Telos Zephyr Xstream - Manual (Page 161)

USER’S MANUAL
Section 8: LIVEWIRE TM – IP Audio 149
801.1p tagging, 802.1p VLAN ID, 802.1q Priority, & DSCP Class of Service
802.1p tagging is necessary within the Livewire network to mark high‐priority audio packets.
This information is used by the Ethernet switches in the packet scheduling and queuing
mechanism. It provides low‐jitter packet forwarding of Livewire clock and low‐latency audio
streams.
On the other hand, Standard streams don’t need tagging, because they are not low‐latency. By
default, standard streams are marked with Type of Service (DSCP code points) information in
the IP header which can be used by L3 switches to provide better service to our audio streams
than to best effort IP traffic.
There is an option to enable L2 802.1p tagging on standard streams, and this may be used with
switches which do not use the DSCP information included in the TOS field of the IP header. We
do not enable this
tagging by default, because it wouldn’t work in cross‐over Ethernet
connection to PCs; most network cards do not accept 802.1p frames by default.
You should not need to change these default settings unless you are building a system which is
not based on our recommendations.
In Axia nodes and the Xstream, the VLAN ID setting is a read‐only value. It is always 0 and
cannot be changed. As a result Livewire audio always uses the native VLAN assigned to the port
of the switch.
“DSCP Class of Service” is a standard describing the tagging of IP frames with service
information. Network equipment can be set up to provide different forwarding delay and drop
precedence depending on the service information. Our defaults are compatible with most
Ethernet equipment defaults for class of service Livewire requires; you should not need to
change them unless instructed by Axia Support.
8.2 Livewire Audio Settings
There are two ways to setup Livewire audio, Basic Mode (shown by default) and Expert Mode.
The difference between these two modes is that Expert Mode allows you to customize the
codec backfeeds. We will take a look at both scenarios.
Livewire Configuration – Basic Mode
This mode will be fully adequate for most users. It assumes the default backfeed for the codec.
This is the automatic mix‐minus created by the mix engine and will consist of the PGM or AUX
bus as configured on your Element or other control surface.
In this example, the sources being delivered to the Livewire network have been identified as ZXS
SRC 1 and ZXS SRC 2. These are simply name tags and they can be virtually anything you want.
We suggest you make them descriptive and unique so you will be able to easily determine the
source if you have multiple Xstream codecs in your facility.
The channel numbers that you specify must be carefully chosen. They must be unique since
duplicate channel numbers in a Livewire network will result in multicast collisions and “less than