Is QoS well implemented in IPv4? Per-Tore / LA7NO
On 18 July 2014 11:22, David Woolley <[email protected]> wrote: > It is standard to use UDP (RTP) over VoIP for the reasons given by Iain. > Over a corporate network, VoIP traffic should have a QoS tagging on the IP > packets which causes routers to prioritise it. VoIP over the internet has > always been done for cost, not quality reasons, as the whole concept behind > IP networks is at conflict with constant rate traffic; the telephone > industry devised ATM as a packet network for that application (although they > are now moving to IP, because voice is no longer the dominant bandwidth user > - but I am sure they will prioritise their voice traffic). > > RTP has a marker bit which indicates a safe place to dump a latency buffer's > contents. Conceivably setting this during tuning would be a good idea. If > the remote operation protocol doesn't user RTP, someone has been > re-inventing the wheel. > > As someone mentioned WiFi. It is generally accepted, in the VoIP world, > that WiFi and VoIP don't mix because WiFi introduces additional latency. I > believe it also does link level retransmission which, means latency can be > particularly bad if you don't have ideal conditions. > > -- > David Woolley > Owner K2 06123 > > [ Top quoted through list policy, not preference. ] > > On 16/07/14 20:35, iain macdonnell - N6ML wrote: > >> The flip-side is that use of a "reliable" protocol, such as TCP, which >> detects and retransmits dropped packets, causes increasing latency >> over time (the more packets get retransmitted, the further behind >> "real time" you get). For something like a "real time" audio stream, >> it generally better to just accept the packet-loss. The problem of >> increasing latency can affect UDP too - some types of unreliable links >> cause a sequence of packets to get queued, then all transmitted in a >> burst. > > >> It's a tricky problem area. My personal software >> solution uses UDP and a moderately-sized buffer, and when the buffer >> builds up to a point where the latency is more than I like, I click a >> button to dump the contents of the buffer, and return me to >> low-latency. > > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
