Basic Design and Implementation of the Cisco EI CCIE Enterprise Network

How to understand the difference between Layer 3 Switches and Routers
I’ve been working with network technology for years, but what’s the difference between layer 3 switches and routers? There will always be many people who don’t know. What is the difference? It is important to fully understand the difference.
Layer-2 switch’s simplest principle is to forward data according the MAC address table. It serves four functions: forwarding, broadcasting, learning, and updating.
The exchange opportunity stores the mapping between the source MAC addresses of the data frames and the corresponding ports in the MAC Address table when a data frame arrives. This information is used to forward data. Today’s data forwarding uses the target MAC address. Query the MAC address table. Unicast forwards data frames if the MAC address table contains a corresponding mapping relation. Flood is used if there is no corresponding map relationship. Importantly, if an entry isn’t used in the MAC address list for more than 300 seconds the corresponding mapping relation will be deleted. This is the update operation of a switch.
The routing table determines how data is transmitted by the router. The router will discard any data packets that do not match the entry in the routing table. Layer 3 switch is a switch that has some router functions and works in the network layer. The main purpose of the Layer 3 switch is to speed up data exchange within large LANs. This function is also served by the routing function. It can route once and forwarded many times.
Layer 3 routers and switches also have routing functions. However, this is just a function. Many network devices have the functions of many traditional devices. The router, for example, has not only the routing function but also the functions of switch port, hardware firewall, and switch port. It is not a firewall or switch. Its primary function is routing. These are its new capabilities. We can afford to pay less for better functions. The layer 3 switch is still a switch. It has basic routing functions. It is still responsible to data exchange and there are many interfaces. The router has only the main function, routing and forwarding, but not the switch function.
There are many differences between routers, layer 3 switches and routers in data forwarding operation. Layer-3 switches transmit data through hardware and software, while routers typically forward data based upon hardware and software. The layer 3 switch will create a mapping table containing MAC address and IP address after routing a data stream. The same data stream will be routed again from layer 2, but it will go directly to layer 2. This is to reduce network delay and increase packet forwarding efficiency. The router forwarding uses the longest matching method, which can be difficult to implement. It is often realized using software, so the forwarding efficiency of this method is low.
The overall performance of layer-3 switches is superior to routers in terms of overall performance. It is well-suited for LANs with frequent data exchange. The router’s routing function is powerful, but its packet forwarding efficiency, while lower than that of a layer 3 switch, is more suitable to interconnect different types of networks with less frequent data exchange.
How to understand the difference between Layer 3 Switching & Router in the Basic Design & Deployment for the New Cisco EI CCIE Enterprise Network.
Because it is primarily a simple LAN connection, the routing function of layer 3 switches and routers are very simple. The routing function of layer three switches is typically simple and the routing path is much simpler than that of routers. Its primary function in LAN is data exchange to meet the application characteristics for frequent data exchange and large traffic. The Router is a different type. It was originally designed to connect various types of network connections. It can be used to connect LANs. However, its routing function is more focused on interconnecting different types of networks such as different network protocols and network types. It is capable of connecting complex routing paths networks, and is therefore very powerful. It has the ability to choose the best route, load share, link backup, and exchange routing information with other networks.
Layer 3 switches and routers have many essential differences. The router can still be completely replaced by the layer 3 switch. The router’s rich interfaces, traffic service level control and strong routing capabilities are still weak ties.