A vlan is a broadast domain as you say but it is not necessarily reduced because it depends on how many devices you have in that vlan. But is it is virtual in the sense that a vlan can span multiple switches or even sites whereas before vlans devices were constrained to the same physical location if they were on the same subnet.
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A VLAN is what it's named, a Virtual LAN. Basically, it allows multiple logical LAN (separate L2 network segments - i.e. your broadcast domain) to run side-by-side on the same physical switch (rather than separate physical LAN segments on different physical switches). As Jon noted, per se, it doesn't mean such must be smaller, but as it can be done logically, often implementations are "smaller" because we don't need to find and connect multiple physical switches. For example, one VLAN capable 48 port switch might support 24 VLANs each containing just 2 ports, avoiding the need of using 24 physical switches for the same L2 isolation.
BTW, some newer switches have special VLAN capabilities, such a PVLANs (private VLANS) that wouldn't be easy to define with physical switches.
No you can't really because a vlan can exist across multiple switches.
This would be my definition but others may have better ones -
A vlan is a logical grouping of end devices into the same L2 broadcast domain (LAN) even though those devices may be located on multiple different switches which may or may not be in the same physical location.
I see what you mean now. I thought you were talking about a single physical switch.
But in my opinion referring to a vlan as switch is missing the point. A vlan is primarily a L2 broadcast domain that is simply logical in terms of where the end devices are connected rather than physical. This says nothing about how may vlans you have per switch.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...