[lug] DD-WRT

Ken MacFerrin lists at macferrin.com
Wed Feb 22 17:07:30 MST 2006

Nate Duehr wrote:
> 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...

I've tried setting the QoS using MAC and IP settings and either will 
work fine for 1 call on 1 ATA with low traffic but having 3 lines on 2 
ATAs plus any real traffic (VPNs, SSH, SMTP/IMAP) and things start to 
get ugly.  I've also set the Vonage bandwidth down to 30Kb/s but I have 
not tried adjusting the MTUs.  Given that it's a cables modem line I'm 
not sure if this will be significant but it's worth a try..

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