Last Updated on August 1, 2021 by Admin 2
A new switch that contains a configuration consisting of only VLAN 5 was just added to the network. Now users assigned to VLANs 9 and 10 are complaining of communication problems.
Using the show vlan command, you discover that only VLAN 5 and the default VLANs exist on all your switches.
What could have caused this problem?
- The new switch had the default password set.
- The domain name on the new switch did not match the rest of the network.
- The new switch was configured in server mode and the revision number was lower than the current number in the network.
- The new switch was configured in server mode and the revision number was higher than the current number in the network.
- The new switch was configured in transparent mode and the revision number was higher than the current number in the network.
Adding a switch that is configured in VTP server mode and has a revision number higher than the current number in the network could cause the communication problem in the scenario. If the new switch was configured in server mode and the revision number was higher than the revision number on existing switches, it could cause the rest of the switches to update with the information contained in that new advertisement.
VTP advertisements are flooded throughout the management domain every five minutes or whenever a change occurs in the network. These advertisements are originated from a switch that is in server mode, and are propagated by switches that are in either client or transparent mode. Before a client or another server accepts or incorporates the information sent in the advertisement, it checks the domain name and password (if defined) against its own configuration. Next, the revision number is checked to see if it is higher than the last value stored in the receiving switch. If the revision number is higher, the receiving switch will overwrite its VLAN database with the information in the advertisement.
A VTP switch in transparent mode will receive and forward VTP advertisements. It will not use the contents of the advertisement to synchronize with its own VLAN database.
The password, domain name, and VTP mode will not cause the switch to overwrite the other switches. This is a revision number issue.
Layer 2 Technologies
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