How to connect a layer-3 router switch

At present, China's routing industry is developing at a high speed, and it also promotes the constant update and upgrade of routing technology. Here we mainly explain the connection methods of layer-3 routing switches. As for the stack of routing switches, not all vswitches are allowed, but stack modules are required. The stack of A vswitch is connected through a dedicated stack cable instead of a switching port.

Note that the stack of the route switch is usually placed in the same location, and the connection cable is short. Therefore, the stack of the route switch is mainly used to expand the switch port, it is not used to expand the distance. At the same time, the switch stack can also increase the available bandwidth of each actually used switch port because it aggregates the Board bandwidth of the route switch that is stacked together, in this way, the total backplane of the routing switch stack is the sum of the bandwidth of several stack switches.

After the increase in the bandwidth of the backboard, if each port of the route switch is used, this advantage is not very obvious (it is also effective because it is impossible to communicate with each port at the same time ), however, if a vswitch port is idle, the effect will be more obvious because it can take full advantage of all the bandwidth of the route switch. The stack connection ports of a vswitch are usually arranged in the D-Jack format. A routing switch has two such ports marked with "UP" and "DOWN", as shown in ), it indicates that it is used to connect up and up the stack, and cannot be connected to an error.

Layer-3 route switch route connection

As we mentioned earlier, layer-3 routing switches also have certain "routing" functions to achieve connections between different subnets. However, it should be noted that its routing function is much weaker than that of a router. The routing function of a layer-3 router switch can only be used for interconnection between networks of the same type. Generally, it is only the interconnection between LAN subnets and does not connect the LAN to the WAN or the Internet, because layer-3 switches support very limited routing protocols, after all, this is not its main function.

We know that on the LAN, a layer-2 switch identifies the packet sender through the source MAC address and forwards the packet according to the destination MAC address. For a data packet whose destination address is not on the local area network, a layer-2 switch cannot directly send it to the destination. It must be forwarded by a routing device (such as a traditional router, connect the vswitch to the routing device. If the default gateway of the route switch is set as the IP address of the router device, the route switch sends the packet to be forwarded by the route device.

The routing device checks the destination address of the data packet and its route table. If the route table finds the forwarding path, the routing device forwards the data packet to other network segments. Otherwise, the data packet is discarded. A dedicated router is expensive, complex, slow, and easy to become a network bottleneck because it needs to analyze all the broadcast packets and forward some of them, and exchange route information with other routers, in addition, these processes are all processed by the CPU (not dedicated ASIC ). A layer-3 Switch identifies a packet forwarding through a MAC address like a layer-2 router, and can also forward packets between two network segments as a traditional router. Traditional routers use software to maintain route tables, while layer-3 switches use dedicated ASIC chips to process route forwarding. Compared with traditional routers, the routing speed of layer-3 route switches is generally 10 times faster or dozens of times faster.