A network engineer is troubleshooting a connectivity issue between two virtual machines (VMs) that are configured in different subnets but reside on the same hypervisor. The VMs are connected to a standard virtual switch. They can ping other VMs in their respective subnets but cannot ping each other. Which configuration element is most likely missing or incorrect?
- AInsufficient physical NIC bandwidth on the hypervisor
- BVLAN tagging on the virtual switch ports
- CA virtual router or Layer 3 gateway configured on the hypervisor or connected to the virtual switch
- DPrivate VLAN (PVLAN) configuration preventing inter-VM communication
Show answer & explanationAnswer & explanation
Correct answer: C. A virtual router or Layer 3 gateway configured on the hypervisor or connected to the virtual switch
VMs in different subnets require a Layer 3 device (router or gateway) to forward traffic between them. If they are on the same hypervisor and connected to a standard virtual switch, the virtual switch itself only provides Layer 2 connectivity. Without a virtual router or a physical router connected as their gateway, they cannot communicate across subnets.
Why the other options are wrong
- A. Insufficient bandwidth would cause performance issues, not a complete lack of connectivity between different subnets.
- B. VLAN tagging is for Layer 2 segmentation; while necessary, it doesn't provide Layer 3 routing between different subnets.
- D. PVLANs prevent communication within the same VLAN or subnet; if VMs are in different subnets, PVLANs are unlikely to be the primary issue preventing routing.
Virtual Routing
Virtual routing refers to the capability of virtualized environments to provide Layer 3 forwarding services, typically through a virtual router appliance or a routing function integrated into a distributed virtual switch. This enables communication between virtual machines residing in different IP subnets.
- Enables Layer 3 communication between VMs in different subnets.
- Can be a dedicated virtual appliance or a DVS feature.
- Essential for inter-subnet connectivity in virtualized environments.
Memory trick: Different Subnets, Need a Router's Blueprint.