When you first turn on your modem, it goes through a power-on self test. On completion of this test (after about a minute), the Downstream light will start to blink green. Once the modem syncs on a downstream channel, the Downstream light will go solid green and the Upstream light will start blinking green. The Upstream light will go solid green once it has established a connection. Depending on your service, additional channels may bond together. During the bonding process, the Upstream and Downstream lights will blink blue. When the channels successfully bond, the Upstream and Downstream lights will go solid blue. This sequence will recur each time you power on your cable modem.