EC2 – Associate

Private vs Public IP (IPv4)

• Networking has two sorts of IPs. IPv4 and IPv6:

• IPv4: 1.160.10.240

• IPv6: 3ffe:1900:4545:3:200:f8ff:fe21:67cf

• In this course, we will only be using IPv4.

• IPv4 is still the most common format used online.

• IPv6 is newer and solves problems for the Internet of Things (IoT).

• IPv4 allows for 3.7 billion different addresses in the public space

• IPv4: [0-255].[0-255].[0-255].[0-255].

Private vs Public IP (IPv4) Fundamental Differences

• Public IP:

• Public IP means the machine can be identified on the internet (WWW)

• Must be unique across the whole web (not two machines can have the same public IP).

• Can be geo-located easily

• Private IP:

• Private IP means the machine can only be identified on a private network only

• The IP must be unique across the private network

• BUT two different private networks (two companies) can have the same IPs.

• Machines connect to WWW using a NAT + internet gateway (a proxy)

• Only a specified range of IPs can be used as private IP

Elastic IPs

• When you stop and then start an EC2 instance, it can change its public IP.

• If you need to have a fixed public IP for your instance, you need an Elastic IP

• An Elastic IP is a public IPv4 IP you own as long as you don’t delete it

• You can attach it to one instance at a time

• With an Elastic IP address, you can mask the failure of an instance or software by rapidly remapping the address to another instance in your account.

• You can only have 5 Elastic IP in your account (you can ask AWS to increase that).

• Overall, try to avoid using Elastic IP:

• They often reflect poor architectural decisions

• Instead, use a random public IP and register a DNS name to it

• Or, as we’ll see later, use a Load Balancer and don’t use a public IP

Private vs Public IP (IPv4) In AWS EC2 – Hands On

• By default, your EC2 machine comes with:

• A private IP for the internal AWS Network

• A public IP, for the WWW.

• When we are doing SSH into our EC2 machines:

• We can’t use a private IP, because we are not in the same network

• We can only use the public IP.

• If your machine is stopped and then started, the public IP can change

Placement Groups

• Sometimes you want control over the EC2 Instance placement strategy

• That strategy can be defined using placement groups

• When you create a placement group, you specify one of the following strategies for the group:

• Cluster—clusters instances into a low-latency group in a single Availability Zone

• Spread—spreads instances across underlying hardware (max 7 instances per group per AZ)

• Partition—spreads instances across many different partitions (which rely on different sets of racks) within an AZ. Scales to 100s of EC2 instances per group (Hadoop, Cassandra, Kafka)

Cluster

• Pros: Great network (10 Gbps bandwidth between instances with Enhanced Networking enabled - recommended)

• Cons: If the rack fails, all instances fails at the same time

• Use case:

• Big Data job that needs to complete fast

• Application that needs extremely low latency and high network throughput

Spread

• Pros:

• Can span across Availability Zones (AZ)

• Reduced risk is simultaneous failure

• EC2 Instances are on different physical hardware

• Cons:

• Limited to 7 instances per AZ per placement group

• Use case:

• Application that needs to maximize high availability

• Critical Applications where each instance must be isolated from failure from each other

Partition

• Up to 7 partitions per AZ

• Can span across multiple AZs in the same region

• Up to 100s of EC2 instances

• The instances in a partition do not share racks with the instances in the other partitions

• A partition failure can affect many EC2 but won’t affect other partitions

• EC2 instances get access to the partition information as metadata

• Use cases: HDFS, HBase, Cassandra, Kafka

Elastic Network Interfaces (ENI)

• Logical component in a VPC that represents a virtual network card

• The ENI can have the following attributes:

•Primary private IPv4, one or more secondary IPv4

• One Elastic IP (IPv4) per private IPv4

• One Public IPv4

• One or more security groups

• A MAC address

• You can create ENI independently and attach them on the fly (move them) on EC2 instances for failover

• Bound to a specific availability zone (AZ)

EC2 Hibernate

• We know we can stop, terminate instances

• Stop – the data on disk (EBS) is kept intact in the next start

• Terminate – any EBS volumes (root) also set-up to be destroyed is lost

• On start, the following happens:

• First start: the OS boots & the EC2 User Data script is run

• Following starts: the OS boots up

• Then your application starts, caches get warmed up, and that can take time!

• Introducing EC2 Hibernate:

• The in-memory (RAM) state is preserved

• The instance boot is much faster! (the OS is not stopped / restarted)

• Under the hood: the RAM state is written to a file in the root EBS volume

• The root EBS volume must be encrypted

• Use cases:

• Long-running processing

• Saving the RAM state

• Services that take time to initialize

EC2 Hibernate – Good to know

• Supported Instance Families – C3, C4, C5, I3, M3, M4, R3, R4, T2, T3, …

• Instance RAM Size – must be less than 150 GB.

• Instance Size – not supported for bare metal instances.

• AMI – Amazon Linux 2, Linux AMI, Ubuntu, RHEL, CentOS & Windows…

• Root Volume – must be EBS, encrypted, not instance store, and large

• Available for On-Demand, Reserved and Spot Instances

• An instance can NOT be hibernated more than 60 days

EC2 Nitro

• Underlying Platform for the next generation of EC2 instances

• New virtualization technology

• Allows for better performance:

• Better networking options (enhanced networking, HPC, IPv6)

• Higher Speed EBS (Nitro is necessary for 64,000 EBS IOPS – max 32,000 on non-Nitro)

• Better underlying security

• Instance types example:

• Virtualized:A1, C5, C5a, C5ad, C5d, C5n, C6g, C6gd, C6gn, D3, D3en, G4, I3en, Inf1, M5, M5a, M5ad, M5d, M5dn, M5n, ….

• Bare metal: a1.metal, c5.metal, c5d.metal, c5n.metal, c6g.metal, c6gd.metal…

EC2 – Understanding vCPU

• Multiple threads can run on one CPU (multithreading)

• Each thread is represented as a virtual CPU (vCPU)

• Example: m5.2xlarge

• 4 CPU

• 2 threads per CPU

• => 8 vCPU in total

EC2 – Capacity Reservations

• Capacity Reservations ensure you have EC2 Capacity when needed

• Manual or planned end -date for the reservation

• No need for 1 or 3 -year commitment

• Capacity access is immediate, you get billed as soon as it starts

• Specify:

• The Availability Zone in which to reserve the capacity (only one)

• The number of instances for which to reserve capacity

• The instance attributes, including the instance type, tenancy, and platform/OS

• Combine with Reserved Instances and Savings Plans to do cost saving