Integrating legacy server environments with modern network architectures often presents unique challenges, particularly when dealing with segmentation and isolation requirements. Private VLANs (PVLANs) have been a traditional solution for Layer 2 isolation in legacy networks. This article explores a straightforward approach to bridge a PVLAN-based legacy backup environment with a Cisco Application Centric Infrastructure (ACI) using Endpoint Groups (EPGs) and contracts, effectively replicating PVLAN functionality within the ACI fabric.
In legacy setups, PVLANs provide a method for Layer 2 segmentation. Typically, a PVLAN implementation includes isolated VLANs for client devices and a primary VLAN for servers. Clients in isolated VLANs can only communicate with servers in the primary VLAN, ensuring network isolation and security.
To integrate such a PVLAN environment with ACI, consider connecting the legacy infrastructure via a Layer 2 migration trunk. Within the ACI fabric, the PVLAN environment can be logically segmented into two EPGs: one for backup/DHCP servers and another for backup clients. The server EPG is associated with the primary VLAN ID of the legacy PVLAN, while the client EPG is associated with the isolated VLAN ID. Crucially, the client EPG should be configured in intra-EPG isolation mode to maintain client-to-client isolation, mirroring the behavior of isolated PVLANs.
To enable communication between clients and servers, a contract is defined between the client and server EPGs. An IP-Any contract effectively replicates the intended PVLAN functionality, allowing clients to communicate exclusively with servers. The Layer 2 migration trunk connecting the legacy environment to ACI should reside within the server EPG, utilizing the primary VLAN ID.
Initial testing of this configuration has proven successful. This approach, while not strictly network-centric in the purest sense, offers a pragmatic and relatively simple solution for integrating legacy PVLAN environments with ACI. Further migration of endpoints will be conducted to evaluate the solution’s robustness and scalability over time. This method provides a functional bridge, allowing for a phased migration strategy while maintaining necessary segmentation and isolation.
