Hi Craig, > I would like to prioritise all VoIP traffic on a linux router. I am new > to QoS, tc and TOS, to please be gentle. > > My logic works like this: > > 1) identify the VoIP packets > 2) mark packets using iptables (with TOS?) > 3) use tc to prioritise the marked packets. > > Is this logic correct? If not, where is it flawed? it can work, VoIP for me is H323, for SIP i haven't checked yet what their ports are.. > I understand that VoIP used the udp protocol and has packet sized less > than 250 bytes. Is simply reducing the MTU on the interfaces good enough > to give better thoughput, without the lag of larger packets trying to > pass though? Well, reducing MTU is most probably not a good idea, as you force more packets benig sent even when you can keep the overhead to just 1 packet with large payload. so i wouldn't do that.. VoIP (speaking of H323) is UDP traffic on random ports but can be limited by using either GnomeMeeting or nmproxy (http://www.cryogenic.net/nmproxy.html), thouch i haven't tried the latter so far.. As of GnomeMeeting you can simply use a match for UDP ports 5000-5003 (on a direct connection)... For OhPhone and OpenMCU etc. the ports may vary.. If you don't use H245 tunneling there's also some TCP ports involved (for GM 30000-30010). Using a GateKeeper will also have another port-range.. but checking either source, mailinglist or support info of these products will shed some light where you'll be most lucky matching their packets.. > Are there any good HOWTOS? None that i know of, sorry.. Good luck! ;) -- Best regards, Kilian
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