KEIN Problem, nur neugirig ... DOCSIS Modem

[Atlan]

Ich hab diesen Bericht über DOCSIS Modem gefunden http://cable-dsl.home.att.net/#Asymmetry ... ich verstehe aber diesen Teil nicht ... kennst sich damit jemand aus ?

Auszug:
The aggregate upstream capacity of 4 channels would be about 2.5 Mbps, as compared to downstream capacity of 27 Mbps. If the upstream saturates, the downstream rate will drop to about the same speed, a dramatic slowdown of about 90% (2.5 Mbps as compared to 27 Mbps).

Even with cable modems capped to 128 Kbps upstream, 2.5 Mbps upstream capacity can handle only 20 (2.5 Mbps / 128 Kbps) simultaneously active modems before saturation. That's generally not a problem if cable modem usage is typically (1) infrequent, (2) downstream [e.g., web surfing], and (3) interactive [e.g., fetch-use]. The system can break down if those conditions are not met.

This makes it easier to see why certain Cable Internet providers condemn continuous use of upstream (e.g., running a popular public service) as "abuse" -- each such subscriber consumes capacity normally allocated for 1000 / 20 = 50 subscribers. Worse, there's a threshold effect: If the upstream is running at (say) 80% of capacity with typical subscribers, it takes only 4 (out of 1000) heavy upstream users at 128 Kbps to drive the upstream into saturation, thereby slowing downstream to a crawl for all subscribers on that segment. (Exact numbers, of course, depend on actual channel numbers and speeds.)

[_m3]

Und was verstehst du nicht?

[Atlan]

Warum bricht die Leistung zusammen ?

If the upstream saturates, the downstream rate will drop to about the same speed, a dramatic slowdown of about 90%