Friday, September 14, 2007


Broadband bandwidth

It is interesting to observe the total load on Entanet's ADSL broadband connections via their on-line monitoring. This also shows the expected maximum rate for users on each of the BT Central connections feeding ADSL traffic into Entanet.

Entanet (via their resellers) offer a range of packages with fixed GB/month limits for example 30 GB/month peak / 300 GB/month off-peak. To get 300 GB/month would require the user to average 2 MBits/s through the off-peak period so in reality this is only available to a very small percentage of subscribers. "Off-peak" starts at 10pm and the surge in load is clear from the graph, usually taking until 2am to return to its pre-10pm level :-
There is clearly a lot of unused capacity in the 0200-0800 window and its a pity the downloaders that fire up at 10pm don't use scheduling software to exploit this slack period. As things stand Entanet use an "anti-loss tool" to throttle the individual connections down to 2 Mbits/s in order to avoid packet loss when the 10pm surge occurs.

Another interesting aspect is the fairly consistent upload (green) trace, running at about one third of the maximum downstream capacity. If this upstream traffic is capacity limited, as seems like with Asymmetrical DSL,a change to faster upstream speeds or to symmetrical technologies like FTTH would see a large increase in demand - possibly exceeding the download demand.


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