Chris Cappuccio wrote:
Just use the 'tos' tag in pf.conf to match against the IP tos field.
Most equipment sets this to something predictable, like 0x68 for RTP and
0xb8 for SIP.... Just use tcpdump to see what your RTP traffic is tagged
as, and also prioritize SIP above RTP. You could also try matching based
on IP addresses if they are predictable, or a combination of the two.
Using just the tos tag by itself may lead to applications cheating to get
priority bandwidth.
Yes, but not all setup are the same and it depend is the setup is based
on 802.1P or 802.1Q, meaning VLAN or Priority QoS on the phones, but
even then, not all phones are using the same priority. Example, Cisco
use CS3 for signaling and CS5 for RTP, Polycom use CS5 for both and in
all cases, it could be preset differently in some cases. It can also be
preset to be EF instead as well and that is also assuming the switch in
between the phones and the router, do not replace it. There is cases
that are replace, or preset as well. So, it can be done, but that depend
on the setup too. Again Cisco switch can be configure to trust the QoS
value receive on specific ports, or overwrite it regardless of what you get.
So, that is depending on the setup here.
Yes the best way is to make sure the phone itself does use the proper
QoS, specially if you also cascade your computer to the Ethernet port on
that phone should you use one of them, but then again it does depend on
the setup.
Or you can also use two different port on a switch that suppose
management as well and you preset the QoS of the phone higher then the
computer and make sure it's preset at the switch.
There is many ways to do this, so better then others, but all depend on
the setup and capability available there.
Unless you know what's use and what's possible with the hardware you
have and what you can and can't control, the safest way might just be to
filter on the source IP's that is assign to your phone assuming it's fix
all the time and add to that the UDP port range use for the RTP stream.
It should provide you the best setup and if you can be sure the QoS is
setup right on the phone and the switch accept as is and do not replace
it, then filtering on PF after that should definitely be easy to do.
Anyway, hope this provide you more to work with,
Best,
Daniel
