In the RFCs, OSPF selects a path based on a single value called "cost", which is not defined to be a particular parameter or data.
It is implementation dependent, so how IOS OSPF derives its cost may or may not be different from some other vendor's OSPF implementation.
The cisco IOS OSPF uses a value based on the bandwidth of the interface. This value is inversely proportional, so a higher bandwidth has a lower cost. The "ospf auto-cost reference-bandwidth [value]", where the value is in megabits per second, changes the calculation. The default for this setting is 100, so a 100mbit interface has a cost of 1, a T-1 has a cost of 64, etc.
In the routing table, the lower OSPF cost value is preferred. If you have two paths of the same cost, they will both show up in the results of "show ip route".
You should be careful to set your 'bandwidth' statements on your serial interfaces to ensure the calculation works as intended. Otherwise, all serial interfaces are treated as 1.544mbit in the OSPF cost calculation.
We have 3 identical switches configured by someone else and would like to claim some of the Gigabit ports(G1/G2/G3/G4) for use on servers. When we try to change the wiring and configuration, we run in to connectivity issues. Attached is a des...
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...