Hi All,
I have few questions on understanding of docsis.
1. As we know, CMTS uses Downstream to send packets to CM. How does the single instance of packet sends to multiple CM. At which place these packets get duplicated.
2. Also how does the specific packets (channel) are served to some CM. (eg paid channel, on demand TV), Since Downstream will send the packets to all CM.
Are you revering to multicast?
I am not sure if multicast is the one which helps to send the same packets (video channel) to each home (CM). I wanna know what make the signal sent from CMTS to reach each and every house ? At what point the single packet (mpeg) sent by CMTS gets duplicated, in order to reach all users .
"Video channel to each home" is sent by broadcast. CMTS also uses broadcast for Sync messages, UCD messages, MAP messages, etc.
When a cable modem locks to a QAM channel, it looks for the Sync, UCD and MAP messages from the CMTS. If it finds these it knows it is on an active DOCSIS channel. If they are not present, the cable modem assumes the DOCSIS channel is offline or it is on a video QAM channel and continues its search.
I hope this helps...