What is the reason BPDU guard is not activated on all access ports after enabling it globally?

What is the reason BPDU guard is not activated on all access ports after enabling it globally?

• A. PortFast is not configured on all access ports
• B. BPDU guard must be configured on each port individually
• C. The access ports are part of a trunk
• D. Only switch uplinks can use BPDU guard

Answer: (A)

The reason BPDU guard is not activated on all access ports after enabling it globally is that PortFast must be configured on those access ports. BPDU guard is specifically designed to protect the network from unintended bridge protocol data units (BPDUs) that could cause a topology change or a loop, typically when devices such as end hosts are connected. However, BPDU guard only takes effect on ports where PortFast is enabled. This configuration tells the switch to treat the port as a connection to an end device instead of another switch or bridge, which is significant since BPDUs should not be expected on such ports. If PortFast is not configured on an access port, BPDU guard will not activate since the port is still operating in its default spanning tree mode, leading to the potential for legitimate BPDUs being processed on that port without triggering a guard. Hence, for BPDU guard to provide the intended protection on access ports, PortFast must first be enabled on each individual port that is expected to connect to end devices.

The reason BPDU guard is not activated on all access ports after enabling it globally is that PortFast must be configured on those access ports. BPDU guard is specifically designed to protect the network from unintended bridge protocol data units (BPDUs) that could cause a topology change or a loop, typically when devices such as end hosts are connected.

However, BPDU guard only takes effect on ports where PortFast is enabled. This configuration tells the switch to treat the port as a connection to an end device instead of another switch or bridge, which is significant since BPDUs should not be expected on such ports. If PortFast is not configured on an access port, BPDU guard will not activate since the port is still operating in its default spanning tree mode, leading to the potential for legitimate BPDUs being processed on that port without triggering a guard.

Hence, for BPDU guard to provide the intended protection on access ports, PortFast must first be enabled on each individual port that is expected to connect to end devices.