In Huawei's CloudFabric Solution, iMaster NCE-Fabric automates overlay network (e.g., VXLAN) configuration, while the underlay network is manually deployed. Tenant hosts failing to access external networks indicate a connectivity issue, likely at the overlay-underlay boundary or security layer. Let's evaluate each option as a possible cause:
A . No return route is configured on the PE: This is a possible cause. The Provider Edge (PE) device (e.g., border leaf or router) must have a return route to the tenant's VXLAN network for external access. Without it, traffic from external networks cannot reach the DC. POSSIBLE CAUSE.
B . The engineer did not check whether the service loopback interface needs to be configured on the VXLAN network based on the switch model: This is a possible cause. Some Huawei switch models (e.g., CE series) require a service loopback interface as the VTEP source IP. If omitted or misconfigured based on the model, external connectivity fails. POSSIBLE CAUSE.
C . No firewall security policy is configured when host traffic passes through the firewall: This is a possible cause. If a firewall is in the path (e.g., between tenant VPC and external network), a missing security policy (e.g., allowing outbound traffic) blocks access. POSSIBLE CAUSE.
D . The MAC address of the NVE interface on the VXLAN network is not manually specified: This is not a possible cause. The Network Virtualization Edge (NVE) interface in VXLAN does not require a manually specified MAC address; it uses the switch's system MAC or auto-generates one. iMaster NCE-Fabric typically handles this automatically, and manual specification is neither required nor a common fault point for external access issues. NOT A POSSIBLE CAUSE.
Thus, D is not a possible cause of the fault.