VLAN database change vs VLAN configuration change

[DeanL01]

Dear experts

We know

1. VTP summary advertisements are sent every time a VLAN database change occurs. And

2. VTP subnet advertisements are sent after a VLAN configuration change occurs.

So could anyone kindly please explain the difference between "VLAN database change" and "VLAN configuration change"? Thanks a lot!

[Martin L]

One point is about vtp transparent mode which is stored in nvram config (sh run) while server and client modes are not stored in running config but placed into vlan.dat file.

I think adding or removing vlans is considered "VLAN configuration change" which will be pushed to VLAN database depending on vtp mode.  "VLAN database change" can be a change made by vtp protocol and not by admin.    

[paul driver · Accepted solution]

Hello
If you make a change to the vlan database then a Subset advertisement is sent, a Summary advertisment is periodic so this is sent even if nothing has changed in the vtp domain since the last summary was sent.

Summary advertisements are periodic sent every 300 seconds by the server or client switch into the vtp domain, within this update includes the vtp version, domain and configuration revision numbers for the vtp database.

Subset advertisements are sent after any specific change is made to any vlan(s) in the vtp domain

Two other advertisements exist ,

Requests  - Which can be sent by the switch to query the vtp server so it can update its own vtp database after the switch had received summary advertisement and sees in that advertisement more recent up to date information then it currently has.

Membership announcement - relates to vtp pruning, these messages tell a connected switch it is interested receiving traffic for a particular vlan and if it doesn’t receive any reply it will not send traffic for that specific vlan.