4 - VLANs - In-Depth Trunking
Below shows how things were done in the years of hubs :oP - this is how the Native VLAN would play its part....
5 - VLANs - VLAN Trunking Protocol
VTP RUNS ON TRUNKS
vtp = not really trunking protocol, more like a replicating protocol
with revision numbers (the double edged sword)
sends VTP update with new revision
the switch updates its database and updated with new one
this is a great feature in a large scale network/campus, smaller networks ... well, lets go
over the bad ....
so you plug in your new ebay switch to config etc
when u connected the switch if it managed to negotiate a trunk, it will send its VTP out to the network, and as works switches database is on revision 3 and our new switch is on 1302....
it updates the others!
So now all the ports that were assigned to VLANs .... are gone! everything goes down :0(
(if a switchport is assigned to a vlan that does not exist the port light goes amber - test this)
So the admin/you will have to configure the VLANs again, then jump on all switches to assign ports to VLANs
although in real world, the VTP domain would have to match, also password if configured etc
SO USE WISELY
moda/password/pruning = under VTP config ...
VTP mode 1 = transparent mode = no pass through for boradcast, it is stopped
VTP mode 2 = transparent mode = allows VTP updates to pass through
show vtp status
Configuration Revision - IMPORTANT
VTP Domain Name - BE VERY CAREFUL WITH THIS, when this is null/empty it is in its most vunerable state
SO you dont even need password or domain password! to get the updates, it will auto config itself
to it ....... (sent in clear text also)
moral - hardcode switchports to accessports to stop this!!!
NULL = susceptible to VTP updates
although it says running version 2, notice it says version 1 is disabled, so ergo we are running version 1
6 - STP - Foundation Per-VLAN Spanning Tree Concepts 1
