altq again

[Jukka Marin <jmarin%embedtronics.fi@localhost>]

Hi,

I'm wondering if "dropped packets" are normal when using bandwidth
limitation with pf/altq?  I have a 24/1 Mbps ADSL connection and wanted to
limit the upload bandwidth to 950 kbps.  When I did this, I started seeing
lots of dropped packets on the wan interface (vr0):

  vr0 in        vr0 out                    total in      total out     
 packets  errs  packets  errs colls drops   packets  errs  packets  errs colls 
drops
 8753027     0  7968994     0     0 327280  11372356     0 10608362     0  0 
327280

If I remove tha bw limit or make it very high (10 Mbps), I get no dropped
packets.

I have two VPN's running through the same interface.  I limited them to
250 kbps each (which seemed to work) and I have seen to dropped packets on
those interfaces.. only on vr0.

This is how I use altq:

altq on { $ext_if } priq bandwidth 10000Kb qlimit 1000 queue { ext_ps3, 
ext_pri, ext_std, ext_low, tcp_ack_out }
queue tcp_ack_out on { $ext_if } priority 6
queue ext_ps3 on { $ext_if } priority 5
queue ext_pri on $ext_if priority 4
queue ext_std on $ext_if priority 3 priq(default)
queue ext_low on $ext_if priority 1

...

pass out quick on $ext_if proto udp from { <openvpn_servers> } to any port 1194 
queue ext_pri keep state
pass out quick on $ext_if proto tcp from any to any port ssh queue (ext_low, 
ext_pri) keep state
pass out quick on $ext_if proto tcp from any port smtp to any queue ext_low 
keep state
pass out quick on $ext_if proto tcp from any to any port smtp queue ext_low 
keep state
pass out quick on $ext_if proto tcp from any to any queue (ext_std, 
tcp_ack_out) keep state
pass out on $ext_if queue ext_std keep state


Is dropping the packets the only way of limiting bw?  Why do the connections
actually work better without the limit (even though there's only 1 Mbps
available, limited or not)?

I also see ping whining about "no buffer space" when the limit is active.

  -jm