The Modern NAC Alternative for Zero Trust Security

Most enterprises need both, because they control different things. NAC decides whether a device is allowed onto the network, authenticating it at the perimeter with 802.1X or RADIUS. Microsegmentation decides what that device is allowed to reach once it is on, enforcing identity-based least-privilege policy on east-west traffic. NAC is the front door; microsegmentation is the interior doors. Elisity enforces that east-west policy on the Catalyst, EX and Arista switches an organisation already operates, so it runs alongside an existing NAC deployment without changing its configuration. The two are complementary rather than substitutes, with one exception: devices that cannot run an 802.1X supplicant — infusion pumps, PLCs, HMIs, building automation — fall outside what NAC can meaningfully enforce, and microsegmentation is the control that still covers them.

NAC (Network Access Control) controls who gets on your network by authenticating devices at the perimeter using 802.1X or RADIUS. Microsegmentation controls what devices can communicate with after they’re on the network by enforcing identity-based policies at every connection point. While NAC provides perimeter security, microsegmentation prevents lateral movement, the attack vector used in 70% of successful breaches. Elisity’s identity-based microsegmentation runs alongside an existing NAC deployment without changes to that configuration, and deploys in 2 weeks against the 3-12 months typical of a traditional NAC implementation. It is not a replacement for device admission: the NAC keeps that job, and Elisity enforces what an admitted device may reach.

The NAC market is dominated by a handful of products, and the limitation described here is architectural rather than specific to any one of them. Cisco Identity Services Engine (ISE), often paired with Cisco TrustSec for segmentation, is the most widely deployed. Forescout is commonly chosen for agentless device visibility in healthcare and OT estates. Aruba ClearPass, Fortinet FortiNAC, Portnox and Genians serve similar roles across campus and mixed-vendor networks. All of them decide admission — whether a device is allowed onto the network — using 802.1X, RADIUS, MAB or profiling. None of them, by design, enforces least-privilege policy on east-west traffic once a device is admitted, and each depends on VLAN or ACL constructs to approximate segmentation.

Elisity is not a replacement for device admission. It enforces identity-based least-privilege policy on the access-layer switches an organisation already operates, which is the control these products leave open. It runs alongside an existing ISE, Forescout or ClearPass deployment without changes to that configuration, and it is also the control organisations adopt when a NAC or TrustSec rollout stalls on 802.1X complexity or on devices that cannot run a supplicant.

Cisco ISE specifically is compared job by job, with the alternatives for each, in our guide to Cisco ISE alternatives.

Traditional NAC deployments typically require 3-12 months involving hardware procurement, 802.1X configuration, VLAN redesigns, and multi-team coordination. Elisity's microsegmentation deploys in 2 weeks. We can turn your existing wired, wireless, and firewall infrastructure into enforcement points. Day 1 focuses on cloud provisioning and Virtual Edge software deployment. Day 2 enables visibility and first security least privilage access security policies. Within 1 week, you can achieve full policy enforcement across all sites—a 75% reduction in deployment time compared to legacy NAC approaches. 

NAC projects fail due to complexity, resource constraints, and scope creep. Enterprises struggle with 802.1X authentication issues, VLAN sprawl, ACL management at scale, and the need for 14+ FTEs across Security Ops, Network Engineering, and platform management teams. Integration challenges with heterogeneous infrastructure (mixing Cisco, Aruba, Juniper, Arista, Hirshmann) create deployment bottlenecks. Additionally, NAC only controls perimeter access—it doesn't prevent lateral movement once attackers authenticate, leaving organizations vulnerable despite the investment. 76% of enterprises using NAC report adoption has plateaued due to these operational challenges. 

Yes, Elisity’s microsegmentation complements existing NAC deployments. NAC handles authentication and initial network access, while Elisity enforces continuous identity-based policies that prevent lateral movement after devices authenticate. This layered approach maximizes your NAC investment while addressing its fundamental limitation, the lack of east-west traffic control. Organizations deploy Elisity alongside NAC solutions without replacing infrastructure, and the integration requires no changes to your NAC configuration. Elisity does not take over device admission, so the NAC keeps authenticating devices onto the network while Elisity governs what they may reach once they are on it.

Not as a like-for-like swap, because the two answer different questions and Elisity is not a replacement for device admission. What does happen is that a stalled NAC programme gets reconsidered, and that is worth doing when a rollout has run past six months, when operational cost exceeds 10 or more FTEs, or when the estate contains significant IoT and OT devices that cannot run an agent or a supplicant. Those devices are admitted by MAC Authentication Bypass, which authenticates a spoofable MAC address and says nothing about what the device may reach afterwards, so the east-west control is the one delivering the security outcome. In that situation the admission project can be scoped to what it does well rather than completed at any cost, and Elisity runs alongside whatever NAC remains. For a detailed comparison of solutions, see our guide to the best NAC for industrial and OT networks.

Traditional NAC total cost of ownership includes software licenses, hardware appliances, 14+ FTE operational staff, and 3-12 month deployment professional services. Enterprises typically spend $500K-$2M+ annually depending on scale. Elisity's microsegmentation reduces operational overhead by 75%, requiring only 2 FTEs for management, and deploys in weeks versus months—significantly lowering professional services costs. Elisity is cloud-delivered with no hardware requirements, eliminating capital expenditure on appliances. Organizations typically see ROI within 6-9 months through reduced staffing needs, faster deployment, and prevention of costly breach-related lateral movement (average breach cost: $4.45M).