Automatically updating the link cost based on maximum speed of the interface
If the speed of the WAN interface of the SD-WAN on the CPE device is higher than the network speed provided by the service provider, you must limit the maximum speed of that interface to match the network speed.
Example: The service provider gives the client Internet access at a speed of 50 Mbps and the speed of the physical connection at the CPE device interface is 100 Mbps. In this case, for correct calculation of link cost and QoS, you must specify the maximum speed value of 50. |
The link cost value is calculated based on the maximum speed parameter. The relation of the maximum speed and cost parameters is as follows:
- Maximum rate specifies the maximum interface bandwidth for correctly calculating logical queues for QoS. Measured in Mbps (megabits per second).
- Cost determines the weight of the interface in the topology and is calculated using the formula:
Cost = 10,000,000 / Speed, whereSpeedis equal to the maximum speed value. The lower the cost value, the higher the priority of the link in the network topology.
When the maximum speed changes, the cost value changes for links in both directions. The lowest maximum speed value of the interfaces participating in the link is taken for the link.
You can manually specify the link cost as well as the maximum speed of the SD-WAN interface when creating it.
