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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter9 Creating and Maintai nin g VLA Ns Using the VLAN Trunking Protocol
VTP Advertisements
Each switch in the VTP domain sends periodic global configuration advertis ements from each trunk port
to a reserved multicast address. Neighboring switches receive these advertisements and update their
VTP and VLAN configurations as necessary.
Note Because trunk ports send and receive VTP advertisements, you must ensure that at least one trunk
port is configured on the switch and that this trunk port is connected to the trunk port of a seco nd
switch. Otherwise, the switch cannot receive any VTP advertisements. For more information on
trunk ports, see the “Understanding VLAN Trunks” section on page 9-22.
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 (ISL and 802.1Q)
VLAN name
VLAN type
VLAN state
Additional VLAN configuration information specific to the VLAN type