In the networking world, term like layer 3 switch and router gets thrown around often – both are seeing broad deployment in network data transmission. Generally speaking, a layer 3 switch connects hosts to form local area networks (LANs) while routers connect multiple LANs into wide area networks (WANs). We may get confused regarding layer 3 switch vs router: they bear much similarities as they both support the same routing protocols, inspect incoming packets and make dynamic routing decisions based on the source and destination addresses inside. But they also differ in performance, flexibility, cost and etc. So we’re going to explain them in an explicit way, and help you to make the right decision.
Layer 3 Switch: Mix And Match Layer 2/3 Switching
The OSI (Open Systems Interconnection) model is a standardized reference model that explains how applications communicate over a network. It consists of seven layers, from the physical layer to the application layer. Traditional switches operate at Layer 2 (Data-Link Layer), forwarding packets based on MAC addresses, while routers operate at Layer 3 (Network Layer), directing packets based on IP addresses.
A layer 3 switch is a device that forwards traffic (frames) based on layer 3 information (mainly through mac-address). Layer 3 switch supports all switching features, while also has some basic routing functions to route between the VLANs. Layer 3 switch is conceived as a technology to improve network routing performance on large LANs. Of a layer 3 switch, layer forwarding is performed by specialized ASICs – it is faster than routers, but they usually lack some of the advanced functionalities of routers. Unlike routers, a layer 3 switch is less likely to experience network latency since packets don’t have to make additional steps through a router. Given that layer 3 switches perform functions associated with both layer 2 and layer 3, it is also refer to as “multilayer switch”, and some 10GbE switch and Gigabit PoE switch are of this type.
Advantages of Layer 3 Switches:
Enhanced Routing: Layer 3 switches make routing decisions based on IP addresses, resulting in faster packet processing and reduced latency.
Network Segmentation: With VLAN support, Layer 3 switches improve security, reduce network traffic, and enhance network management.
Scalability and Flexibility: Layer 3 switches facilitate network expansion by enabling communication across multiple LANs.
Optimized Traffic Management: Layer 3 switches prioritize and manage traffic based on service parameters, ensuring efficient bandwidth usage.
Seamless Integration: Layer 3 switches can replace routers, improving network communication and reducing costs.
Centralized Management: Layer 3 switches offer centralized control of routing and switching functions, simplifying network configuration and maintenance.
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Router: For Different Networks & Protocols
The router is a ubiquitous hardware applied in home and small business networks. It allows communication between devices that attached to it and the internet. A router can forward traffic (packets) based on layer 3 information using IP address. This allows the network to go across different Protocols. Routers also serve as the first line security that protects the network from any attack and intrusion. Working to route the packets to their destination, a router analyzes the layer 3 destination address of every packet, and decides the best next hop for it. This process takes time, and hence every packet encounters some delay because of this.
Types of Routers:
Core router: Provides high-bandwidth connectivity for large-scale networks used by service providers and cloud providers.
Distribution router: Routes data from edge routers to end users, often supporting Wi-Fi and Ethernet connections.
Edge router: Connects networks to external networks like the Internet, optimized for bandwidth distribution.
Virtual router: Software-based router deployed in the cloud, offering flexibility and scalability for complex network needs.
Wireless router: Combines edge and distribution router functions, commonly used in home networks for wireless connectivity.
The basic features of layer 3 switch vs router are listed below:
Features | Layer 3 Switch | Router |
|---|---|---|
Layer 3 basic routing | Yes | Yes |
Traffic management | Yes | Yes |
WIC card support | No | Yes |
Advance routing features | No | Yes |
Forwarding Architecture | Hardware-ASIC | Software-IOS |
RMON support | Yes | No |
Policy performance | High | Low |
WAN support | No | Yes |
WAN interfaces | No | Yes |
QoS features | No | Yes |
NAT | No | Yes |
LAN capabilities | Yes | No |
How Do Layer 3 Switches and Routers Cooperate in a Network?
Layer 3 switches and routers collaborate to ensure a smooth network operation. Layer 3 switches handle intranetwork traffic routing, while routers manage the connections between different networks. When a packet reaches a Layer 3 switch, the switch examines its destination IP address. If the destination lies within the same network segment, the switch forwards it directly. If the destination IP corresponds to a different network, the Layer 3 switch passes the packet to a router, which then directs it to its appropriate network destination. This cooperation enhances network performance, reliability, and optimizes resource use by assigning specific tasks based on each device's capabilities.
Layer 3 Switch VS Router: Similarities and Differences
Similarities:
A layer 3 switch is both a switch and a router: it can be regarded as a router with multiple Ethernet ports and with switching function. Layer 3 switch enables packets switching by inspecting both their IP addresses and their MAC addresses. Layer 3 switches are thus able to segregate ports into separate VLANs and perform the routing between them. Like traditional routers, a layer 3 switch can also be configured to support routing protocols such as RIP, OSPF, and EIGRP.
Differences:
Hardware - The key difference between layer 3 switch and router lies in the hardware. The hardware inside a layer 3 switch blends that of traditional switches and routers, improving some of a router’s software logic with integrated circuit hardware to offer better performance for LANs. Additionally, designed specifically for use on intranets, a layer 3 switch usually has no WAN ports and features a traditional router usually gets. So layer 3 switch is most used to support routing between VLANs.
Interfaces - Another difference regarding a layer 3 switch vs router is that a Layer 3 switch is limited in interfaces it supported (usually just Ethernet for RJ45 and single mode/multimode fiber). While a router has more options like SDH, SONET, E1/T1 etc. Moreover, routers were devices that connected the LAN to the WAN and switches were just LAN devices.
The Working Principle - Layer 3 switch looks at the MAC address of the destination host and sends the frame only to that recipient. A router refers to the target IP address instead of its MAC address, thus it generally provides more functionality than mere packet routing, such as IP address assignment (DHCP) and firewall filtering.
Layer 3 switches can optimize LAN performance. Routers connect LANs to WANs, support various interfaces like SDH and SONET, and provide additional features like DHCP and firewall filtering based on IP addresses. Except for the three major differences concerning layer 3 switches and routers, some other aspects are summarized in the following chart to help distinguish layer 3 switches from routers.
Attribute | Layer 3 Switch | Router |
|---|---|---|
Scope | LAN for office, data center and campus environment | WAN for office, data center and campus environment |
Key Functionality | Routes across different subnets or VLANs on a campus LAN | Routes across different networks across WAN are communicated and routed by a router |
Edge Technologies Support | Not supported | NAT, firewalling, tunneling, IPSec |
Size of Routing Table | Smaller routing table compared to router | Considerably bigger to support multiple route entries |
Forwarding Decision | Forwarding is performed by specialized ASICs | Performed by software |
Interface Support | Ethernet ports (copper/fiber) | Ethernet ports (copper/fiber), interfaces like SONT, OC-N, T1/T3 etc. |
Throughout | High throughput | Lower than Layer 3 switches |
Switching Capacity | High switching capacity | Lower than Layer 3 switches |
Cost | Low cost | High cost |
Port Density | High | Low |
Layer 3 Switch Vs Router: How to Choose?
One of the general talk relating layer 3 switch vs router is that if there is a router why we required layer 3 switch. In fact, they each can be deployed to various situations and scenarios. Based on the similarities and differences we’ve explained, your choices actually depends on your network design and what you are trying to accomplish.
For Layer 3 Switch:
Lack of WAN ability, the application of layer 3 switches often falls into intranet environments with a sufficiently large scale of device subnets and traffic. It can justify the following scenarios:
Departments need their own broadcast domains for performance or security.
Connect your Hub rooms and make a layer 3 decision, providing more Ethernet interfaces for direct server form connectivity than router.
Connect your inter-offices via layer 2 circuits by the ISP, you can directly terminate the link on the layer 3 switch and configure routing on it at the same time.
When you need more through-put and direct access and inter-VLAN communication, a layer 3 switch is the best bet.
Network with a lot of broadcasts that needs better performance VLANS.
For Router:
As WAN links become more Ethernet based, there is an increasing trend to substitute layer 3 switches for routers. However, routers still possess some special features that a layer 3 switch cannot support. It is unreplaceable in these situations.
If you’re about to connect an ISP directly to provide internet, router is made for this.
If you need to build tunnels between your offices, for example, to connect two offices over public internet in a more secured way, a router can better suit the need.
If you are a CE participating in MPLS configuration, then you need a router.
Conclusion
When regarding to choose between a layer 3 switch and a router, you need to understand the business requirement before make your decision: in general, it is proper to get a router when most of the time your device does the routing, otherwise, a layer 3 switch may fit better when you need more ports, better network performance and VLAN segmentation. FS.com provides a full set of network switch solutions and products, including SFP switches, copper switches and higher-end 40/100G switches. For more details, kindly contact us via FS.com.
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