For enthusiasts new to IP Networking terminology, VLAN and IP Subnet terms may look confusing. Many times in technical discussions things like Inter VLAN communication, interchangeably using terms like VLAN A / VLAN B or Subnet A/Subnet B are used. This further adds salt to the wound.
So, let’s have brief on terminologies of VLAN and IP Subnet and how both differ from each other.
A VLAN is a layer 2 term, usually referring to a broadcast domain. Layer 2 is where MAC addresses are used. A subnet is a layer 3 term.
Layer 3 is the IP layer where IP addresses as used. Although one can have more than one subnet or address range per VLAN, it is recommended that VLANs and Subnets are 1 to 1. In general, we will have a 1:1 mapping of subnets and VLANs i.e. One subnet per VLAN.
VLAN vs SUBNET –
| PARAMETER | VLAN | SUBNET |
|---|---|---|
| Philosophy | VLAN is a logical local area network that contains broadcasts within itself and only hosts that belong to that VLAN will see those broadcasts. | Subnet is an IP address range of IP addresses that help hosts communicate over layer 3. |
| Logical and Physical Networks | VLANs allow us to create different logical and physical networks | IP subnetting allows us to create logical networks through the same physical network. |
| Network Member control | In VLANs, the network to which a host belongs to is decided by the interface to which it is connected (layer 2) i.e. port of Switch to which host is connected. | In subnets, the network to which host belongs is decided by the ip address assigned to the host (layer 3). |
| OSI Layer | VLAN is a Layer 2 term where MAC addresses work | Subnet is a layer 3 term where IP Layer works |
| Hardware /Software based | More of Software based terminology | More of Hardware based terminology |
| Security & Control | VLANs provide more robust Control for the network | Subnetting has limited level of control in comparison to VLAN |
| Major benefit | The primary advantage of VLANs is that they break up the broadcast domain | The primary advantage of IP Subnetting is for communication across hosts in same IP subnet and same VLAN |
| Related terms | MAC Address, dot1q tag, Layer 2, Broadcast domain. | IPv4/Ipv6 address, Layer 3, InterVlan Routing |
Download the difference table here.
