What is the RSTP port cost for a 100 Mbps link?

To determine the RSTP (Rapid Spanning Tree Protocol) port cost for a 100 Mbps link, it's important to understand how port costs are calculated in this protocol. The cost of a port in RSTP is inversely related to the speed of the link—the higher the bandwidth, the lower the cost.

The cost for a port can be derived from a standard set of paths defined in STP (Spanning Tree Protocol) and RSTP, where the port cost values are predetermined. For Ethernet links, the cost of a 100 Mbps link is set at 200,000 according to the IEEE 802.1D and 802.1w standards. This value helps the network determine the shortest path to the root bridge when calculating the spanning tree.

Thus, for a 100 Mbps link, the designated port cost is correctly identified as 200,000, ensuring that the network can efficiently manage traffic and prevent loops.