Quote:
Originally Posted by HarryT
No, with the very greatest respect that's not the case. ADSL certainly is a contended resource at the level of the local telephone exchange, and performance varies with the activity of local users.
Eg, my nominally 8MBit ADSL service has a download speed of about 5MBit/sec at quiet periods such as this (early Sunday morning). During working hours, when all the local businesses come online, download speed drops to about 1.5-2MBit/sec because of contention at my local telephone exchange. Between 4-6pm, speed gradually increases again as those businesses stop using the internet.
Cable is contended at the local street cable level; ADSL is contended at the telephone exchange. To say that it's a fixed bandwidth resource is highly misleading. The only fixed bandwidth part of the system is the wire from your house to the telephone exchange; beyond that, it's all shared.
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Then your ISP has oversold their capacity and/or improperly configured their network. This is quite often intentional in order to add fees. But to claim xDSL is shared is flat out incorrect. As I point out at some point ALL networks must share or they can't communicate with other networks. It is proper design of the load balancing and over all topology that affects this. I have no idea what they are doing in the UK or for your service but I have never encountered a case where an xDSL service degraded based on use. Now if there is insufficient capacity out to the external network, say the web, then sure there might be some sort of degradation but that has nothing to do with the xDSL part of the service.
End user slow downs are 99% of the time related to changes an ISP makes in the layer(s) above the DSLAM and can always be corrected by the ISP returning the end user's service to what they are paying for. Otherwise it can often be the case where the xDSL line to the end user is actually moved to a cable bundle which also has fiber near by. The fiber will often be improperly shielded and generate a lot of xtalk interference which pretty much makes the service slow down to try and correct the errors. I don't care what the ISP is saying though xDSL not shared in the sense it is used in network design.
Sure things can go awry in the CO at any level but again that is not part of the xDSL definition. Your ISP may vary.
You can spin it however you want but you are not right it's that simple. And I am done.