Background:

DOKOM Gesellschaft für Telekommunikation mbH (DOKOM21) is a subsidiary of Dortmunder Stadtwerke AG (DSW21) and manages telecommunications and data networks with approximately 6,600 end devices. Due to growing security requirements—particularly those mandated by the Energy Industry Act (§11 EnWG)—the previous NAC solution was replaced by ARP-GUARD.

Challenge:

• Ensuring IT security in office and control networks
• Requirements for a multi-tenant system with granular access control
• Flexible VLAN control for the individual allocation of network resources
• Need for 802.1X authentication, two-factor Wi-Fi access, and IP range management
• Compliant implementation of legal and technical security guidelines
   

Solution:

After extensive testing, DOKOM21 chose the ARP-GUARD NAC solution from ISL, implemented by premium partner GORDION Data Systems Technology GmbH:

• Comprehensive device detection and access control
• Multi-tenant capability to support different business units
• Fine-grained policy framework down to the sensor and user level
• VLAN switching with customizable configuration
• Integration of existing authentication mechanisms, including certificate verification
• Support for compliance requirements and sophisticated reporting functions

Result:

• Fast and seamless implementation in less than two months
• High transparency and control over all end devices on the network
• Significant reduction in service ports through dynamic VLAN assignment
• Efficient training of IT staff through GORDION
• Foundation laid for the next phase: technical networks

Conclusion:

With ARP-GUARD, DOKOM21 now has a powerful, flexible, and compliant security solution that meets the complex requirements of both the energy sector and modern office communications. The project demonstrates how a customized NAC approach can be successfully and efficiently implemented in a small-to-medium-sized business.