ccna change

ccna change.8.1 Overview of VLANs8.1.1 Introduction to VLANsThe switch can isolate the conflict domain, however, it cannot isolate the broadcast domain. All computers connected together through multiple switches are in a broadcast domain, and any computer that sends a broadcast packet will be received by all other computers.Virtual Local Area Network ( VirtualLocal Area Network, VLAN) is the technology of virtual workgroup by dividing the physical switch ports into a logical group of devices or users through software function, these devices and users are not limited by the physical network segment, they can be organized according to the function, department and application and other factors. A VLAN is a broadcast domain, and the communication between VLANs must be realized through the Layer 3 routing function, compared with the traditional LAN technology, VLAN technology is Compared with traditional LAN technology, VLAN technology is more flexible and efficient, with the advantages of enhancing network security, reducing costs, improving network performance, reducing the size of the broadcast domain, improving management efficiency, and simplifying project management and application management.VLANs on Cisco switches are divided into normal VLANs and extended VLANs with a VLAN ID range of 1.4094. normal VLANs are used in small and medium business networks and enterprise networks with a VLAN ID range of 1.1005, with 1002.1005 reserved for token ring VLANs and FDDIVLANs. VLAN1 and VLANs 1002-1005 are created automatically and cannot be deleted. Common VLAN information is stored in a VLAN database file called vlan.dat, which is located in the switch's Flash. VTP (VLANTrunk Protocol) can only recognize common range VLANs. extended VLANs allow service providers to expand their infrastructure to accommodate more customers. Some enterprises are large enough to require the use of extended range VLANIDs, which range from 1006.4094. extended VLANs support fewer VLAN features than regular VLANs. Extended VLAN information is stored in the operational configuration file. VTP (versions 1 and 2) does not recognize extended VLANs.8.1.2 VLAN Types VLAN types can be defined by traffic class or by specific functions. common VLAN types are described below.Chapter 8 VLANs, Trunk, and Inter-VLAN Routing . 103 .Data VLAN: Used to transport user data traffic.Default VLAN: After the switch loads the default configuration for initial startup, all switch ports become the default VLANmembers. The default VLAN for Cisco switches is VLAN1,which cannot be renamed or deleted.