dkwok@iware.com.au
2004-Jan-15 15:34 UTC
[Asterisk-Users] re: hardware requirement -asterisk
Referring to my previous post about degradation of voice quality when
having more than 2 connection.
The actual route is:
pc xlite -> local asterisk box -> iaxtel -> local asterisk
I have tried out a different situation:
pc xlite -> local asterisk box -> iaxtel
and the second connection
pc xlite -> local asterisk box -> iaxtel -> local asterisk
The same degradation happens as soon as the second connection is connected.
I am suspecting the ADSL connection. The internet part is ADSL with 512k
down and 128k UP. The nic is a 3c905c 100baseTX and connected to a NEC
ADSL modem.
# ifconfig xl0
xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
^^^^^^^^
address: 00:01:02:78:11:e8
media: Ethernet autoselect (10baseT)
status: active
inet 203.219.167.126 netmask 0xfffffffc broadcast 203.219.167.127
inet6 fe80::201:2ff:fe78:11e8%xl0 prefixlen 64 scopeid 0x2
But ifconfig seems to suggest that it is running in simplex mode.
Is the degradation a result of the ADSL connection?
David Kwok
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> # ifconfig xl0 > > xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > ^^^^^^^^ > address: 00:01:02:78:11:e8 > media: Ethernet autoselect (10baseT) > status: active > inet 203.219.167.126 netmask 0xfffffffc broadcast 203.219.167.127 > inet6 fe80::201:2ff:fe78:11e8%xl0 prefixlen 64 scopeid 0x2 > > But ifconfig seems to suggest that it is running in simplex mode.If the DSL modem is running in full duplex mode and the card in your machine has auto-negotiated to half-duplex, things go to hell quickly. Auto-negotiation sucks anyway. It works about as well as Plug & Play. ifconfig xl0 media 10BaseT mediaopt full-duplex Or hell, try ifconfig xl0 media 100BaseTX mediaopt full-duplex Run "netstat -I xl0 -i 1" and watch for collisions.
--- "dkwok@iware.com.au" <dkwok@iware.com.au> wrote:> Referring to my previous post about degradation of voice quality when > > having more than 2 connection. > > The actual route is: > > pc xlite -> local asterisk box -> iaxtel -> local asterisk > > I have tried out a different situation: > > pc xlite -> local asterisk box -> iaxtel > > and the second connection > pc xlite -> local asterisk box -> iaxtel -> local asterisk > > The same degradation happens as soon as the second connection is > connected. > > I am suspecting the ADSL connection. The internet part is ADSL with > 512k > down and 128k UP. The nic is a 3c905c 100baseTX and connected to a > NEC > ADSL modem. > > # ifconfig xl0 > > xl0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 > ^^^^^^^^ > address: 00:01:02:78:11:e8 > media: Ethernet autoselect (10baseT) > status: active > inet 203.219.167.126 netmask 0xfffffffc broadcast > 203.219.167.127 > inet6 fe80::201:2ff:fe78:11e8%xl0 prefixlen 64 scopeid 0x2 > > But ifconfig seems to suggest that it is running in simplex mode. > > Is the degradation a result of the ADSL connection?The fact that you 10BaseT is simplex will not matter as 10Mbps is 20X faster than even the ADSL's downlink speed of 512kbps You bottle neck is the 128kbps uplink speed. You'd think that is a lot but you can't got say "codec X uses Y bits per seciond, so two calls are 2Y bps and keep adding calls untill your 128bps is "full". It don't work that way. Think in terms of _probibilities_. Say your uplink is one quarter full. What does that mean? It means it is running at 128kbps 25% of the time and zero 75% of the time. So if an audio packet is placed on that line there is a 25% chance it will be delayed in an outbound queue. It is those delays that you hear. Actually the amount of delay is a distribution and what you hear are the "tails" of the curve. (i.e. there is a 25% change of a delay then there is a 12% change that two packets back to back will be delayed, 6% of three and so on.) With one audio stream there is no competition for the uplink. Adjusting the packet size can have an effect. Very long packets are not good ====Chris Albertson Home: 310-376-1029 chrisalbertson90278@yahoo.com Cell: 310-990-7550 Office: 310-336-5189 Christopher.J.Albertson@aero.org KG6OMK __________________________________ Do you Yahoo!? Yahoo! Hotjobs: Enter the "Signing Bonus" Sweepstakes http://hotjobs.sweepstakes.yahoo.com/signingbonus