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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 9 Creating and Maintaining VLANs
Using the VLAN Trunking Protocol
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.
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 second
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