what is the difference between normal creation of vlans<e.g vlan 10 name sales? & the SVIs Interface;is SVI's do ROUTING Between vlans without Vlans creation First
As Michael said an SVI is the layer 3 routed interface for a layer 2 vlan. It does not have to be on the same switch as the vlan was created on although more often than not they are. The layer 2 vlan can exist across many layer 2 switches but you only have one SVI for that vlan (or 2 + HSRP etc.)
You should create the layer 2 vlan first before you create the SVI.
SVI is a layer 3 logical interface that you create on the VLAN to enable routing for the vlan or Managing the vlan.If you dont create an SVI on a lyer3 capable device, it will be only a pure layer2 vlan and you will need an external router/routing device to do the inter-vlan routing for you.
When you have a Layer 3 device, you can directly create logical Layer3 interfaces on it i.e SVI to enable routing for the vlans.Depending on the switch you are using, you might have to enable "IP routing" on the switch to enable inter-vlan routing among the vlans.