VOIP Prioritization

[ytodros]

I was wondering if it would make sense to add rules (to iptables?) to give priority to VOIP traffic?
Being that the distro ships with a full preset set of rules, why not just include QoS so it does not have to compete with the webserver or anything else.

 

[jroper]

Hi

Good idea, do you have a handy set of rules to hand that will do what you describe?

Joe

 

[ytodros]

Well I looked around for a qos solution, and found this http://www.voip-info.org/wiki/view/Linux+Router (an incomplete tutorial), but looking a bit further, QoS seems to not be not such a simple thing.
I saw posts about MTU size, jitter (http://zeroshell.net/eng/forum/viewtopic.php?t=574) among other things (QoS Protocol, Kernel, , etc. etc.) And it ultimately seems to take a little more then marking a few packets upon iptables inspection (even if marking is done, which process will actually look at the tagging and give it 'push it through').
At this point, I am way over my head, and being that I haven't a clue as to which capabilities are built in to the kernel/distro already, any rules I did put together is worthless.

 

[MrBostn]

I was wondering if it would make sense to add rules (to iptables?) to give priority to VOIP traffic?
Being that the distro ships with a full preset set of rules, why not just include QoS so it does not have to compete with the webserver or anything else.

I'd go with a PFsense router. They do QoS nicely.

Unless it's some sort of private network or MPLS, QoS can't do much QoS'ing, over the internet. How do you QoS the 17 other hops to/from your network?

 

[ytodros]

Ultimately (at least in my setup) it would be best to have a seperate router doing QoS, but there always is other traffic on the machine itself, where VOIP should always be a priority for the computer.
In my case it does happen to be a 'private network' - it is a dedicated (T1 class) line, which I am temporarily plugging directly in to the PBX, and I notice that if I go to the command line and start downloading something, 0 priority is given to the VOIP traffic.

 

[RizSher]

With Mega or Giga bit ports on most servers and routers, internal QoS is generallly not an issue. General advice on these and other forums has always been to have dedicated machines for *, what other network traffic would these generate that could potentially hog an ethernet connection?.

Router based QoS, for instance, Tomato firmware, works quite well for differentiating between bulk traffic like torrents, video etc and VoIP, but thats really for maing the best use of the internet, not intranet bandwidth.

Riz

 

[ytodros]

Even on a machine dedicated to asterisk, there are update checks, web requests to the server (freepbx, PIAF, etc. Even if the requests are sparse), Email notifications, and I'm sure others.
And again, this would obviously be most relevant where the computer is being used as the WAN gateway (even if the connection is only for itself).

 

[dswartz]

check out astshape

This is an iptables based script that works fine on RHEL based systems (I've used it on one). You can tweak it pretty much any way you want to prioritize outbound VoIP.

 

[jmullinix]

I use PFSense and set a priority on all outbound traffic from the phone server. Inbound is a bit of a hack. Set your rate about 10% less than your rated inbound speed on the PFSense box. This way, when the pipe gets full, PFSense will start sending congestion packets to the source host telling it to slow down. This slows the TCP traffic, but doesn't affect the UDP traffic so voila, inbound QOS, sort of.