Type Of Switch (Part 2)

The so-called "routing" refers to the behavior and actions of transferring data from one place to another, and the router is the machine that performs this kind of behavior. Its English name is Router, which is a kind of connection to multiple networks or A network device on a network segment that "translates" data between different networks or segments so that they can "read" each other's data to form a larger network. The router mainly has the following functions: first, network interconnection; second, data processing; third, network management.

The Layer 2 switch works at the second layer (the data link layer). For it, the data on the network is a collection of MAC addresses. It can distinguish the source MAC address and the destination MAC address in the frame, so it can be arbitrarily The two ports establish a connection, but the switch does not know the IP address, it only knows the MAC address.

The Layer 3 switch and router work at the third layer (the network layer). It can understand the IP address in the data. If it receives a packet, it checks the IP address. If the destination address is the local network, it will ignore it. If it is other networks, it forwards the packet out of the local network.

The word TRUNK also has different interpretations on different occasions:

In terms of the hierarchical structure of the network and the reasonable allocation of broadband, TRUNK is interpreted as “port aggregation”, which is an important way for bandwidth expansion and link backup. TRUNK bundles multiple physical ports together as a logical port, which can be used to stack multiple sets of ports. The TRU NK technology can implement the function of multiple links in the trunk of the TRUNK. That is, when one link fails, it does not affect the work of other links. At the same time, traffic balancing can be achieved between multiple links, just like we are familiar with. Printer pool is the same as MODEM pool.

2. In the voice-grade line of the telecommunication network, Trunk refers to the “backbone network and telephone trunk line”, that is, the connection circuit or channel between two exchanges or switches, which can be transferred between the two ends and provided Necessary signaling and terminal equipment.

3, But in the most common routing and switching field, VLAN port aggregation is also called TRUNK, but most of them are called TRUNKING, such as CISCO. The so-called TRUNKING is used to connect between different switches to ensure that members of the same VLAN established across multiple switches can communicate with each other. The port used for interconnecting switches is called the TRUNK port. Unlike the cascading of general switches, TRUNKING is based on the second layer of OSI. Suppose there is no TRUNKING technology. If you divide multiple VLANs on two switches (the VLAN is also based on Layer 2), then the respective members of VLAN 10 and VLAN 20 on the two switches need to be in the A switch if they want to communicate. One of the ports set to VLAN 10 is connected to a port set to VLAN 10 on Switch B. The same is true for VLAN 20. Then, if 10 VLANs are allocated on the switch, 10 lines need to be cascaded separately, and the port efficiency is too low. When the switch supports TRUNKING, the problem is simple. Only one cascaded line between the two switches is required, and the corresponding port is set as a trunk. This line can carry information about all VLANs on the switch. In this case, even if there are hundreds of VLANs on the switch, only one port is used.

If the vlans of the same id on different switches need to communicate with each other, they can be implemented through the shared trunk port. If they are vlans of different ids on the same network, different vlans of different ids need to communicate with each other, It is implemented by a third-party route; there are two points to be noted for the division of vlan: one is to divide several different vlan groups, and each has a different vlan id number; the switch port assigned to the vlan group also has a port id. For example, ports 1, 2, 3, and 4 are divided into vlan10, 5, 6, 7, and 8 to vlan20. I can set the port id of ports 1, 3, and 4 to 10, and set the port id of port 2 to 20; set the port id of the 5, 6, and 7 ports to 20, and set the port id of the 8 port to 10. In this case, ports 1, 3, and 4 in vlan10 can communicate with port 8 of vlan20; and port 2 in vlan10 can communicate with ports 5, 6, and 7 in vlan20; although the vlan id is different, the port id is the same. , can communicate, the same vlan id is the same, the ports with different port id can not access each other, for example, the port 2 in vlan10 can not communicate with 1, 3, 4 ports.

Access and TRUNK

Simple, you think of the switch as a building.

Each household in the building is access, access can be configured with different IDs, for example, 10 households have 10 IDs; The elevator inside the building is a trunk. He is not a resident in the building, but he can transfer the residents of different IDs in the building to their respective rooms.

The main purpose of the trunk is to save the switch port. With one port, all the Vlans set on the switch can be transmitted.