Amazon Web Services Networking

We'll start with high-level concepts:

• What AWS services are relevant to a networking engineer?
• What are regions and availability zones?
• How do you implement high availability in AWS environment?

Virtual Private Cloud (VPC) service is the foundation of AWS networking. This section describes VPC concepts, subnets within VPCs, and VPC/subnet addressing.

Subnets are useless without servers connected to them. In this section we'll focus on AWS implementation of VM network interfaces, network interface addressing, and supporting services like DNS and DHCP.

The section also covers advanced concepts like public and private IP addresses, elastic IP addresses, and elastic network interfaces.

AWS offeres several layers of network security:

• Stateful security groups applied to VM interfaces;
• Stateless network ACLs applied to subnets;
• Validation of source and destination IP addresses.

All these mechanisms (and the logging functionality available with flow logs) are described in this section.

VPC Route Tables are almost like VRFs with a few significant differences:

• Route tables are applied to subnets;
• All route tables share the entry for local VPC CIDR block.

This section describes the route tables and details of packet forwarding within VPC.

VPC Internet connectivity is usually provided through an Internet gateway. IPv6 hosts that don't provide services to outside clients can use egress-only gateway; similar IPv4 hosts can access Internet through NAT gateway or NAT instance.

This section describes all three mechanisms, and the adjustments to route tables that have to be made to support them.

This section describes other external connectivity options available in AWS VPC - IPsec VPN connections, router-to-router VLAN connections (Direct Connect), inter-VPC peering, and Transit Gateways.

AWS provides a variety of load balancing mechanisms, from local L4 load balancing (Network Load Balancing) and HTTP load balancing to global load balancing with DNS and anycast IP addresses.