Configuring QoS settings

Quality of Service (QoS) settings are defined on the Network > QoS page to set priorities for outbound traffic from the MCU. They are specified as 6-bit binary values (tags) in the Type of Service header field for IPv4 or the Traffic Class header field for IPv6, and can be interpreted by networks as Type of Service (ToS) or Differentiated Services (DiffServ).

QoS tags are supported for every IP packet type transmitted by the MCU: media (audio and video), streaming, signaling, and administration.

CAUTION: We advise you not to alter QoS settings unless you have specific requirements to do so.

Note: In a cluster, a slave MCU only tags OA&M (Operations, Administration, and Maintenance) types of traffic because the master MCU handles all other types of traffic on behalf of the cluster, and does the QoS tagging for those types. You can change the slave's OA&M QoS value on the slave's Network > QoS page.

QoS tags

Field (tag)	Defines priority for...
Audio	Audio data packets, including RTP and RTCP streams.
Video	Video data packets, including FECC, BFCP, RTP, and RTCP streams.
Signaling	H.225, H.245, and SIP signaling packets.
OA&M	Operations, Administration, and Maintenance packets, including HTTP, HTTPS, FTP, DNS, syslog, OCSP, and NTP traffic.

Any traffic that is not covered by one of these categories is tagged as OA&M.

ToS configuration

ToS uses six out of a possible eight bits. The MCU allows you to set bits 0 to 5, and places zeros for bits 6 and 7.

Bits 0-2 set IP precedence (the priority of the packet).
Bit 3 sets delay: 0 = normal delay, 1 = low delay.
Bit 4 sets throughput: 0 = normal throughput, 1 = high throughput.
Bit 5 sets reliability: 0 = normal reliability, 1 = high reliability.
Bits 6-7 are reserved for future use and cannot be set using the MCU interface.

ToS configuration represents a tradeoff between precedence, delay, throughput, and reliability. Ensure that you maintain a balance when prioritizing packets, so that other packets on the network are not subject to undue delay (so for example, do not set every value to 1).

DiffServ configuration

DiffServ uses six out of a possible eight bits to set a codepoint. There are 64 possible codepoints. The MCU allows you to set bits 0 to 5, and places zeros for bits 6 and 7. The codepoint is interpreted by DiffServ nodes to determine how the packet is treated.

Default values

These are the default QoS settings on the MCU:

Audio 101110
- For ToS, this means IP precedence is set to 5 giving relatively high priority. Delay is set to low, throughput is set to high, and reliability is set to normal.
- For DiffServ, this means expedited forwarding.
Video 100010
- For ToS, this means IP precedence is set to 4 giving quite high priority (but not as high as the audio precedence). Delay is set to normal, throughput is set to high, and reliability is set to normal.
- For DiffServ, this means assured forwarding (codepoint 41).
Signaling 000000
Admin 000000

To revert to default values, click Reset to default.

Changes to QoS settings require a reboot to take effect.

More information

For more information about QoS, including ToS and DiffServ values, see the relevant RFCs on the Internet Engineering Task Force web site www.ietf.org: