VTP
domain
defines a set of interconnected switches sharing the same
VTP configuration.
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VTP Modes
Mode
Description
Client
•
Cannot create, change, or delete VLANs on command-line interface
(CLI).
•
Forwards advertisements to other switches.
•
Synchronizes VLAN configuration with latest information received from
other switches in the management domain.
•
Does not save VLAN configuration in nonvolatile RAM (NVRAM).
Server
•
Can create, modify, and delete VLANs.
•
Sends and forwards advertisements to other switches.
•
Synchronizes VLAN configuration with latest information received from
other
switches in the management domain.
•
Saves VLAN configuration in NVRAM.
Transparent
•
Can create, modify, and delete VLANs only on the local switch.
•
Forwards VTP advertisements received from other switches in the same
management domain.
•
Does not synchronize its VLAN configuration with information received
from other switches in the management domain.
•
Saves VLAN configuration in NVRAM.
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VTP Operation
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VTP Pruning
VTP pruning prevents flooded traffic from propagating to switches that do not
have members in specific VLANs.
VTP pruning uses VLAN advertisements to determine when a trunk connection
is flooding traffic needlessly. Switches 1 and 4 in the figure support ports
statically configured in the Red VLAN.
The broadcast traffic from Station A is not forwarded to Switches 3, 5, and 6
because traffic for the Red VLAN has been pruned on the links indicated on
Switches 2 and 4.
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VTP Versions
Three
VTP versions: V1, V2, V3.
Versions are not interoperable (e.g., V2 supports token ring VLANs but
V1 does not).
Unrecognized
Type-Length-Value (TLV)
configuration changes are
propagated by V2 servers and clients and these unrecognized TLVs can
be stored in NVRAM.
V1 transparent switches inspect VTP messages for the domain name
and version and forward a message only if the version and domain
name match. V2 transparent switches forward VTP messages in
transparent mode without checking versions.
V2 performs VLAN consistency checks (VLAN names and values) only
when you enter new information through the CLI or via SNMP. V2 does
not perform checks when new information is obtained from a VTP
message or when information is read from NVRAM. If the MD5 hash on
a received VTP message is correct, V2 accepts the VTP message
information.
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VTP Version 1 and 2
Version-dependent transparent mode
•
VTP Version 1, a VTP transparent network device inspects VTP
messages for the domain name and version
•
VTP Version 2 forwards VTP messages in transparent mode, without
checking the version.
