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77 lines
2.8 KiB
Plaintext
77 lines
2.8 KiB
Plaintext
IP Type of Service settings for VoIP channels
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---------------------------------------------
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Asterisk can set the Type of Service (TOS) byte on outgoing IP packets
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for various protocols. The TOS byte is used by the network to provide
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some level of Quality of Service (QoS) even if the network is
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congested with other traffic.
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* SIP
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-----
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In sip.conf, there are three parameters that control the TOS settings:
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"tos_sip", "tos_audio", and "tos_video". tos_sip controls what TOS SIP call
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signalling packets are set to. tos_audio controls what TOS RTP audio
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packets are set to. tos_video controls what TOS RTP video packets are
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set to.
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* IAX2
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------
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In iax.conf, there is a "tos" parameter that sets the global default TOS
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for IAX packets generated by chan_iax2. Since IAX connections combine
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signalling, audio, and video into one UDP stream, it is not possible
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to set the TOS separately for the different types of traffic.
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In iaxprov.conf, there is a "tos" parameter that tells the IAXy what TOS
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to set on packets it generates. As with the parameter in iax.conf,
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IAX packets generated by an IAXy cannot have different TOS settings
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based upon the type of packet. However different IAXy devices can
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have different TOS settings.
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The allowable values for any of the tos* parameters are:
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CS0, CS1, CS2, CS3, CS4, CS5, CS6, CS7, AF11, AF12, AF13,
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AF21, AF22, AF23, AF31, AF32, AF33, AF41, AF42, AF43 and
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ef (expedited forwarding),
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The tos* parameters also take numeric values.
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The lowdelay, throughput, reliability, mincost, and none values are no
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longer supported in this version of Asterisk.
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===========================================
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Configuration Parameter Recommended
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File Setting
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-------------------------------------------
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sip.conf tos_sip cs3
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sip.conf tos_audio ef
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sip.conf tos_video af41
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-------------------------------------------
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iax.conf tos ef
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-------------------------------------------
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iaxprov.conf tos ef
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===========================================
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* REFERENCE
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-----------
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RFC 2474 - "Definition of the Differentiated Services Field
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(DS field) in the IPv4 and IPv6 Headers", Nichols, K., et al,
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December 1998.
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IANA Assignments, DSCP registry
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Differentiated Services Field Codepoints
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http://www.iana.org/assignments/dscp-registry
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To get the most out of setting the TOS on packets generated by
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Asterisk, you will need to ensure that your network handles packets
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with a TOS properly. For Cisco devices, see the previously mentioned
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"Enterprise QoS Solution Reference Network Design Guide". For Linux
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systems see the "Linux Advanced Routing & Traffic Control HOWTO" at
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<http://www.lartc.org/>.
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For more information on Quality of
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Service for VoIP networks see the "Enterprise QoS Solution Reference
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Network Design Guide" version 3.3 from Cisco at:
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<http://www.cisco.com/application/pdf/en/us/guest/netsol/ns432/c649/ccmigration_09186a008049b062.pdf>
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