AWS Cookbook 2.2 Creating a Network Tier with Subnets and a Route Table in a VPC

Here’s the Table of Contents (TOC) for the provided document:

Table of Contents

1. Introduction
2. Design
3. Steps
   1. Deploy a VPC
   2. Create a Route Table
   3. Create Subnets
   4. Associate Route Table with Subnets
4. Validation Checks
5. Cleanup
   1. Delete your subnets
   2. Delete your route table
   3. Delete your VPC
   4. Unset your manually created environment variables

#aws/cookbook/Networking

Introduction

When creating a VPC in a Region, it is a best practice to spread subnet across AZs in the networking tier. The number of AZs different per region, but most have at least three. A Subnet has one route table associated with it. Route Tables can be associated with one or more subnets and direct traffic to a destination. Entries within route tables are called routes and are defined as pairs of Destination and Targets. When a route table is created a default local route is added for intra-VPC traffic.

Design

Steps

• Deploy a VPC.

VPC_ID=$(aws ec2 create-vpc --cidr-block 10.10.0.0/23 \
--tag-specifications \
'ResourceType=vpc,Tags=[{Key=Name,Value=AWSCookbook202}]' \
--output text --query Vpc.VpcId)

• Create a route table to customise traffic routes for subnets.

ROUTE_TABLE_ID=$(aws ec2 create-route-table --vpc-id $VPC_ID \
--tag-specifications 'ResourceType=route-table,Tags=[{Key=Name,Value=AWSCookbookSuryendu202}]' \
--output text --query RouteTable.RouteTableId )

• Create two Subnets in each Az to define address spaces for creating resources.

SUBNET_ID_1=$(aws ec2 create-subnet \
--vpc-id $VPC_ID \
--cidr-block 10.10.0.0/24 \
--availability-zone ${AWS_REGION}a \
--tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=AWSCookbookSuryendu202a}]' \
--output text --query Subnet.SubnetId )


SUBNET_ID_2=$(aws ec2 create-subnet \
--vpc-id $VPC_ID \
--cidr-block 10.10.1.0/24 \
--availability-zone ${AWS_REGION}b \
--tag-specifications 'ResourceType=subnet,Tags=[{Key=Name,Value=AWSCookbookSuryendu202b}]' \
--output text --query Subnet.SubnetId )

• Associate the route_table created in step 2 with the Subnets.

aws ec2 associate-route-table \
--route-table $ROUTE_TABLE_ID --subnet-id $SUBNET_ID_1

aws ec2 associate-route-table \
--route-table $ROUTE_TABLE_ID --subnet-id $SUBNET_ID_2

• This generates an output similar to this respectively for each subnet.

{
    "AssociationId": "rtbassoc-0c58de60a9584de72",
    "AssociationState": {
        "State": "associated"
    }
}

{
    "AssociationId": "rtbassoc-0a7e8c81bae6bd16c",
    "AssociationState": {
        "State": "associated"
    }
}

Validation Checks

We can describe each resource to validate deployments.

1. Subnet 1
2. Subnet 2
3. Route Table

Cleanup

Delete your subnets:

aws ec2 delete-subnet --subnet-id $SUBNET_ID_1

aws ec2 delete-subnet --subnet-id $SUBNET_ID_2

Delete your route table:

aws ec2 delete-route-table --route-table-id $ROUTE_TABLE_ID

Delete your VPC:

aws ec2 delete-vpc --vpc-id $VPC_ID

Unset your manually created environment variables

unset VPC_ID
unset ROUTE_TABLE_ID
unset SUBNET_ID_1
unset SUBNET_ID_2