Voice VLAN concept and networking

Voice VLAN concept and networking concept: the so-called voice vlan uses vlan to identify a packet as a Voice packet, and the packet carries voice data. In networks where voice messages and data packets coexist, vlan-based voice packets are identified to distinguish voice messages and data packets, and a higher priority is given to voice packets to ensure that voice data is preferentially served, low latency and low packet loss rate. Networking scenario: Generally, a voice device (usually an ip Phone) has two Ethernet interfaces. An Ethernet interface of an ip Phone connects to the Ethernet interface of the access switch, another Ethernet interface of the ip Phone connects to the computer's Ethernet interface. In this way, the same interface of the vswitch has both the voice packets of the ip phone and the data packets of the computer. In another case, the ip phone and computer are connected to the same hub, and the hub is connected to the switch. But now interactive Ethernet switches are very cheap, and 20 or 30 vswitches with five ports can be purchased. There is no need to use hubs to expand Ethernet, no hub is found on the market. If the computer and ip phone are connected to different interfaces of the switch, in principle, the voice packets can be identified based on the port, and the packets are tagged with the PVID of the port, and mark it with a higher priority. However, the voice tag method described below is flexible. At the same time, ip phones and computers are often together (on the office space), while switches are at a certain distance from the office space. In this way, it is a waste of wiring resources and switch interface resources to determine the voice vlan: currently, there are mainly two voice tag-based methods. 1. voice devices that support tags, such as ip Phone-sent/received packets, support tags, in this way, the voice device attaches the voice tag to the packet when sending the packet. After the switch receives the packet, it compares the vlan configured by the packet with the voice vlan configured by the interface. If the packet vlan is a voice vlan, the packet is given a higher priority and then forwarded. So how does the ip phone know what tag should be added to the sent packet so that the vlan of the packet is the voice vlan configured for the interface connected to it? This is achieved through the LLDP protocol. The ip Phone Number communicates with the switch through LLDP. The switch sends the voice vlan of the interface to the ip phone number through LLDP protocol. 2. The voice device that does not support tags, for example, Huawei's EchoLife ET65 ip phone sends/receives packets without tags. In this case, the OUI field of the mac address of the ip phone is used for identification. In fact, vlan is divided based on the mac address. Because the mac address of the device is determined when the device leaves the factory, the OUI field is allocated to a vendor, then, based on the OUI field of the source MAC address of the packet, we can know that the packet is generated by the ip phone of the vendor. After the switch receives the packet, vlan the packets based on the OUI of the MAC address of the source packet, it also identifies a high-priority H3C switch with the default voice vlan OUI address no. OUI address manufacturer 1 0003-6b00-0000 Cisco phone 2 000f-e200-0000 H3C aolympus NK phone 3 rjpingtel phone 4 00e0-7500-0000 Polycom phone 5 00e0-bb00-0000 3Com phone