Connecting multiple data centers at Layer 2 while minimizing the number of dark fiber connections required is a use case for deploying Ethernet Ring Protection Switching (ERPS). ERPS is a feature that provides loop prevention and fast convergence for Layer 2 networks that use ring topologies. ERPS can be used to connect multiple data centers at Layer 2 using fewer fiber connections than traditional mesh topologies1.

Virtual Switching Extension (VSX) is a high-availability technology that allows two ArubaOS-CX switches to operate as a single logical device. Split-recovery mode is a feature that prevents traffic loss when the Inter-Switch Link (ISL) goes out-of-sync and keepalive subsequently fails. When split-recovery mode is enabled, the secondary VSX member disables its downstream links until it synchronizes with the primary member. When split-recovery mode is disabled, the secondary VSX member keeps its downstream links up even when it is out-of-sync with the primary member1. Disabling split-recovery mode does not affect how the primary switch takes over again as the primary switch after a failure and reboot. The primary switch always takes over as the primary switch when it comes back online, regardless of the split-recovery mode setting. Therefore, this is not a use case for disabling split-recovery mode on ArubaOS-CX switches in a VSX fabric.

A Layer 3 VLAN interface is an interface that can be assigned an IP address and attached to a VRF. A VRF allows multiple instances of a routing table to co-exist within the same router. By attaching a Layer 3 VLAN interface to a VRF, you can isolate the traffic of that VLAN from other VLANs and routing domains12. This can enhance security and performance of the network.

A physical interface using Layer 2 mode cannot be attached to a VRF on an ArubaOS-CX switch. A VRF is a virtual routing and forwarding instance that provides logical separation of routing tables on a switch. A physical interface can only be attached to a VRF if it is using Layer 3 mode and has an IP address assigned to it1.

The exhibit shows a network topology where Switch-1 and Switch-2 are ArubaOS-CX switches that implement VXLAN without Ethernet VPN (EVPN). Switch-2 uses the same VNI-to-VLAN mappings as Switch-1. The question asks how the specified servers communicate, which means Server 1 and Server 4. Server 1 and Server 4 are in different VLANs and different VNIs, which means they are in different layer 2 segments. To communicate with each other, they require routing services between the VXLANs. However, using Virtual Routing and Forwarding (VRF) to tunnel iSCSI traffic through the network spine on the same links that data traffic uses is not the correct way to provide routing services. VRF is a technology that creates multiple isolated Layer 3 domains on a physical network, each with its own routing table. VRF does not provide any benefits for iSCSI traffic, as it does not guarantee bandwidth, priority, or quality of service. VRF also adds overhead and complexity to the network configuration1. To provide routing services between the VXLANs, the correct way is to use VXLAN routing with EVPN or distributed anycast gateway (DAG). VXLAN routing with EVPN allows the switches to exchange MAC and IP information using BGP EVPN control plane, and to perform routing between different VNIs using a centralized or distributed model2. DAG allows the switches to act as anycast gateways for their local hosts, and to route traffic between different VNIs using a symmetric or asymmetric model3. Therefore, this does not correctly describe how the specified servers communicate.