Elastic Load Balancing automatically distributes incoming application traffic across multiple Amazon EC2 instances for fault tolerance and load distribution. In this session, we go into detail about Elastic Load Balancing's configuration and day-to-day management, as well as its use in conjunction with Auto Scaling. We explain how to make decisions about the service and share best practices and useful tips for success.

1. © 2016, Amazon Web Services, Inc. or its Affiliates. All rights reserved.
Mariano Vecchioli – AWS Technical Account Manager
Ben Doyle, Senior Infrastructure Engineer, Ensighten
July 2016
Deep Dive on
Elastic Load Balancing

2. Elastic Load Balancing
Security Scalability Availability

3. Security

4. SSL/TLS SSL Security Policies
• Same-day mitigation for POODLE
• Same-day mitigation for LogJam
• Same-day mitigation for Heartbleed
• RC4 removed in advance of ratings and compliance
changes

5. SSL/TLS Management
https://github.com/awslabs/s2n

6. SSL/TLS Management

7. SSL/TLS Cipher Suites
• Always prefer perfect forward secrecy.
• Prefer AES over 3DES over RC4.
• Prefer GCM over CBC + HMAC.
• Compare against billions of connections from real-world
clients.

8. SSL/TLS Cipher Suites
• Legacy clients can cause compatibility issues
• Old firmware in embedded systems
• TVs, controllers, web scrapers…
• ELB defaults strike a balance
• Access log gap analysis
• We recommend ELBSecurityPolicy-2015-05

9. Elastic Load Balancing
2015-05-13T23:39:43.945958Z my-loadbalancer
192.168.131.39:2817 10.0.0.1:80 0.000086 0.001048
0.001337 200 200 0 57 "GET
https://www.example.com:443/ HTTP/1.1” "curl/7.38.0"
DHE-RSA-AES128-SHA TLSv1.2
S3

10. Elastic Load Balancing
2015-05-13T23:39:43.945958Z my-loadbalancer
192.168.131.39:2817 10.0.0.1:80 0.000086 0.001048
0.001337 200 200 0 57 "GET
https://www.example.com:443/ HTTP/1.1” "curl/7.38.0"
DHE-RSA-AES128-SHA TLSv1.2

11. Elastic Load Balancing
2015-05-13T23:39:43.945958Z my-loadbalancer
192.168.131.39:2817 10.0.0.1:80 0.000086 0.001048
0.001337 200 200 0 57 "GET
https://www.example.com:443/ HTTP/1.1” "curl/7.38.0"
DHE-RSA-AES128-SHA TLSv1.2

12. ELB and Security Compartmentalization
Public subnet
Private subnet

13. ELB and Security Compartmentalization
Public subnet
Private subnet

14. ELB and Security Compartmentalization
Public subnet
Private subnet

15. ELB and Security Compartmentalization
Public subnet
Private subnet

16. ELB and Security Compartmentalization
Public subnet
Private subnet

17. ELB and Security Compartmentalization
Public subnet
Private subnet

18. Threat Modeling

19. Scalability

20. Scalability
Latency =
Load / Throughput

21. Scalability
Memory Latency

22. Scalability
Caching and cache misses

23. Scalability
Processing time
Count

24. Scalability
GET / HTTP/1.1
GET /monthly_report/ HTTP/1.1

25. Scalability
Processing time
Count

26. Scalability
Wait time
Count

27. Scalability

28. Scalability
Wait time
Count
Weighed round robin
Single server

29. Scalability

30. Scalability
Wait time
Count
Weighed round robin
Single server
Least connections

31. Scalability
Wait time
Count
Beware of
blackholing
traffic
Weighed round robin
Single server
Least connections

32. ELB’s own scaling is a mix of pre-emptive, based
on the instance capacity you add, and reactive,
based on the load you receive.

33. CloudWatch and Auto Scaling
All load balancer metrics can be used for Auto Scaling.
Allow you to scale dynamically based on the load
balancers' view of the application.
Important to consider all metrics when using
Auto Scaling; may not be aware of resource
contention on another metric.
You may be at peak multiple times a day.

34. 13 CloudWatch metrics provided for each load
balancer.
Provide detailed insight into the health of the load
balancer and application stack.
CloudWatch alarms can be configured to notify or
take action, in case any metric goes outside of the
acceptable range.
All metrics provided at 1-minute granularity.
AmazonCloudWatch metrics

35. Latency
Measures the time elapsed in seconds after the request leaves the load
balancer until the response is received.
Test by sending requests to the back-end instance from another instance.
Using minimum, average, and maximum, CloudWatch
stats provide upper and lower bounds for latency.
Debug individual requests using access logs.

36. SurgeQueue and Spillovers
Count of the number of requests that could not be sent to back-end
instances.
Queue up to 1,024 requests per load balancer
node, after which 503 errors will be returned.
Often caused by not being able to open
connections to the back-end instance.
Normally a sign of an underscaled application.

37. • timestamp
• elb name
• client:port
• backend:port
• request_processing_time
• backend_processing_time
• response_processing_time
• elb_status_code
• backend_state_code
• received_bytes
• sent_bytes
• “request”
• “User-Agent”
• Ciphersuite
• SSL/TLS protocol version
Access Logs
2015-05-13T23:39:43.945958Z my-loadbalancer 192.168.131.39:2817
10.0.0.1:80 0.000086 0.001048 0.001337 200 200 0 57 "GET
https://www.example.com:443/ HTTP/1.1” "curl/7.38.0" DHE-RSA-
AES128-SHA TLSv1.2

38. Global Scalability
ELB integrates with Amazon Route 53 latency–based routing and geo-
based routing.
Useful for applications where latency is critical.
Online advertising bidding.
Trading 53

39. Availability

40. Ben Doyle
Senior Infrastructure Engineer
Digital analytics company with 2 types of products:
- Data collection and analysis of web traffic
- Website content (tag) management
Multiple global platforms for both

41. Seamless and graceful
replacement of instances
with no downtime

42. Health Checks
ELB
EC2
instance
EC2
instance
EC2
instance

43. Health Checks
Support for TCP and HTTP health checks.
Customize frequency and failure thresholds.
Must return a 200 response.
Think hard about health check “depth”.

44. Idle timeouts allow for connections to be
closed by the load balancer when no
longer in use.

45. Length of time that an idle connection should be kept open
For both client and back-endconnections
Defaults to 60 seconds but can be set between 1 and 3,600
seconds
Timeouts should decrease as you go
up the stack
Idle Timeouts

46. 15s
3s
3s
ELB
15s
EC2
instances
Amazon S3
Amazon RDS
Amazon SWF
3s
9s
Idle Timeouts

47. Multiple AvailabilityZones
VPC
EC2
instanceELB
ELB
EC2
instance
us-west-1aus-west-1b
Amazon
Route 53

48. Protected by Route 53 Health Checks
All load balancers scaled to handle the
loss of a singleAvailability Zone.
Amazon Route 53 health checks shift
traffic away from the failed Availability
Zone.
Completed within 150 seconds.
No other external or control plane
dependencies.

49. Health checkers and edge locations
perform the same volume of activity,
whether endpoints are healthy or
unhealthy.
Constant work
time
System activity
Time to react
When nothing is failing, the
volume of API calls is zero. When
failure occurs, the volume of API
calls spikes.
time
System activity
Time to react
Work on failure

50. Always associate two
or more subnets in
different zones with
the load balancer

51. Using multiple Availability Zones
does bring a few challenges

52. Requestcount
Time
Traffic Imbalances

53. DNS Caching and Spreading
DNS TTLs are generally honored.
But sometimes there simply are not enough DNS servers
to spread load around fairly.
Mobile networks typically have a dozen or so top-level
resolvers.
Enterprise networks may have as few as one.

54. Multiple AvailabilityZones
VPC
EC2
instanceELB
ELB
EC2
instance
us-west-1aus-west-1b
Amazon
Route 53

55. Multiple AvailabilityZones
EC2
instanceELB
ELB
us-west-1aus-west-1b
Amazon
Route 53
VPC

56. Requestcount
Time
Traffic Imbalances
Cross-zone enabled

57. Load balancer absorbs impact of DNS caching.
Eliminates imbalances in back-end instance utilization.
Requests distributedevenly across multiple
Availability Zones.
Check connection limits before enabling.
No additional bandwidth chargefor
cross-zonetraffic.
Cross-zone Load Balancing

58. Integrated with AWS CloudFormation,AWS OpsWorks,
AWS Elastic Beanstalk,Amazon ECS,AmazonAPI Gateway,
and Asgard.
Load balancers are a common gateway for blue/green
deployments.
Load balancers can be managed
programmatically for immutable
Deployments.
ELB and DevOps

59. Recap
Fully Managed SSL/TLS Stack
AWS Certificate Manager
Compartmentalisation
CloudWatch Metrics
Access Logs
Global Scalability
Minimal Downtime
Route53 Health Checks
Cross-zone Load Balancing

60. Please remember to rate this
session under My Agenda on
awssummit.london

61. Mariano Vecchioli
AWS Technical Account Manager
mrv@amazon.com
vekiar@
Ben Doyle
Senior Infrastructure Engineer
ben.doyle@ensighten.com
Ben__Doyle