[asterisk-users] ADSL routers with integrated SIP QoS for other devices

[Andrew Kohlsmith]

On Saturday 28 April 2007 11:22 am, Chris Bagnall wrote:
> Thanks to all who replied to my thread a few days ago "SIP devices with
> packet loss tolerance". One of the suggestions that came out of that thread
> was to replace routers at users' premises with ones that support QoS.

Sangoma S518 (internal PCI) on a Linux box with iproute2/iptables/tc or BSD 
with pf.  These are the best solutions, IMO.

The latest Linux kernels also have SIP connection tracking/matching, so it 
should be possible to mark packets and prioritize based on iptables matching.  
I have not done this just yet, as the latest 2.6.20/2.6.21 kernels do not 
play nice with the wanrouter drivers.

(note: there was a recent patch to 2.6.20.4 which apparently has much better 
SIP matching, and has been tested successfully with Asterisk.  I have not 
tested it yet, and the iptables guys have rejected the patch as their 
direction for packet matching is shifting significantly in the near future.  
It can be found at 
http://thread.gmane.org/gmane.comp.security.firewalls.netfilter.devel/18860.)

I'm still looking for a miniPCI ADSL chipset that Linux can use, or an 
actual "raw" ADSL non-PCI chipset that I can design into an embedded system.  
If anyone has any leads, please don't hesitate to contact me!

If you're curious, I have my rc.tc script for Linux up on 
http://mixdown.ca/~andrew/rc.tc.  It's loosely based off of wondershaper, but 
works much better, IMO.  It does host-based prioritization for VOIP, puts 
mail just underneath bulk traffic, and P2P beyond that (if you have the p2p 
connmark stuff set).  I can completely saturate DSL links with the S518 with 
this config without appreciable VOIP degradation.

Even without an S518, this script works well with external ADSL/cable modems.  
You may have to play with the upload rate; some cheap ADSL modems will 
start "blocking" your upstream traffic beyond as little as 50% of the 
upstream rate.

-A.