Re: ALTQ and VoIP

[Bob DeBolt]

Greets

 I have learned some very valuable and time saving procedures to assist in the 
deployment of VOIP when using altq over the course of the last year that can 
possibly help you.

The greatest lesson to date is that you need to work with you ISP and have 
them give you readings for your line condition, twice a week for a month. 
Call other ISP sales departments as a prospective client and ask them to 
measure your line, you will likely discover some interesting things about why 
you are or are not getting the bandwidth you expect and why there are 
seeming inconsistencies in your altq. Often altq is not the problem.

What all this means is you probably aren't getting the bandwidth you are 
paying for.

Remember you are dealing with commodity Internet and as such all of it's 
inherent problems.

Bob

Re: ALTQ and VoIP

[Matt Pearce]

Ingolf Zeiner Petersen wrote:


Matt Pearce wrote:

I run 1536/256 ADSL here and found that a figure or 205Kb is the 
upper limit for me (versus the 170Kb you have) , any more and the 
queue wont drop packets correctly, any less and i'm not getting the 
full bandwidth i'm paying for.  If you have 256Kb try changing this 
figure and you might find you gain some extra speed.


Yeah, i know that i'm not getting the max out of my connection, but if 
i set it to anything over 200Kbit i get more lag/delay on the connection.




Thats odd, the only thing I can think of is a shoddy contention ratio or 
something is slightly misconfigured.  One way to check what is actually 
going on is to continually run pfctl -sq -v , this will show you how 
full your queue is and how many packets have been dropped.


I had a play a while ago with the qlimit but I had it added into the 
altq on rl1.. line, oddly it never changed a thing and never 
gave an error.  Since seeing your qlimit statements i've been playing 
with it for the past couple of days and working on tuning and found a 
qlimit of 1 serverly limited queues and they never saw full bandwith 
potential.  I found a good figure for me was 10 as opposed to a 
standard 50. My testing of the qlimit number had me pinging a local 
site while uploading with Azurues and watching its graph.


What where your ping-times?
Another thing: i'm trying to prioritize my outgoing icmp-packets.. and 
if I send 4 pings i get 8 packets in pfctl -vs rules on the rule i 
made. I would think that 4 packets would be more correct? *confused*


My ping times normally were 29-30ms but ranged from about 80-130ms while 
uploading flat out with Azureus although I found the true trial to be 
how well I could play games online.  It turns out that it was *slightly* 
more laggy but not to bad on a whole.  I'm not sure why you would be 
seeing 8 packets when you send 4 pings, I just did a test here and 4 
pings definately equals 4 packets.  Could this be related to you not 
being able to set your connection speed any higher ??


If you want email me your rules off list and i'll have a look and see if 
I can see any problems, sometimes a fresh set of eyes helps with simple 
errors.


Matt.