Parameter for OSPF Cost Calculation

B

OSPF (Open Shortest Path First) is a routing protocol used in computer networks to determine the best path for data packets to travel from one network to another. OSPF cost is used to determine the best path through which the packets should be sent.

In Cisco routers, OSPF cost is calculated based on the bandwidth of the interface, which is the amount of data that can be transmitted per second. The lower the bandwidth, the higher the cost, and the less likely that path will be chosen.

The formula used to calculate OSPF cost is:

cost = reference bandwidth / interface bandwidth

The reference bandwidth is a fixed value, which is set to 100 Mbps by default in Cisco routers. However, it can be changed using the following command:

cCopy code
router ospf 1 auto-cost reference-bandwidth <value> 

The interface bandwidth is the actual bandwidth of the interface, which can be set manually using the following command:

csharpCopy code
interface <interface> bandwidth <value> 

In addition to bandwidth, OSPF cost can also be affected by the delay and MTU (Maximum Transmission Unit) of the interface. However, these parameters are not used by default in Cisco routers to calculate OSPF cost.

Therefore, the correct answer to the question is B. Bandwidth is the only parameter used to calculate OSPF cost in Cisco routers by default.