On 7 Jun 2012, at 19:53, "Justin Finkelstein" <[email protected]<mailto:[email protected]>> wrote:
On 7 June 2012 19:49, Neil J. McRae <[email protected]<mailto:[email protected]>> wrote: in some cases yes - ATM based DSL lines are particularly bad at coping with VoIP under congestion - I presented some stats from my days at COLT on this at UKNOF4 I think. This implies the same may be true for consumer end users - am I right in this interpretation? if the consumer line uses ATM yes. its an issue with cells and AAL. IP based DSL lines perform massively better. However even with QoS and other priority chaos there is still no guarantee even on IP friendly access links. So QoS doesn't help in this scenario? QoS only promises to drop something or do nothing (buffer)- there is no intelligence to ensure that's enough to absolutely guarantee VoIP will be ok. TDM works because it promises an end to end path at a specific rate. Sent from my iPad On 7 Jun 2012, at 16:10, "Christian de Larrinaga" <[email protected]<mailto:[email protected]>> wrote: Neil Do you find the model of asynchronous links to premises makes it tougher for everything to get "enough bandwidth" ? Christian On 7 Jun 2012, at 15:05, Neil J. McRae wrote: IP networks 101. If you have enough bandwidth everything gets a good deal. Sent from my iPhone On 7 Jun 2012, at 10:42, "Justin Finkelstein" <[email protected]<mailto:[email protected]>> wrote: nteresting; so it sounds, from what you say, that by default VoIP gets a "good deal" out of the available bandwidth? On 7 June 2012 09:55, Adrian Kennard <[email protected]<mailto:[email protected]>> wrote: On 07/06/12 09:45, Justin Finkelstein wrote: > > This may be the wrong forum for this message, but I was wondering about > how VoIP is handled as part of people's various traffic shaping policies > - i.e. is this something people take account of? Our LNSs know the rate of every line, and shape to match the line rate but with small packets having more priority over large - this works well for VoIP, but also ACK packets, DNS, interactive (key strokes), etc. We find people can fill their line with torrents and still have perfect VoIP calls. > Also: if one of the UK's ISP's decided to implement QoS on their > customer base's users and then prioritise VoIP, what kind of impact > would this have on the upstream network? Upstream is not usually an issue as it is not usually congested!
