improve IP TOS support for SIP and IAX2 (issue #6355, code from jcollie plus modifications)

git-svn-id: http://svn.digium.com/svn/asterisk/trunk@15435 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 63 insertions, 0 deletions

diff --git a/doc/ip-tos.txt b/doc/ip-tos.txt
new file mode 100644
index 000000000..bac457e33
--- /dev/null
+++ b/doc/ip-tos.txt
@@ -0,0 +1,63 @@
+IP Type of Service settings for VoIP channels
+---------------------------------------------
+
+Asterisk can set the Type of Service (TOS) byte on outgoing IP packets
+for various protocols.  The TOS byte is used by the network to provide
+some level of Quality of Service (QoS) even if the network is
+congested with other traffic.  For more information on Quality of
+Service for VoIP networks see the "Enterprise QoS Solution Reference
+Network Design Guide" version 3.3 from Cisco at:
+
+<http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a008049b062.pdf>
+
+In sip.conf, there are three parameters that control the TOS settings:
+tos_sip, tos_audio, and tos_video.  tos_sip controls what TOS SIP call
+signalling packets are set to.  tos_audio controls what TOS RTP audio
+packets are set to.  tos_video controls what TOS RTP video packets are
+set to.  There is a "tos" parameter that is supported for backwards
+compatibility.  The tos parameter should be avoided in sip.conf
+because it sets all three tos settings in sip.conf to the same value.
+
+In iax.conf, there is a tos parameter that sets the global default TOS
+for IAX packets generated by chan_iax2.  Since IAX connections combine
+signalling, audio, and video into one UDP stream, it is not possible
+to set the TOS separately for the different types of traffic.
+
+In iaxprov.conf, there is a tos parameter that tells the IAXy what TOS
+to set on packets it generates.  As with the parameter in iax.conf,
+IAX packets generated by an IAXy cannot have different TOS settings
+based upon the type of packet.  However different IAXy devices can
+have different TOS settings.
+
+The allowable values for any of the tos* parameters are:
+
+be (best effort), cs1, af11, af12, af13, cs2, af21, af22, af23, cs3,
+af31, af32, af33, cs4, af41, af42, af42, ef (expedited forwarding),
+lowdelay, throughput, reliability, mincost, none
+
+The tos* parameters also take numeric values.
+
+The lowdelay, throughput, reliability, mincost, and none values are
+deprecated because they set the IP TOS using the outdated "IP
+prececence" model as defined in RFC 791 and RFC 1349.
+
+===========================================
+Configuation	Parameter	Recommended
+File				Setting
+-------------------------------------------
+sip.conf	tos_sip		cs3
+sip.conf	tos_audio	ef
+sip.conf	tos_video	af41
+-------------------------------------------
+iax.conf	tos		ef
+-------------------------------------------
+iaxprov.conf	tos		ef
+===========================================
+
+To get the most out of setting the TOS on packets generated by
+Asterisk, you will need to ensure that your network handles packets
+with a TOS properly.  For Cisco devices, see the previously mentioned
+"Enterprise QoS Solution Reference Network Design Guide".  For Linux
+systems see the "Linux Advanced Routing & Traffic Control HOWTO" at
+<http://www.lartc.org/>.
+