VTP Advertisements
Each switch in the VTP domain sends periodic global configuration advertisements from each trunk port to
a reserved multicast address. Neighboring switches receive these advertisements and update their VTP and
VLAN configurations as necessary.
Because trunk ports send and receive VTP advertisements, you must ensure that at least one trunk port is
configured on the switch stack and that this trunk port is connected to the trunk port of another switch.
Otherwise, the switch cannot receive any VTP advertisements.
VTP advertisements distribute this global domain information:
•
VTP domain name
•
VTP configuration revision number
•
Update identity and update timestamp
•
MD5 digest VLAN configuration, including maximum transmission unit (MTU) size for each VLAN
•
Frame format
VTP advertisements distribute this VLAN information for each configured VLAN:
•
VLAN IDs (including IEEE 802.1Q)
•
VLAN name
•
VLAN type
•
VLAN state
•
Additional VLAN configuration information specific to the VLAN type
In VTP version 3, VTP advertisements also include the primary server ID, an instance number, and a start
index.
Related Topics
Prerequisites for VTP
VTP Version 2
If you use VTP in your network, you must decide which version of VTP to use. By default, VTP operates in
version 1.
VTP version 2 supports these features that are not supported in version 1:
• Token Ring support—VTP version 2 supports Token Ring Bridge Relay Function (TrBRF) and Token
Ring Concentrator Relay Function (TrCRF) VLANs.
• Unrecognized Type-Length-Value (TLV) support—A VTP server or client propagates configuration
changes to its other trunks, even for TLVs it is not able to parse. The unrecognized TLV is saved in
NVRAM when the switch is operating in VTP server mode.
• Version-Dependent Transparent Mode—In VTP version 1, a VTP transparent switch inspects VTP
messages for the domain name and version and forwards a message only if the version and domain name
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
2087
Information About VTP
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