 espaethDigital PlumberPremium,MVM
join:2001-04-21
Minneapolis, MN
kudos:2
 ·Clear Wireless
| reply to dadkins
Re: Upload congestion? said by dadkins:Hmmm... Comcast CRAN - redundant 10G to the headend. Pretty sure that is a symmetrical 10G... both of them. So, I can have 16+mbps down and 2mbps up - where is the rest of all the upload getting chewed up at? It's getting chewed up by RF interference and the need to control upstream broadcast transmit intervals.
On the downstream it's one transmitter, multi-receiver. The CMTS transmits downstream constantly with no need to pause, the cable modems grab whatever frames are theirs off the wire and life is happy. The CMTS can only listen to one modem at a time, however, so that's where mechanisms like TDMA divide out bandwidth timeslots that each modem can request to transmit up. Multi-speaker / single-listener is a more complicated problem to solve, and one of the principle reasons that upstream capacity is limited. |
