Question on terminology

Feb 17, 2009 2 Replies

Sorry if this isn't cisco specific, but I figure folks here would know.


In ISP terms, what terminology would be used to discuss how much bandwidth is actually provided to each user relative to the advertised modem speed ?



For instance, if you have 100 users at 7mbps on a DSLAM, but the dslam has only 100mbps link to the backbone, if all users downloaded at the same time, they'd only get 1mbps each, or 1/7 of their advertised speeds.



Is this called over subscription rate ? (iof not, how is it called ?)



In terms of cable, is it correct to state that the frequency allocation of the coax defines available bandwidth for the group of users attached to that coax segment ?



If you allocate 30mhz to data on the coax, does this imply roughly



30mbps capacity, or is the ratio of mhz per mbps very different ?


If ISPs calculate that on average, their customers draw 300kbps (intermittent bursts of HTML text followed by long idle periods while user reads the page), how is this rate called ?


Anyone know if there are publically available tables showing relationship between average use rate (or whatever it is called), advertised speeds and time.



(aka: something showing how average use is affected by increased speeds, and how changing patterns change average use (downloading movies instead of text only HTML for instance) ?



Or would such information be considered highly proprietary ?


Contention is one term in common use.

I would think it's a long way from being 1:1.

I'd call it 'bursty' traffic.

I reckon such information would be considered almost useless. It used to be that most usage was bursty, with a small minority hammering the P2P, but nowadays the 'average' data usage has massively increased with the advent of applications like Youtube, iPlayer, Windows Update etc. This has led to more ISPs employing bandwidth caps.

yeah this is major over subscription

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