In the OSI model, we learnt that Switches belong to Layer 2 while Routers belong to Layer 3.Switches are understood to be forward traffic based on MAC address while Routers perform the forwarding based on IP address. However, Layer 3 Switch is another term which tends to make networking beginners puzzled. 1st Question that comes into mind – What is Layer 3 Switch all about and how is it different from Router?
A Layer 3 switch is both a Switch and a Router. We can call it a router with multiple Ethernet ports and has a switching functionality. It switches packets by checking both their IP addresses and their MAC addresses. Layer 3 switches thus separates ports into virtual LANs (VLANs) and perform the routing between them in addition to supporting routing protocols such as RIP, OSPF and EIGRP. Another name for Layer 3 Switch is “Multilayer Switch”.
From 1st look, it may seem that Layer 3 Switch and Router perform the same functionality, however a deep inspection of both the terms will open some key distinction facts.
Below is illustration of how both differ from each other –
So let’s summarise, some key difference between Layer 3 Switch and Router –
- Cost— Layer 3 switches are much more cost effective than routers for delivering high-speed inter-VLAN routing. High performance routers are typically much more expensive than Layer 3 switches.
- Port density— Layer 3 switches, have much higher port count while Routers have a lower port density than Layer 3 Switches.
- Flexibility— Layer 3 switches allow you to mix and match Layer 2 and Layer 3 switching, meaning you can configure a Layer 3 switch to operate as a normal Layer 2 switch, or enable Layer 3 switching as required.
- WAN technologies support – Layer 3 Switch is limited to usage over LAN environment where Inter VLAN routing can be performed, however when it comes to working on WAN and edge technologies Layer 3 Switch lags behind. Router is the front runner in such scenario where WAN technologies such as Frame Relay or ATM need to be fostered.
- Hardware/Software decision making – The key difference between Layer 3 switches and routers lies in the hardware technology used to making forwarding decision.in case of Layer 3 Switch specialized ASICs are used for forwarding decision while in case of Routers generally it’s the software logic which it uses.