Cisco NM-8B-U User Guide - Page 6
VTP Domain, VTP Modes, VTP Advertisements
UPC - 074632001001
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Feature Overview 16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series VTP Domain A VTP domain (also called a VLAN management domain) is made up of one or more interconnected switches that share the same VTP domain name. A switch can be configured to be in one and only one VTP domain. You make global VLAN configuration changes for the domain using either the command-line interface (CLI) or Simple Network Management Protocol (SNMP). By default, the switch is in VTP server mode and is in an un-named domain state until the switch receives an advertisement for a domain over a trunk link or until you configure a management domain. You cannot create or modify VLANs on a VTP server until the 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 the VTP configuration revision number. The switch ignores advertisements with a different management domain name or an earlier configuration revision number. If you configure the switch as VTP transparent, you can create and modify VLANs but the changes affect only the individual switch. 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 using IEEE 802.1Q encapsulation. VTP maps VLANs dynamically across multiple LAN types with unique names and internal index associations. Mapping eliminates excessive device administration required from network administrators. VTP Modes You can configure a switch to operate in any one of these VTP modes: • Server-In VTP server mode, you can create, modify, and delete VLANs and specify other configuration parameters (such as VTP version) for the entire VTP domain. VTP servers advertise their VLAN configuration to other switches in the same VTP domain and synchronize their VLAN configuration with other switches based on advertisements received over trunk links. VTP server is the default mode. • Client-VTP clients behave the same way as VTP servers, but you cannot create, change, or delete VLANs on a VTP client. • Transparent-VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on received advertisements. However, in VTP version 2, transparent switches do forward VTP advertisements that they receive out their trunk interfaces. VTP Advertisements Each switch in the VTP domain sends periodic advertisements out each trunk interface to a reserved multicast address. VTP advertisements are received by neighboring switches, which update their VTP and VLAN configurations as necessary. The following global configuration information is distributed in VTP advertisements: • VLAN IDs (801.Q) • VTP domain name • VTP configuration revision number • VLAN configuration, including maximum transmission unit (MTU) size for each VLAN • Frame format Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ 6