Updated: May 20, 2025
Lock the Hallways, Not Just the Doors
Most enterprises have done the easy part. They’ve added multi-factor authentication. They’ve implemented basic NAC. Some even use SASE to manage external access.
But once someone is inside, the story changes.
Flat networks still dominate. VLANs span across buildings. Access switches treat all endpoints the same. A developer laptop and a CCTV camera share the infrastructure. Lateral movement becomes trivial.
Zero Trust doesn’t just demand that you verify identity. It requires you to restrict access based on identity, context, and behaviour, even after entry. That’s what micro-segmentation does. And that’s what Cisco ISE and SD-Access enable.
Why Firewalls Can’t Do It Alone
Perimeter firewalls were never designed to handle internal segmentation at scale. Once traffic is inside the trusted zone, traditional ACLs and VLAN isolation lose granularity.
In multi-site networks across cities like Mumbai, Pune, and Hyderabad, firewalls become bottlenecks.
Every microservice, every IoT sensor, every remote user increases complexity. Trying to manage this with static IP lists and port rules is not only error-prone, but it’s operationally unsustainable. What you need is a dynamic, identity-driven policy model.
Cisco ISE: Identity as the Policy Engine
Cisco Identity Services Engine (ISE) serves as the central intelligence layer. ISE classifies endpoints, verifies posture, applies policies, and tags users and devices with Scalable Group Tags (SGTs). These tags define access rights and feed into the enforcement fabric.
For example:
ISE doesn’t rely on IP addresses. It links policy to identity, device state, and location. When an endpoint fails compliance, ISE can automatically revoke access or reassign it to a remediation segment.
Cisco SD-Access: Policy Embedded in the Network
Cisco Software-Defined Access (SD-Access) provides the enforcement layer. Built on VXLAN and LISP, SD-Access separates identity from IP. It applies group-based policies directly into the fabric. You define what each group can access, and the network enforces it.
There is no need to manage VLAN sprawl. No need to push ACLs to every switch. Policies are defined once and enforced dynamically. This model supports:
A Manufacturing Story from Baddi, Himachal Pradesh
A process-heavy manufacturing firm in Baddi had OT systems connected over unmanaged switches. Office IT and industrial control systems shared the same VLAN.
One malware-laden USB stick from a contractor laptop triggered a chain of infections. Downtime followed. So did penalties.
Proactive Data Systems deployed Cisco ISE to classify devices and apply context-based policies. SD-Access was used to enforce segmentation at the fabric level. The network now restricts OT traffic to its own domain, blocks internet access for PLCs, and dynamically isolates any suspicious endpoint.
No change to application logic. No forklift upgrades. Just a smarter use of identity and policy.
What Most Security Architectures Miss
Zero Trust is widely discussed. But most implementations stop at perimeter authentication and VPN segmentation.
That’s not Zero Trust. That’s access control.
Micro-segmentation adds what most networks lack: persistent, internal enforcement. With ISE and SD-Access, segmentation adapts to changing user roles, device posture, and location. The network responds to identity, not just packets.
Performance and Policy, Not Trade-offs
Legacy segmentation often came at a cost: performance degradation, high operational overhead, or user frustration.
ISE and SD-Access remove those trade-offs by:
Your security posture improves. Your user experience doesn’t suffer.
The Big Picture, in Numbers
According to Cisco’s 2024 Security Outcomes Report, enterprises that adopt identity-based segmentation reduce lateral movement success rates by 74 per cent.
Gartner’s 2023 Market Guide for Zero Trust Network Access states that traditional NAC is insufficient without integrated segmentation enforcement.
How Proactive Data Systems Makes It Real
Deploying Cisco ISE and SD-Access is not plug and play. It requires a deep understanding of the network, users, and data flows. Proactive Data Systems starts by baselining inter-segment communication. We simulate breach scenarios. We translate business processes into access policies.
Then we configure ISE to assign SGTs, map group-based access control matrices, and integrate with existing identity stores. SD-Access is deployed in phases, starting with high-risk areas.
We’ve done this for BFSI firms in Colaba, healthcare providers in Bengaluru, and tech campuses in Chandigarh. The outcome is always consistent: lower exposure, faster detection, easier audits.
Build the Network You Can Trust
Your Zero Trust strategy won’t work if your network allows anything to move laterally. Authentication is the first step. Segmentation is the shield.
Cisco ISE and SD-Access give you the tools to embed security into the network itself.
Proactive gives you the architecture that turns that toolkit into action.
Proactive Editorial
