Matthew Howard is a computer hardware engineer. After completing his graduation, he joined a renowned networking tools manufacturing company as an IT specialist and hardware...Read more
Be it your home, school or business, wherever there’s a wi-fi connection, you will surely find a router. Without these handy little devices, we’d never be able to access the internet on which we all rely. But not all LANs are built around routers; some networks, particularly large and complex enterprise networks, are built around a device known as a layer 3 switch.
In simple terms, a layer 3 switch is a network switch (i.e. it connects devices on a computer network) which also performs some of the functions of a router. A layer 3 switch and a router incorporate many of the same features. However, there is one primary advantage of the former over the latter: since packets on a layer 3 switch don’t need to make additional steps through a router, it experiences significantly less latency.
- A layer 3 switch and a router perform many of the same functions, but the former experiences less network latency.
- Layer 3 switches are designed for large corporate LANs that handle high volumes of traffic; they combine the functionality of a standard multilayer network switch with a router.
- Layer 3 switches are more cost effective than routers for high speed inter-VLAN networking, and offer greater flexibility.
- Routers are more suitable for smaller networks; they offer WAN functionality, which layer 3 switches lack.
- What Is The Purpose Of A Layer 3 Switch?
- Comparison Of The Features Of Layer 3 Switch Vs Router:
- About Layer 3 Switches
- About Routers
What Is The Purpose Of A Layer 3 Switch?
A layer 3 switch combines the capacities of a multilayer networking switch with that of a router. It rapidly connects devices on the same subnet or virtual LAN, and has organic routing intelligence capabilities so it can serve as a router. They were designed to replace layer 2 switches on large corporate networks, since the layer 2 switches could not handle large volumes of traffic. Routers could be introduced to handle this problem, but they would be slower than conventional switches. Hence, the layer 3 switch was designed to provide the best of worlds.
Comparison Of The Features Of Layer 3 Switch Vs Router:
|ATTRIBUTE||LAYER 3 SWITCH||ROUTER|
|Use Case||LAN for Corporate, Date Center, or Campus environment.||WAN networks, private houses.|
|Core Functionality||Separates ports into virtual LANs and performs the routing between them.||Connects multiple packet-switched networks and subnetworks.|
|VPN and MPLS Services||Does not support VPN or MPLS.||Provides VPN and MLS services.|
|Size of Routing Tables||Smaller routing tables than routers.||Routing tables are large, so as to support multiple route entries.|
|Forwarding Decision-making||Specialized ASICs perform forwarding decisions.||Router’s organic software performs forwarding decisions.|
|Interface Support||Support copper and fiber ethernet ports. SONET, T-1/T-3 etc. not supported.||Supports both ethernet ports and interfaces like SONET, T1-T3 etc.|
|Switching Capacity||High switching capacity.||Low switching capacity.|
|Port Density||High port density.||Low port density.|
|Throughput||Higher throughput.||Lower throughput.|
|Examples||Cisco 3560, 3650 and 6500.||Cisco 3900, 4000 Series ISR|
About Layer 3 Switches
Layer 3 switches make it easier to use LANs and VLANs. They are crucial for enterprise networks which have multiple subnets and VLANs. It makes VLANs easier to configure by eliminating the need to install a router between each VLAN; the switch itself handles routing responsibilities.
Possible Use Cases For Layer 3 Switches
Some of the use cases for Layer 3 switches are:
- Enterprise and corporate LANs.
- Date center LANs.
- Campus LANs for schools, colleges etc.
Layer 3 Switches: Benefits and Drawbacks
Some of the advantages of using a layer 3 switch are:
- Network latency is reduced considerably, since data packets don’t have to make additional steps through the router.
- They support routing between virtual LANS.
- Routing tables are separate, and hence traffic is segregated more smoothly.
- Simplified security management.
- Smooth flow accounting and high-speed scalability.
Some of the drawbacks of using a layer 3 switch are:
- They are a significantly pricier option than conventional multilayer switches. You will have to devote a lot of time and effort towards configuring and administering these switches.
- They completely lack WAN functionality, meaning you’ll still need routers to route the internal and external traffic of your organization.
- A given VLAN will always be connected with one switch only. It can’t be used in conjunction with any other switch.
A router directs and guides network data, using packets of different types of data. The data packets have many sections, or layers, which contain information such as the identity of the sender, type and size of the data, and IP address of the destination. The router decides the best route for each packet on the basis of these layers.
Use Cases for Routers:
Some of the possible use cases for routers are:
- WANs for enterprises, data centers and campuses.
- Internet connections for private houses and other personal use.
Routers: Pros and Cons
The benefits of using a router are:
- Provides complicated flow control, routing, and traffic isolation.
- Reduces network traffic.
- Can connect distinct network architectures.
Some of the drawbacks of using a router are:
- They are comparatively slow.
- They require a large number of initial effort and infrastructure implementations.
- They are more expensive than many other network services.
Can Layer 3 Switches Replace Routers?
Layer 3 switches certainly offer better functionality than routers in many aspects, with the speed of transmission being the most important. However, they are also lacking in several other aspects; notably, they offer no WAN functionality whatsoever, and do not support interfaces like SONET, T1/T-3 etc. Hence, even for large enterprises, it is unlikely that layer 3 switches will completely replace routers since at least some WAN capacity will always be required.
Are Layer 3 Switches Better Than Routers?
Whether a layer 3 switch is better than a router depends completely on the context of your particular needs. If you’re an enterprise or have otherwise large LANs, incorporating layer 3 switches into your system will certainly offer better performance than using routers only. On the other hand, if you want an internet connection for personal or residential use, a layer 3 switch will be completely superfluous and you’ll be much better off with a router.
In conclusion, a layer 3 switch is a device that combines the functionalities of a network switch and a router. It offers better network speed than routers, at the cost of WAN capacities. Whether you should use only routers, or a combination of layer 3 switches and routers, depends entirely on the context of your needs.