For most businesses, remote access still means a VPN — a client installed on a laptop, a tunnel into the corporate network, and from there, roughly the same access an employee would have sitting at a desk in the office. That model made sense when remote work was the exception. It’s a much weaker model now that it’s often the default, and it’s exactly what SASE was built to replace.
How Traditional VPN Access Works
A VPN client authenticates a user, establishes an encrypted tunnel, and then routes traffic into the internal network. Once connected, the user typically has broad reachability across whatever internal systems their credentials theoretically permit — not because anyone explicitly designed it that way, but because VPNs operate at the network layer, not the application layer. Segmenting access more granularly requires additional firewall rules and ongoing maintenance that most IT teams don’t have the bandwidth to keep current.
The core weakness: if a VPN credential is compromised (phishing remains the most common cause), the attacker inherits that same broad network-layer reach.
How SASE Access Works Instead
SASE (Secure Access Service Edge) replaces network-level VPN tunnels with application-specific access brokered through Zero Trust Network Access (ZTNA). Instead of connecting a user to the network, ZTNA connects a user to one specific application, after evaluating identity, device posture, and context for that specific request — and it re-evaluates continuously, not just once at login.
Practically, this means a compromised credential grants access to the single application that session was scoped for, not a tunnel into everything else sitting on the network.
Beyond Access: SASE Converges More Than VPN Replacement
ZTNA is one piece of a broader SASE platform, which typically also includes SD-WAN (optimized branch connectivity), a Secure Web Gateway (inspecting outbound web traffic for threats), Firewall-as-a-Service (cloud-delivered firewall policy instead of per-site hardware), and a Cloud Access Security Broker (visibility and control over SaaS application usage). Traditional VPN solves exactly one problem — remote connectivity. SASE addresses the same problem as one piece of a converged security and networking platform.
Performance Is Also Part of the Story
VPNs frequently backhaul all traffic through a central data center even when the destination is a cloud application the user could otherwise reach directly — adding latency for no security benefit. SASE platforms, being cloud-delivered and distributed globally, generally route traffic more directly, which in practice often makes the switch a performance upgrade as well as a security one, not a trade-off between the two.
Is This a Rip-and-Replace Project?
Not necessarily, and it shouldn’t be treated as one. A responsible migration typically pilots ZTNA with a small group before retiring VPN entirely, validates that application access policies actually match how people work day to day, and rolls out in phases rather than a single cutover weekend. The goal is replacing the access model without a week of help-desk tickets from people who suddenly can’t reach what they need.
Where This Fits Into a Broader Zero Trust Strategy
VPN replacement is often the most visible and immediately valuable piece of a Zero Trust and SASE engagement, but it’s one component within a larger architecture. Our sample Zero Trust & SASE roadmap shows how ZTNA fits alongside the other four SASE components in a phased deployment plan.