[lug] DD-WRT

Nate Duehr nate at natetech.com
Wed Feb 22 14:47:21 MST 2006

Daniel Webb wrote:
> On Fri, Feb 10, 2006 at 11:36:15AM -0700, Ken MacFerrin wrote:
>> This is what I'm really interested in.  I have 2 ATA's with 3 Vonage 
>> lines running behind one of my WRT54G's on a Comcast HSI connection. 
>> I've tried many different combos of QoS settings but have yet to find 
>> one that works well under any real load.  Most any time there is heavy 
>> traffic (especially upstream) the voice quality takes a nosedive.  I'd 
>> love to find a firmware that could get VoIP QoS right.  Most the 
>> firmwares will allow you prioritize SIP but it's not much help as SIP is 
>> only used to setup the VoIP connection.  The actual voice protocol is 
>> usually RTP or some other protocol that that's similarly hard to track.. 
> Can't you just classify by source/destination IP address if you're using
> external ATAs?  If you feel masochistic, do the tc/iptables stuff yourself.
> I've got a start on my web site, but it needs improvement/customization to be
> really useful.  It works ok for me though.

Follow-up on this.  I now have a Linksys PAP2 hooked up to one of the 
internal ports on the WRT54GS running the DD-WRT software, and I've used 
the internal QoS settings to set that port to the highest priority and 
lower everything else a notch.  Since I also use it from time to time, I 
used the built-in settings for Skype/SkypeOut in the DD-WRT software to 
prioritize that as well.

I also lowered the voice quality of the Vonage that's feeding the PAP2 
to 30Kb/s just 'cause... who needs to waste 90Kb/s for a phone call?  :-)

So far, virtually zero complaints.  When originally installed the Vonage 
  was NOT on a port of the WRT54GS, was not QoS'ed and was set at 90K. 
I got reports that I was breaking up on every call.

Another important thing I found... MTU sizes were ALL too big for the 
DSL line.  PPPoA sucks away some bits, of course, and I'd never 
accounted or changed anything for it.  Also the WRT54GS with QoS on 
sucks away even a few more... so MTU's had to be adjusted behind it to 
account for the correct sizes for what would actually pass without 
fragmenting.  I do NOT see a setting in the PAP2 for this, 
unfortunately, or it would probably help... but at least now the only 
device that's probably still set to 1500 MTU is the PAP2, giving the 
poor little Linksys less to do unfragmenting things... if it's not just 
passing them along...


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