VX Enterprise and VX Prime+ QOS Settings

Updated by Bryan Jones

The QOS options on VX Enterprise and VX Prime+ are set through a configuration file named qos.cfg. This file is found at this location: /etc/local/telos_vx/qos.cfg . The general format of the file is similar to that of other configuration files.

For qos.cfg, the format is:

config.qos = {
  multicast_ttl: <default multicast TTL>,
  livewire: {
    <QoS options for Live Stereo streams>
  },
  standard: {
    <QoS options for Standard Stereo streams>
  },
  aes67: {
    <QoS options for AES67 streams>
    <Setting eth_prio and eth_vlan to 0 disables 802.1Q tag>
    eth_prio: 0,
    eth_vlan: 0
  }
};

The multicast_ttl sets the default TTL value for all multicast traffic (and also unicast AES67 streams when supported). The default value is 1. This can be overridden per stream type basis using the ip_ttl option if necessary.

The set of options supported for Livewire Live streams, Livewire Standard streams, and AES67 streams is mostly the same, with a few exceptions that are noted below:

  • eth_prio - IEEE 802.1p priority code point (0-7), default: 6 for Live, 5 for others
  • eth_vlan - IEEE 802.1Q VLAN tag (0-4094), default: 0
  • ip_ttl - IP TTL value (1-255), default: multicast_ttl if set, 1 otherwise
  • ip_dscp - IP Diff Serv Code Point (0-63), default: 48 for Live, 46 for Standard, 34 for AES67
  • ip_dontfrag - Set IP DF bit (Standard & AES67 only), default: true
  • recv_buf - Receive buffer size in microseconds (2000-20000, AES67 only), default: 3000

All settings are optional, including subsections. For example, to set TTL only, the following is sufficient:

config.qos = {
  multicast_ttl: 127
};

The order of settings doesn't matter, and invalid and unknown options are ignored, but retained. Hexadecimal values prefixed with 0x are supported for all options taking a numeric value.

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