Understanding Vtp Modes - Cisco Catalyst 4500 Series Configuration Manual

Chapter 15 Configuring VLANs, VTP, and VMPS

Understanding VTP Modes

You can configure a Catalyst 4500 series switch to operate in any one of these VTP modes:
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Catalyst 4500 series switches automatically change from VTP server mode to VTP client mode if the
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switch detects a failure while writing configuration to NVRAM. If this happens, the switch cannot be
returned to VTP server mode until the NVRAM is functioning.
Understanding VTP Advertisements
Each network device in the VTP domain sends periodic advertisements out each trunking LAN interface
to a reserved multicast address. VTP advertisements are received by neighboring network devices, which
update their VTP and VLAN configurations as necessary.
The following global configuration information is distributed in VTP advertisements:
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Understanding VTP Versions
VTP Version 2
If you use VTP in your network, you must decide whether to use VTP version 2 or version 3.
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Server—In VTP server mode, you can create, modify, and delete VLANs and specify other
configuration parameters (such as VTP version and VTP pruning) for the entire VTP domain. VTP
servers advertise their VLAN configuration to other network devices in the same VTP domain and
synchronize their VLAN configuration with other network devices based on advertisements received
over trunk links. VTP server is the default mode.
In VTP version 3, manipulation of VLANs can be done only to primary servers.
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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 network devices do not participate in VTP. A VTP transparent
network device does not advertise its VLAN configuration and does not synchronize its VLAN
configuration based on received advertisements. However, in VTP version 2, transparent network
devices do forward VTP advertisements that they receive on their trunking LAN interfaces.
Off—In VTP off mode, a network device functions in the same manner as a VTP transparent device
except that it does not forward VTP advertisements.
VLAN IDs (ISL and 802.1Q)
Emulated LAN names (for ATM LANE)
802.10 SAID values (FDDI)
VTP domain name
VTP configuration revision number
VLAN configuration, including maximum transmission unit (MTU) size for each VLAN
Frame format
Software Configuration Guide—Release IOS XE 3.3.0SG and IOS 15.1(1)SG
VLAN Trunking Protocol
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