Vtp And Switch Stacks; Configuring Vtp - Cisco Catalyst 2975 Software Configuration Manual

Chapter 15

Configuring VTP

Figure 15-2
Switch E
Switch F
Enabling VTP pruning on a VTP server enables pruning for the entire management domain. Making
VLANs pruning-eligible or pruning-ineligible affects pruning eligibility for those VLANs on that trunk
only (not on all switches in the VTP domain).
See the
you enable it. VTP pruning does not prune traffic from VLANs that are pruning-ineligible. VLAN 1 and
VLANs 1002 to 1005 are always pruning-ineligible; traffic from these VLANs cannot be pruned.
Extended-range VLANs (VLAN IDs higher than 1005) are also pruning-ineligible.
VTP pruning is not designed to function in VTP transparent mode. If one or more switches in the
network are in VTP transparent mode, you should do one of these:
•
•
To configure VTP pruning on an interface, use the switchport trunk pruning vlan interface
configuration command (see the
pruning operates when an interface is trunking. You can set VLAN pruning-eligibility, whether or not
VTP pruning is enabled for the VTP domain, whether or not any given VLAN exists, and whether or not
the interface is currently trunking.

VTP and Switch Stacks

VTP configuration is the same in all members of a switch stack. When the switch stack is in VTP server
or client mode, all switches in the stack carry the same VTP configuration. When VTP mode is
transparent or off, the stack is not taking part in VTP.
•
•
•
VTP version 3 functions the same on a standalone switch or a stack except when the switch stack is the
primary server for the VTP database. In this case, the MAC address of the stack master is used as the
primary server ID. If the master switch reloads or is powered off, a new stack master is elected.
OL-19720-02
Optimized Flooded Traffic with VTP Pruning
Switch D
Flooded traffic
is pruned. Port
4
Flooded traffic
Port
is pruned.
5
Switch C
"Enabling VTP Pruning" section on page
Turn off VTP pruning in the entire network.
Turn off VTP pruning by making all VLANs on the trunk of the switch upstream to the VTP
transparent switch pruning ineligible.
When a switch joins the stack, it inherits the VTP and VLAN properties of the stack master.
All VTP updates are carried across the stack.
When VTP mode is changed in a switch in the stack, the other switches in the stack also change VTP
mode, and the switch VLAN database remains consistent.
Port 2
Switch B
Red
VLAN
Port 1
Switch A
15-15. VTP pruning takes effect several seconds after
"Changing the Pruning-Eligible List" section on page
Catalyst 2975 Switch Software Configuration Guide
Understanding VTP
13-18). VTP
15-7