Reasons for using a layer-3 Switch: expert recommendation

Several reasons for using a layer-3 Switch: recommended by experts, the most important reason is the MAC address and more stable network. The basic function of the exchange is to connect the input and output ports to achieve business flow forwarding. In the past, layer-2 packet exchanges used MAC addresses to identify the destination of data packets, that is to say, layer-2 switching refers to forwarding the business flow based on the layer-2 address.

Layer-3 switches are forwarding traffic based on layer-3 addresses. In addition to functions similar to layer-2 switching, such as switching, authentication, and packet filtering, layer-3 switches can also be used for routing, this is also the feature of using a layer-3 switch.

We know that layer-2 switching is based on MAC addressing, but for devices we want to contact, the MAC address is only a physical address, not a logical address, in practical applications, we need more addresses than simple physical addresses to meet application requirements, while layer-3 IP addresses are more suitable than MAC addresses.

TCP/IP is the communication interface of many applications. It indicates the Logical Address of the actual communication target and the address of the device we want to contact. The NICS in our network have their own unique MAC addresses, while the MAC addresses are not directly understood by applications during data transmission.

During the data transmission process, the physical address is constantly changing, but the logical address remains intact. In order to work more conveniently and quickly, we use a removable addressing IP address to obtain information about the data destination without considering the underlying information, and using an IP address provides better scalability.

A lan switch is easy to use and cost-effective, and has excellent performance. However, we cannot build a large network on a switch. A fully-built LAN on a vswitch looks like a broadcast network. Collision, congestion, and communication problems will make your network messy. A vro can be used to divide the network into multiple subnets. the functions provided by the router can effectively implement security control policies and avoid congestion.

Data packets and data packets can only be transmitted between subnets. Because the subnet address is a layer-3 address, the routing function cannot be replaced. Another function of routing is to connect networks with different protocols. If you have a network composed of an Ethernet and a ring, you cannot use it in combination with a bridge or a switch, while a router can process multiple protocols at the same time.

While having outstanding functions, the router also has its own shortcomings that cannot be avoided. A lot of routing functions are implemented by software, which inevitably leads to network bottlenecks. In terms of speed, routing cannot be compared with switching, by using a layer-3 switch, we can solve the routing speed problem.

A layer-3 Switch uses a hardware exchange mechanism to implement the IP address routing function, thus replacing the previous software routing. A layer-3 switch can provide the network speed of layer-2 switching and the IP routing function of each connection port. When a packet on the MAC layer is received by a layer-3 Switch, if the destination address belongs to a known address, the packet is directly exchanged at the layer-2 switching speed. If the address belongs to another network, the packet is routed.

Simply put, a layer-3 switch can be used for comprehensive processing on the layer-2 and layer-3. Its price and performance can reach the position of a layer-2 switch, but can partially replace a traditional router. Compared with L2 switches, L3 switches can connect to large networks.