In one embodiment, a device includes: a transceiver operable to transmit packets to and receive packets from a modem; and a logic engine configured to transmit first packets at a rate through an upstream path for a modem to an Internet node such that no throttling is triggered in the modem, the logic engine being further configured to transmit second packets through the upstream path for the modem to the Internet node at a rate sufficient to trigger throttling in the modem if the modem implements throttling, the logic engine being further configured to compare an average transmission time for first packets to an average transmission time for the second packets to determine whether the modem implements throttling.