VLANs absolutely can be considered security boundary. Sure, you can misconfigure switch and expose something unintentionally. But as a technology VLANs are pret

VLANs absolutely can be considered security boundary. Sure, you can misconfigure switch and expose something unintentionally. But as a technology VLANs are pretty battle-hardened. Random reddit discussion on the topic https://www.reddit.com/r/networking/comments/opmjol/vlan_segmentation_as_security_do_you_trust_it/ https://www.reddit.com/r/networking/comments/opmjol/vlan_seg... That BH presentation is 20 years old now, and almost completely Cisco specific. I would not make security decisions on such data alone.