A NetScaler configured with MBF, USIP, USNIP, and Layer 3 mode is deployed. After adding a new router and attempting to route traffic, packets still do not reach the new router. Which mode should be disabled to enable routing via the new router?

A NetScaler configured with MBF, USIP, USNIP, and Layer 3 mode is deployed. After adding a new router and attempting to route traffic, packets still do not reach the new router. Which mode should be disabled to enable routing via the new router?

• A. Layer 3 mode
• B. USIP
• C. MAC-based Forwarding
• D. USNIP

Answer: (C)

MAC-based Forwarding makes the appliance forward packets primarily by MAC address, effectively treating traffic as a bridge at Layer 2 rather than using IP routing to determine the next hop. When a new router is added, you want the device to make routing decisions based on IP, consulting its routing table to send packets toward the new gateway. If MAC-based Forwarding is still enabled, the path determined by the MAC (the existing gateway) is taken, so traffic may never reach the newly added router. Turning off MAC-based Forwarding lets Layer 3 routing take over, so the device will route packets to the next hop specified in its routing table—the new router—allowing proper traversal of the network. The other features (USIP, USNIP) relate to IP address handling, but MBF specifically overrides routing by doing L2 forwarding, so disabling it is the correct change to enable routing via the new router.

MAC-based Forwarding makes the appliance forward packets primarily by MAC address, effectively treating traffic as a bridge at Layer 2 rather than using IP routing to determine the next hop. When a new router is added, you want the device to make routing decisions based on IP, consulting its routing table to send packets toward the new gateway. If MAC-based Forwarding is still enabled, the path determined by the MAC (the existing gateway) is taken, so traffic may never reach the newly added router.

Turning off MAC-based Forwarding lets Layer 3 routing take over, so the device will route packets to the next hop specified in its routing table—the new router—allowing proper traversal of the network. The other features (USIP, USNIP) relate to IP address handling, but MBF specifically overrides routing by doing L2 forwarding, so disabling it is the correct change to enable routing via the new router.