交换-VLAN.ppt

* Slide 1 of 1 Purpose: Emphasize: Notes: VTP is a Cisco proprietray feature. VTP is a Layer 2 messaging protocol that maintains VLAN configuration consistency by managing the addition, deletion, and renaming of VLANs on a network-wide basis. VTP minimizes misconfigurations and configuration inconsistencies that can cause several problems, such as duplicate VLAN names, incorrect VLAN-type specifications, and security violations. A VTP domain (also called a VLAN management domain) is one switch or several interconnected switches sharing the same VTP domain. A switch is configured to be in only one VTP domain. You make global VLAN configuration changes for the domain by using the Cisco IOS command-line interface (CLI), Cisco Visual Switch Manager Software, or Simple Network Management Protocol (SNMP). By default, a 1900 switch is in the no-management-domain state until it receives an advertisement for a domain over a trunk link or you configure a management domain. The default VTP mode is server mode, but VLANs are not propagated over the network until a management domain name is specified or learned. If the switch receives a VTP advertisement over a trunk link, it inherits the management domain name and configuration revision number. The switch then ignores advertisements with a different management domain name or an earlier configuration revision number. When you make a change to the VLAN configuration on a VTP server, the change is propagated to all switches in the VTP domain. VTP advertisements are transmitted out all trunk connections, including Inter-Switch Link (ISL), IEEE 802.1Q, IEEE 802.10, and ATM LAN Emulation (LANE). If you configure a switch from VTP transparent mode, you can create and modify VLANs, but the changes are not transmitted to other switches in the domain, and they affect only the individual switch. 如果有很多VLAN并覆盖多个交换机，手工在每台交换机上配置VLAN是件很麻烦的事。VTP是Cisco的私有协议，工作在第2层，通过管理整个网络上的VLAN增加、删除和改名来维护VLAN配置的一致性。在主干接口上，VTP交换机每300秒向默认的管理域VLAN1发一次总结性公告。