It would be interesting if you could cover Avaya's Fabric Connect networking technology that can help speed network implementation which have a large number of network cameras. (P.S. my current company is also an Avaya Platinum partner)
One of the reasons VLANs are often seen as restricting or allocating bandwidth is because they are often used in conjunction with quality of service. QoS may be set by VLAN in most managed switches. A surveillance VLAN, for example, may receive higher priority as a whole than general data or voice VLANs.
If the surveillance VLAN consists of a static group of ports on a non-blocking switch, how would having a higher priority improve its performance over the voice VLAN, also with its own discrete non-blocking ports?
Great question and also the most common argument for not implementing QoS.
Congestion, (#2). If you do check out this link please keep in mind (not mentioned in the linked article) that we will have other devices connected to the switch, devices that possibly consume much more bandwidth /resources than IP cameras. There may also be access or distribution switches connected to distribution or core switches, and the network congestion will be exacerbated by the aggregate traffic from the devices connected to those feeder switches. At some point our network will experience data burst / congestion / etc & we want to decide how traffic is handled.
I've installed POS equipment and networking equipment for several of the largest retailers and they all used VLANs to separate their POS equipment. All of them had specific ports that the POS equipment needed to be connected to.
It depends on the switches and routers in the network. Layer 3 switches can route between VLANs, or if using layer 2 switches, the router will route all interVLAN traffic. Depending on the brand and capabilities of the equipment, you can grant access between VLANs via firewall rules or ACLs.