フリー問題

問題文

Traffic between two hosts in an overlay is spread over several physical paths. Which layer made that decision?

選択肢

1. Neither, because an overlay always uses a single path, so adding a second link between two racks leaves every flow exactly where it already was.
2. The workload, by setting a field in the inner header, which requires the devices in the middle to look past the encapsulation they are forwarding.
3. The underlay, using the fields of the outer header, because the overlay only sees a single logical hop between the two endpoints.
4. The overlay, since it is the layer that chose which endpoint to send the traffic to and therefore also chose which of the available physical paths toward that endpoint each individual packet was going to be carried over on the way there.