In AWS networking, traditional VLANs (Virtual Local Area Networks), which are commonly used in on-premises
networking to segment traffic within a data center or across a LAN, do not directly exist. However, similar
concepts to VLAN segmentation are implemented using AWS networking services, specifically Virtual Private Clouds
(VPCs) and subnets.
While AWS does not natively use VLANs, it offers the functionality and control you'd expect from VLANs in a
cloud-native way.
Below is an overview of how AWS VPCs and subnets provide equivalent functionality to VLANs and how you can use
them in an AWS environment.
1. VPCs as Logical Isolation (Similar to VLANs)
An AWS VPC (Virtual Private Cloud) is the fundamental building block of networking in AWS. It is used to logically isolate your network within AWS, similar to how VLANs provide logical isolation in traditional networks. VPCs provide network segmentation: In AWS, you can create multiple VPCs within a single region or across regions to isolate workloads, services, and resources. Traffic control and segmentation: Like VLANs, VPCs allow you to control the flow of traffic between resources. You can configure routing tables, network access control lists (NACLs), and security groups to control inbound and outbound traffic. Multiple VPCs for segmentation: Just like you would use multiple VLANs to segregate network traffic, you can use multiple VPCs to segment different environments or teams in AWS (e.g., production, staging, development).
2. Subnets as Network Segmentation within a VPC
Within a VPC, subnets are used to segment the network across different Availability Zones (AZs). This is
conceptually similar to VLANs where subnets help you divide the network space into isolated sections for
security, performance, or compliance.
Subnets within a VPC are akin to different VLANs within the same physical network. Each subnet in AWS can
represent a different network segment where you deploy your resources like EC2 instances, RDS databases, and
Lambda functions.
Public and private subnets: You can create public and private subnets within a VPC to control whether resources
can be accessed from the internet (public) or remain isolated from it (private).
Example of using subnets like VLANs:
Subnet 1: Public subnet for internet-facing web servers.
Subnet 2: Private subnet for application servers that only the web servers can reach.
Subnet 3: Private subnet for databases that only application servers can reach.
This structure provides network isolation similar to how VLANs might segregate traffic on different logical
networks in an on-premises environment.
3. Security Groups and NACLs for Network Control
In traditional VLANs, network segmentation is enforced by firewalls or access control lists. In AWS, you use Security Groups and Network ACLs (NACLs) to manage network traffic between resources and subnets. Security Groups: Act as virtual firewalls attached to AWS resources (like EC2 instances) that control inbound and outbound traffic at the instance level. Security groups are stateful, meaning that if a connection is allowed inbound, the outbound connection is automatically allowed. NACLs (Network ACLs): Act at the subnet level and control inbound and outbound traffic. NACLs are stateless, meaning you must configure both inbound and outbound rules separately. They are similar to VLAN access control rules on switches or routers. These tools allow you to implement security policies for traffic flow between subnets and other parts of your AWS network, much like VLANs would enforce access control within an on-premises network.
4. AWS Transit Gateway and VPC Peering
In on-premises networks, VLANs can be interconnected using routers or Layer 3 switches to enable traffic between
them. In AWS, you can connect VPCs in similar ways:
VPC Peering: Allows you to connect two VPCs directly so that they can route traffic to each other using private
IPs. This is similar to inter-VLAN routing in traditional networking.
AWS Transit Gateway: This service acts as a central hub to interconnect multiple VPCs and on-premises networks.
Instead of creating many VPC peerings, you can attach VPCs to a Transit Gateway to control the routing between
them, similar to how you would use a router to control traffic between VLANs.
5. AWS Direct Connect and VLANs
In AWS, AWS Direct Connect supports VLAN tagging for creating dedicated connections between your on-premises
data center and your AWS environment. With Direct Connect, you can use 802.1Q VLAN tagging to establish multiple
logical connections (virtual interfaces or VIFs) over a single physical connection.
Private VIF: Can be used to extend your on-premises data center VLAN into an AWS VPC.
Public VIF: Used for accessing public AWS services like S3 over the Direct Connect connection.
Each VIF can be associated with a different VLAN ID, allowing you to logically segment traffic over your
dedicated connection.
6. AWS Outposts and VLAN Support
If you're using AWS Outposts, which extends AWS infrastructure to on-premises data centers, VLANs are supported for network integration. AWS Outposts can be connected to on-premises environments using VLANs to integrate seamlessly with existing network infrastructure.
Summary:
How VLAN Concepts Map to AWS Networking
VLAN Feature/Concept AWS Equivalent
VLANs (Logical Segmentation) VPCs provide logical isolation of network traffic.
Subnetting within VLANs Subnets segment networks within a VPC (e.g., public, private subnets).
Inter-VLAN Routing VPC Peering or AWS Transit Gateway connects multiple VPCs.
Firewall Rules Security Groups and NACLs control network traffic between resources.
VLAN Tagging Direct Connect and Outposts support VLAN tagging for network integration.
Conclusion:
While AWS does not natively use VLANs like in traditional networks, the same network isolation and segmentation
capabilities are achieved through VPCs, subnets, security groups, and network ACLs. For connecting to
on-premises networks, AWS services like Direct Connect support VLANs to ensure seamless network integration.