Global Infrastructure

A global application is an application deployed in multiple geographies
- Geographies in AWS could mean Regions and / or Edge Locations
Benefits:
- Decreased latency
  - Latency is time taken for a network packet to reach a server (Ex. takes time for a packet from Asia to reach the US)
  - Deploy applications closer to your users to decrease latency, improving experience
- Disaster recovery
  - If an AWS region goes down (earthquake, storms, power outage, politics, etc.), you can failover to another region to maintain application runtime
  - A disaster recovery plan is important to increase the availability of your application
- Attack protection
  - Distributed global infrastructure is harder to attack
Global AWS Infrastructure
- Regions: For deploying applications and infrastructure
- Availability Zones: Made of multiple data centres
- Edge Locations (Points of Presence): For content delivery as close as posible to users
- More information at https://infrastructure.aws/
Global applications in AWS
- Global DNS: Route 53
  - Good for routing users to the closest deployment with least latency
  - Good for disaster recovery strategies
- Global Content Delivery Network (CDN): CloudFront
  - Replicate part of your application to AWS Edge Locations to decrease latency
  - Cache common requests, improves user experience and decreases latency
- S3 Transfer Acceleration
  - Accelerate global uploads & downloads into Amazon S3
- AWS Global Accelerator
  - Improve global application availability and performance using the AWS global network

Route 53

Route 53 is a managed DNS (Domain Name System)
A DNS is a collection of rules and records which help clients understand how to reach a server through URLs
Most common records in AWS:
- www.google.com --> 12.34.56.78 == A record (IPv4)
- www.google.com --> 2001:0db8:85a3:0000:0000:8a2e:0370:7334 == AAAA IPv6
- search.google.com --> www.google.com == CNAME: hostname to hostname
- example.com --> AWS resource == Alias (ex. ELB, CloudFront, S3, RDS, etc.)
Routing Policies
- Simple Routing Policy
  - Web browser enter DNS and perform a query, gets and IP address
  - No health checks
- Weighted Routing Policy
  - Distribute traffic across multiple EC2 instances, assign weights to instances representing weight to distribute
  - Can use health checks
- Latency Routing Policy
  - Dynamically redirect the user to connect to a closer server based off their location, reducing latency
- Failover Routing Policy
  - DNS performs health check on a primary instance, if it fails then it will use a failover instance
  - A form of disastery recovery

CloudFront

CloudFront is a CDN (Content Delivery Network)
Improves read performance since content is cached at different edge locations
Users around the world will have a better experience
As of the course being published, there are 216 points of presence globally (edge locations)
Content being distributed globally enables DDoS protection, integration with Shield and AWS Web Application Firewall
Origins of CloudFront
- S3 bucket
  - For distributing files and caching them at the edge
  - Enhanced security with CloudFront Origin Access Control (OAC)
  - OAC is replacing Origin Access Identity (OAI)
  - CloudFront can be used as an ingress (to upload files to S3)
- Custom Origin (HTTP)
  - Application Load Balancer
  - EC2 instance
  - S3 website (must enable the bucket as a static S3 website)
  - Any HTTP backend as desired
CloudFront vs S3 Cross Region Replication
- CloudFront
  - Global edge network
  - Files are cached for a TTL for maybe a day
  - Great for static content that must be available everywhere
- S3 Cross Region Replication
  - Must be setup for each region you want replication to happen
  - Files are updated in near real-time
  - Read-only
  - Great for dynamic content that needs to be available at low latency in few regions
S3 Transfer Acceleration
- Increase transfer speed by transferring a file to an AWS edge location which forwards the data to the S3 bucket in the target region

AWS Global Accelerator

Global Accelerator is a network service for improving global application availability and performance using the AWS global network
Leverages the AWS internal network to optimise the route to your application (up to 60% improvement)
2 Anycast IP are created for your application and traffic is sent through edge locations
The edge locations send the traffic to your application
AWS Global Accelerator vs CloudFront
- Both use AWS global network and its edge locations around the world
- Both integrate with AWS Shield for DDoS protection
- CloudFront - Content Delivery Network
  - Improves performance for your cacheable content (ex. images and videos)
  - Content is served at the edge
- Global Accelerator
  - No caching, proxying packets at the edge to applications running in one or more AWS regions
  - Improves performance for a wide range of applications over TCP or UDP
  - Good for HTTP use cases requiring static IP addresses or deterministic, fast regional failover

AWS Outposts

AWS Outposts are "server racks", offering the same AWS infrastructure, services, APIs and tools to build your own applications on-premises similar to the cloud
A hybrid cloud consists of on-premises infrastructure alongside a cloud infrastructure
- Two ways of dealing with IT systems:
  - One for the AWS cloud (using AWS console, CLI and APIs)
  - One for their on-premises infrastructure
AWS will setup and manage Outposts Racks within your on-premises infrastructure and you can start leveraging AWS services on-premises
You are responsible for the Outposts Rack physical security
Benefits:
- Low latency access to on-premises systems
- Local data processing
- Data residency
- Easier migration from on-premises to the cloud
- Fully managed service
- Some services that work on Outposts:
  - EC2, EBS, S3, EKS, ECS, RDS, EMR

AWS Wavelength

Wavelength Zones are infrastructure deployments embedded within the telecommunications providers' data centres at the edge of 5G networks
Brings AWS services to the edge of 5G networks
- Ex. EC2, EBS, VPC, etc.
Ultra-low latency applications through 5G networks
Traffic doesn't leave the Communication Service Provider's (CSP) network
High-bandwidth and secure connection to the parent AWS Region
No additional charges or service agreements
Use cases:
- Smart Cities
- ML-assisted diagnostics
- Connected vehicles
- Interactive Live Video Streams
- AR/VR
- Real-time gaming

AWS Local Zones

AWS Local Zones is a type of infrastructure deployment that places selected AWS services closer to end users to run latency-sensitive applications

Services include AWS compute, storage, database and some other ones
Extend your VPC to more locations ("Extension of an AWS Region")
Compatible with EC2, RDS, ECS, EBS, ElastiCache, Direct Connect, etc.
Ex. AWS Region: N. Virginia (us-east-1) and AWS Local Zones: Boston, Chicago, Dallas, Houston, Miami, ...

Global Applications Architecture

Single Region, Single AZ
- Low availability, high global latency, easy to setup
Single Region, Multi AZ
- High availability, high global latency, not as easy to setup
Multi Region, Active-Passive
- Active-Passive: Two regions, each having one or multiple AZ. In one region, EC2 instances / application are active (read / write) and the ones in the other region are passive (read-only)
- High global write latency, low global read latency, medium setup difficulty
Multi Region, Active-Active
- Similar to above, but both regions have active instances (read / write)
- Low global read and write latency, difficult to setup