RE: [nznog] telecom planning to break VoIP over its network?
All, I believe the only "things" that Telecom have done to-date are: 1. To change the ADSL modulation speed to each subscribers "plan speed" + ATM overhead. For example, the 256/128 kbps plan has an ADSL modulation speed of 320/160 kbps (downstream/upstream). 2. Always have ADSL interleaving on, with a relatively long interleaving delay. Interleaving is used between the ADSL modem and the DSLAM to improve error correction performance against burst errors. The above means: *** An interleaving delay of approximately 28 ms is introduced *** A serialisation delay of approximately 3-50 ms is introduced (64 - 1024 byte packets). In other words, the total one-way latency is approximately 36 - 83 ms depending on packet size. Jitter will of course increase as latency increses. (Packets arriving behind large packets etc.) Which is bad for VoIP. The question is: did Telecom do this to make VoIPoUBS harder to implement? (The latency and jitter could be significantly reduced by lowering the interleaving delay and by not limiting ADSL modulation rates. Interleaving is not needed if the subscribers local loop is of a reasonable quality.) --Olof
participants (1)
-
Olof Olsson