Five switches are interconnected on a LAN which have multiple VLANs and are all part of the same VTP domain.
Clarification One How do we know from the information on "SWT - C" that which switches are acting as or deployed as a Server of the VTP Domain.
----- The command "show vtp status" will show your VTP server if you only have one VTP server in your VTP domain. I am not aware of any good way to determine all of the VTP servers of a VTP domain. I am not certian that there is a known way short of tracking the VTP updates over time. The last VTP server which provided an update will be listed, but I do not believe that a complete list of all VTP servers in a domain can be found without viewing all of the configuration commands of the switches. There are three VTP show commands on a common Cisco ethernet switch: Cisco6509#show vtp ? counters VTP statistics password VTP password status VTP domain status
The output of "show vtp status" is included at the end of this message. The output of "show vtp counters" is included at the end of this message. There can be more than one VTP server in a VTP domain. Recall the practice test question about how a newly configured switch is added to the network and LAN connectivity is lost because by default a switch is a VTP server? This is an example of multiple VTP servers in a VTP domain. VTP clients listend to VTP messages while VTP servers both listen and source VTP messages. Multiple VTP servers can exist on a VTP domain. Multiple VTP domains can overlap managing of the same VLANs. In the situation presented, switch SWT-A could be a server of VTP domain wally and switch SWT-B could be a server of VTP domain world. VTP domain wally has VLANs 1, 2, and 3. VTP domain world has VLANs 1, 2, and 5. Switch SWT-C, a client of VTP domain wally, has VLANs 1, 2, and 3. Switch SWT-D, a client of VTP domain world, has VLANs 1, 2, and 5. When switch SWT-A of VTP domain wally removes VLAN 3, switch SWT-C removes VLAN 3 while switches SWT-B and SWT-D do nothing. If all of these switches were part of the same VTP domain, even with both SWT-A and SWT-B being servers, the removal of VLAN information from one server will result in the removal of the VLAN from other server and the clients.
Clarification Two Suppose One "VTP Server Switch" is disconnected from the domain for 20 minutes and then reconnect again back, in the 20 minute period what happens to the VLANS on the Domain as a whole.
----- If the VTP server was removed from the network and then reconnected without powering off, the VTP clients and their VLANs remain unaffected. If the VTP server rejoins the network after a restart, its VTP update revision number will be lower than the last update received by the clients. Change a client to server mode, make a VLAN change, and then it change back to client mode. This will send a recent revision number update which the actual VTP server will receive and continue from in its own updates. From that point on, the VTP updates from the real VTP server will match the next expected revision of the VTP clients.
Cisco6509#show vtp status VTP Version : 2 Configuration Revision : 11 Maximum VLANs supported locally : 1005 Number of existing VLANs : 25 VTP Operating Mode : Server VTP Domain Name : CiscoLAN VTP Pruning Mode : Enabled VTP V2 Mode : Disabled VTP Traps Generation : Disabled MD5 digest : 0x45 0x32 0xBC 0x9B 0xDB 0x43 0xED 0x6B Configuration last modified by 192.168.1.150 at 6-6-06 7:06:00 Local updater ID is 192.168.1.20 on interface Vl1 (lowest numbered VLAN interface found)
Cisco6509#show vtp counters VTP statistics: Summary advertisements received : 187562 Subset advertisements received : 106 Request advertisements received : 4 Summary advertisements transmitted : 265379 Subset advertisements transmitted : 135 Request advertisements transmitted : 0 Number of config revision errors : 0 Number of config digest errors : 0 Number of V1 summary errors : 0
VTP pruning statistics:
Trunk Join Transmitted Join Received Summary advts received from non-pruning-capable device
---------------- ---------------- ---------------- --------------------------- Gi1/1 1018856 1018843 0 Gi1/2 3690991 3690856 0 Gi1/3 996436 996413 0 Gi1/4 1019050 1019038 0 Gi1/5 3690961 0 0 Gi1/6 1018553 1018544 0