Implementation of 802.1Q VLAN protocol and 802.1P protocol

Implementation of 802.1Q VLAN protocol and 802.1P protocol

Abstract: This article mainly introduces the implementation of the 802.1Q VLAN protocol in Ethernet switches and some basic contents of the 802.1p protocol. For specific details of the implementation of these two protocols, refer to the relevant information of the 802.1Q and 802.1p protocols. The 802.1Q protocol
The 802.1Q protocol, the Virtual Bridged Local Area Networks protocol, mainly stipulates the realization of VLANs. Let ’s first talk about the basic concepts about VLANs
Virtual LANs are developing rapidly. The major large network manufacturers in the world have implemented the VLAN protocol in their switch equipment. As the name suggests, VLAN is a virtual local area network. For example, for our Quidway S2403 switch, it can use 24 of them.
The 10M Ethernet port is divided into several groups, such as protocol group ATM group test group, etc. Each user in this group is like the same local area network (probably the users of the protocol group are located on many switches instead of one switch). The users of the group cannot access the members of this group. In fact, the definition of VLAN members can be divided into 4 types:
1 Divide VLANs according to ports
1 This method of dividing VLAN is based on the port of the Ethernet switch. For example, the 1 ~ 4 port of S2403 is VLAN A
5 ~ 17 is VLAN B 18 ~ 24 is VLAN C. Of course, these ports belonging to the same VLAN can be discontinuous. How to configure is determined by the administrator. If there are multiple switches, for example, you can specify ports 1 ~ 6 of switch 1 and 1 ~ of switch 2. 4 ports are the same
VLAN, that is, the same VLAN can span several Ethernet switches according to port division is currently the most commonly used method to define VLAN
The IEEE 802.1Q protocol specifies how to divide VLANs according to the ports of the switch. The advantage of this division method is to define
VLAN membership is very simple as long as all the ports are defined. The disadvantage is that if the user of VLAN A leaves the original port to a port of a new switch, then it must be redefined
2 Divide VLAN according to MAC address
This method of dividing VLAN is based on the MAC address of each host, that is, each host with a MAC address is configured to which group he belongs to. The biggest advantage of this method of dividing VLAN is that when the user's physical location moves, it is from a switch The VLAN does not need to be reconfigured when switching to another switch, so it can be considered that this method of dividing based on MAC address is based on the user's VLAN
The disadvantage of this method is that all users must be configured during initialization. If there are hundreds or even thousands of users, the configuration is very tiring and this division method also leads to a reduction in the efficiency of the switch because each switch There may be many members of the VLAN group on the port, so it is impossible to limit the broadcast package. In addition, for users who use laptops, their network cards may be frequently changed so that the VLAN must be constantly configured.
3 Divide VLANs according to the network layer
This method of dividing VLANs is based on each host's network layer address or protocol type (if multiple protocols are supported). Although this division method may be based on network addresses such as IP addresses, it is not a route. Do not confuse it with network layer routing. It looks though
2 The IP address of each data packet, but because it is not a route, there is no routing protocol such as RIP OSPF but bridge exchange based on the spanning tree algorithm. The advantage of this method is that the physical location of the user does not need to be reconfigured. Divide VLANs according to protocol type. This is very important for network managers. This method also does not require additional frame tags to identify VLANs.
This can reduce the network traffic. The disadvantage of this method is efficiency because it is time-consuming to check the network layer address of each packet (compared to the previous two methods). The general switch chip can automatically check the ether of the packet on the network. Net frame header, but to make the chip check the IP frame header requires higher technology and is more time-consuming. Of course, this also depends on the implementation method of each manufacturer
4 IP multicast as a VLAN
IP multicast is actually a definition of VLAN, which means that a multicast group is a VLAN.
The VLAN is extended to the WAN, so this method has more flexibility and it is also easy to expand through the router. Of course, this method is not suitable for LANs. It is mainly inefficient. Multicast for LANs has a Layer 2 multicast protocol GMRP
It can be seen from the above that various VLAN definition methods have their own advantages and disadvantages, so many manufacturers' switches have implemented more than one method so that network managers can choose according to their actual needs. Many other manufacturers are implementing
When considering the complexity of VLAN configuration, it also provides a certain degree of automatic configuration and convenient network management tools
3 It can be said that VLANs do not have their own standards. Previously, various manufacturers claimed that their switches implemented VLANs, but the methods implemented by various manufacturers were different, so they could not interconnect with each other. Once users bought a switch from a certain manufacturer, they could not buy Other manufacturers have used CISCO's previous switches to implement VLAN through 802.10 protocol and ISL. Now IEEE has proposed
The 802.1Q protocol is being reviewed and will be determined as a standard in the near future. Currently, various manufacturers are also implementing this protocol. CISCO has implemented the 802.1Q protocol in its IOS 12.0

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