1a
VPC
+ AWS provides EC2 API and
AMI Tools SDK
+ Monitoring script, Keepalived,
etc.
+ Private secondary IP
reassignment via EC2 API
+ Asterisk bind to correct
floating IP
+ Alias network interface on OS
for delivery of media
PBX Subnet
VIP
PBX
PBX
ec2-assign-private-ip-addresses -n MyENI_ID --secondary-private-ip-address MyVIP --allow-
reassignment --region MyRegion

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• Automatic resizing of compute clusters
• Define min/max pool sizes
• Amazon CloudWatch metrics drive scaling
• On-demand, spot instances, or
Amazon ECS
aws autoscaling create-auto-scaling-group
--auto-scaling-group-name MyGroup
--launch-configuration-name MyConfig
--min-size 4
--max-size 200
--availability-zones us-west-2c, us-west-2b
Auto Scaling
• Well-suited for burst
• Lifecycle hooks allow for
graceful shutdown; for example,
Asterisk allows for calls in
session to complete before
scale-in

16. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
SIP-Based RTC Scalability and HA
NLB
for TCP is
GA
4
RTC
GW/SBC
eu-west-1a
Media/PBX
eu-west-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
CloudWatch
RTC
GW/SBC
VIP
PBX
PBX
Media/PBX
VIP PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B
1. AWS Marketplace offers
load-balancing options
for SIP/UDP and
SIP/TCP
2. The floating IP design
pattern can be
implemented on EC2
3. CloudWatch Logs allow
for instance-hosted log
agent to gather custom
metrics. CloudWatch
events can be
configured to trigger
alarms and Lambda
functions.
4. NLB is GA with support
for layer four load-
balancing over TCP
Auto
Scaling

17. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
WebRTC Scalability and HA
1. Elastic Load Balancer
provides scalability and
HA
2. Auto Scaling groups can
use multiple launch
formations, support
scaling policies that can
track to a target metric,
and support scheduled
action
3. The Floating IP design
pattern can be
implemented on EC2
4. CloudWatch Logs allow
for instance-hosted log
agent to gather custom
metric. CloudWatch
events can be
configured to trigger
alarms and Lambda
functions.
RTC
GW/SBC
eu-west-1a
Media/PBX
eu-west-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
4Auto
Scaling
CloudWatch
RTC
GW/SBC
Auto
Scaling
VI
P
PBX
PBX
Media/PBX
VIP
PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B

18. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Inter-Region HA Using Amazon Route 53 for LBR
and DNS Failover
Route 53
Latency-based routing
Geo-fencing
Failover = TTL + (Interval * Threshold)
e.g. 60 + (10*3)
SIP-TLS
RTC
GW/SBC
eu-west-1a
Media/PBX
eu-west-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
4Auto
Scaling
CloudWatch
RTC
GW/SBC
Auto
Scaling
VIP
PBX
PBX
Media/PBX
VIP
PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B
RTC
GW/SBC
us-east-1a
Media/PBX
us-east-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
4Auto
Scaling
CloudWatch
RTC
GW/SBC
Auto
Scaling
VIP
PBX
PBX
Media/PBX
VIP
PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B

19. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Enhanced Inter -Region High Availability Using
Amazon Route 53 and Marketplace Anycast Solution
Route 53
• Reduced RTO with Datapath.io
Anycast solution
• Increased resiliency with Amazon
Route 53
• Global access with latency-based
routing to nearest region
RTC
GW/SBC
Us-East-1a
Media/PBX
Us-East-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
4Auto Scaling
CloudWatch
Spot
RTC
GW/SBC
Auto ScalingSpot
VIP
PBX
PBX
Media/PBX
VIP
PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B
GW
Anycast
Netwk-
Opt
Datapath
DataCenter
CGW
CGW
Site A
Site B
Site C
RTC
GW/SBC
eu-west-1a
Media/PBX
eu-west-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
4Auto
Scaling
CloudWatch
RTC
GW/SBC
Auto
Scaling
VIP
PBX
PBX
Media/PBX
VIP
PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B
RTC
GW/SBC
us-east-1a
Media/PBX
us-east-1b
VPC
Public Private
Public
1
VIP
PBX
PBX
2
3
4Auto
Scaling
CloudWatch
RTC
GW/SBC
Auto
Scaling
VIP
PBX
PBX
Media/PBX
VIP
PBX
PBX
VIP
PBX
PBX
Private
Subscriber Grp A
Subscriber Grp B

20. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Auto Scaling with Graceful Instance Termination
D e s i g n P a t t e r n : A u t o S c a l i n g L i f e c y c l e H o o k s , C l o u d W a t c h E v e n t s , a n d
A W S L a m b d a
Use case: during scale-in, stop media
server gracefully
• Auto Scaling scale-in policy
causes instance termination,
which invokes life-cycle hook
and registers a CloudWatch
Event
• Event is configured with a rule
to invoke a Lambda function
• Lambda function handler calls
EC2 SSM to Run Command
• Run Command script calls for
Asterisk to “stop gracefully”:
complete calls in progress and
then stop
CloudWatch
Events
Terminating instance
invokes Lifecycle Hook,
which registers an
Event, and triggers Rule
Lambda
function
instance instance
Auto Scaling Group
EC2
Systems Mgr
Run Command Script to “stop
Asterisk gracefully” is invoked
on Terminating EC2 Instance
Lambda asks EC2
SSM to Run
Command
Rule invokes
Lambda
Complete
Lifecycle
Hook
1
2 3
4
5

21. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Auto Scaling with Dynamic Updates to Route 53
D e s i g n P a t t e r n : A u t o S c a l i n g , C l o u d W a t c h E v e n t s , a n d A W S L a m b d a
Use case: during scale-out or in,
dynamically add/delete DNS
records to Route 53
• Auto Scaling scale-out
policy triggers CloudWatch
Events when instances
change state after launch
• Event is configured with a
rule to invoke a Lambda
function
• Lambda function handler
checks if state change is
from pending to “running,”
and then updates Route 53
to add DNS A records to
reflect new instances in
Auto Scaling cluster
• Alternatively use startup
and shutdown scripts
CloudWatch
Events
When newly launched
instance changes state, an
Event is registered, which
triggers Rule
Lambda
function
instance instance
Auto Scaling Group
Route 53
Lambda calls
Route 53 API to
add new DNS
records
Rule invokes
Lambda
1
2 3
Route 53 zone is now
updated with new
resource records

22. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
RTC: Application Enrichment

23. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
• Amazon Polly: text to speech
• Amazon Lex: conversational interfaces
• Alexa Voice Services
Application Enrichment

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Best Practices

25. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Creating a SIP Overlay

26. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Handling Backbone Issues
Amazon
Route 53
us-west-2 region
SBC
PBX /
SIP Proxy
us-east-1 region
SBC
us-west-1 region
SBC
PBX /
SIP Proxy
PBX /
SIP Proxy

27. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Demo: Handling Backbone Issues

28. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.

29. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Best Practices
• Create a SIP overlay

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Handling Instance and AZ Issues
Availability Zone #1
Amazon
Route 53
PSTNus-east-1 region
SBC
Availability Zone #1
us-west-2 region
SBC
Availability Zone #2
SBC
Availability Zone #2
SBC
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy

31. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Amazon Route 53 SRV Records
Availability Zone #1
us-east-1 region
SBC pbx1
SBC
Availability Zone #2
pbx2
A: pbx1.example.com 1.1.1.1
A: pbx2.example.com 1.1.2.1
SRV: _sip._udp.east.example.com
1 10 4060 pbx1.example.com
1 10 4060 pbx2.example.com
Amazon
Route 53
User ID: 200
Password: xxxx
Domain: east.example.com

32. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
PSTN/ITSP Trunk
Amazon
Route 53
PSTN
us-east-1 region (AZ1)
SBC
us-west-2 region
SBC
us-east-1 region (AZ2)
SBC
ITSP
Twilio Elastic SIP
Trunking
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy

33. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Demo: SIP Trunking Using Twilio
Twilio Elastic SIP
Trunking

34. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.

35. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Best Practices
• Create a SIP overlay
• Use multiple Availability Zones (AZs) and use DNS to load balance/fail over

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AZ Affinity
Availability Zone #1
Amazon
Route 53
PSTN
us-east-1 region
SBC
Availability Zone #1
us-west-2 region
SBC
Availability Zone #2
SBC
Availability Zone #2
100% of active calls
are lost
SBC
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy

37. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
AZ Affinity
Availability Zone #1
Amazon
Route 53
PSTN
us-east-1 region
SBC
Availability Zone #1
us-west-2 region
SBC
Availability Zone #2
SBC
Availability Zone #2
PBX
At most, 50% of
active calls are lost
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy
PBX /
SIP Proxy

38. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Best Practices
• Create a SIP overlay
• Use multiple Availability Zones (AZs) and use DNS to load balance/fail over
• Keep media/signaling within one AZ in a region

39. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
SIP Monitoring
Tools:
• SIPp
• iperf
Amazon
CloudWatch
SIPp

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Demo: SIP Monitoring

41. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Best Practices
• Create a SIP overlay
• Use multiple Availability Zones (AZs) and use DNS to load balance/fail over
• Keep media/signaling within one AZ in a region
• Setup real-time full-mesh monitoring (SIPp)
• Key Metrics:
• Successful calls
• SIP retransmits
• Export metrics to a monitoring solution (CloudWatch)
• Create alarms and take remediation actions like changing SIP routing

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Supported instance type
C3, C4, D2, I2, R3, and M4 (excluding m4.16xlarge)
instances use the Intel 82599 VF interface for
enhanced networking
Bandwidth
1 or 10 Gbps
Supported instance types
F1, G3, I3, P2, R4, X1, and m4.16xlarge instances use
the Elastic Network Adapter for enhanced
networking
Bandwidth
25 Gbps
E l a s t i c N e t w o r k A d a p t e r
( E N A )
I n t e l 8 2 5 9 9 V i r t u a l
F u n c t i o n ( V F ) i n t e r f a c e
Using Network Optimized Instances

43. © 2017, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Best Practices
• Create a SIP overlay
• Use multiple Availability Zones (AZs) and use DNS to load balance/fail over
• Keep media/signaling within one AZ in a region
• Setup real-time full-mesh monitoring (SIPp)
• Key Metrics:
• Successful Calls
• SIP retransmits
• Export metrics to a monitoring solution (CloudWatch)
• Create alarms and take remediation actions like changing SIP routing
• Use the enhanced networking Amazon EC2 instance types

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Q&A

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Thank you!
T L C 3 0 1 — A l w a y s O n l i n e : R e a l T i m e C o m m u n i c a t i o n s o n A W S