QSC Q-SYS Installation and operating instructions

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Application Note
Q-SysTM Networking Overview
Figure A1
Date: 01/18/2011
Revision: A
Author: Scott Kalarchik
The intention of this document is to provide network
administrators an overview of the requirements needed to
implement a Q-Sys Audio System on a converged network. In
order to simplify this group of networking requirements for
ease of communication between parties, QSC has named these
requirements the “Q-LAN Protocol Suite”.
Overview of Q-Sys
Q-Sys is a system that performs complex routing, processing and
management of audio in a facility. The elements of a Q-Sys system:
• The Core is based on an Intel™ server processor. It runs the
system and handles the signal processing functions.
• I/O Frames are connected to the Core via the network and
provide a means for audio signals to be brought into the
Core from analog and digital sources as well as sending the
processed audio to power amplifiers, powered loudspeakers
or other audio devices. The I/O Frames are fitted with cards
appropriate to the types of inputs and outputs they will receive
or send.
• Peripheral devices including Page Stations and Touch Screen
Controllers may also be used in a system.
• Q-Sys Designer software is used by the system designer to
create signal flows, processing and control screens for a system.
Layer-3 Networking
All Q-Sys network protocols are Internet Protocol (IP) based and
support advanced networks beyond the simple Layer-2 LAN.
Because Q-Sys is a live system, real-time performance is required
on either the LAN or the Layer-3 environments. On a Layer-3
network, routers replace some, or all, of the network switches.
Therefore, routers need to have the same performance and
feature requirements as the switches they replace.
Q-LAN Protocol Suite
Sampling Clock
• IEEE 1588 Precision Time Protocol (PTP) used for synchronisation
• UDP on Ports 319 and 320
• ≤100 packets per second
• ≤100 bytes per packet
• 224.0.1.129 ~ 224.0.1.132 – registered to IEEE
• Address used depends on clock configuration selected in
the Designer software
Q-Sys™ Core
Up to 16
Audio Sources
I/O Frame I/O Frame I/O Frame
QSC DataPort
Amplifiers
QSC
Loudspeakers QSC
Loudspeakers
QSC DataPort
Amplifiers
Gigabit Switch
Q-Sys™ Core
AES Digital Audio

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Audio Streams
• UDP on Ports 6511 through 6766 as needed
• Each packet contains 16 samples of up to 16 channels
• 3000 packets per second per stream
• 100 to 1100 bytes per packet or 1.65 ~ 3.31 Mbps per stream – packet
size depends on channel count
• Audio sampling is 32 bit floating point format
• Up to 128 streams in and out of each Q-Sys Core
• 1 Stream in and/or out for each I/O Frame or Page Station
• 100 acknowledgements are sent every second and contain
receiver-side stats
Control
• TCP and HTTP for Control Data and Core redundancy
• 1 Mbps or less – dependant on connections to User Control Interfaces
(UCI’s) or AMX and Crestron
QoS
• Ensures timely delivery of packets
• Employs DiffServ or Differentiated Services Code Point (DSCP)
• DSCP 63 normally reserved for Network Admin
• DSPC 46 EF (Expedited Forwarding) for PTP
• DSPC 34 AF (Assured Forwarding) for Audio data
• DSPC 0 for control data
• Minimum of 4 egress queues per switch port with Strict Priority
Queuing – other selection schemes (e.g. round robin, shaped
round robin, fair queuing, guaranteed minimum bandwidth) are
not recommended
• Each Q-Sys switch port must have 40kB of egress queue
memory available
• Note: Don’t enable bandwidth throttling on ports connected
to the Cores
QDP and Multicast Routing
• For Q-Sys to work across a Layer-3 network, you will need to
configure the network to route the multicast addresses used
by the PTP Clock and Discovery protocols. Q-Sys devices
implement the Internet Group Management Protocol (IGMP).
IGMP allows Q-Sys devices to register to receive specific
multicast addresses.
• QDP – Device Discovery – 224.0.23.175 – registered to QSC
• – Used to find Q-Sys products on the network by name
regardless of IP address
• IEEE 1588 – 224.0.1.129 ~ 224.0.1.132 – Registered to IEEE
Latency
• Time on Wire @ 1 GB ≤12 micro seconds
• Time on Switch @ 1 GB ≤10 micro seconds
• Allowed Time on Network = 243 micro seconds
• Option to increased buffer size for larger networks
via Designer software
Switch Requirements
• Must be a managed, non-blocking Gigabit switch with
bandwidth meeting or exceeding “wire speed” bridging
• Must support DiffServ QoS
• Packet forwarding delay of less than 10 micro seconds
• No Jumbo frames on any Q-LAN paths
Bandwidth Usage
• Bandwidth equation: Mb = (1.77 x total stream count) + (1.54 x
total channel count)
• Dual network redundant configurations will produce the same
bandwidth on both ports

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• Core bandwidth calculations are available on the “Check
Design...” screen in the Designer software
• Core to Core redundant housekeeping data can be up to 6
Mbps when a Q-Sys System is being polled by AMX or Crestron
IP Address
• Three methods are use to assign IP’s: Manual, DHCP, or IPv4LL
(Auto-IP) – QSC recommends using Manual IP’s
End Point Device Routing
This allows a device on one subnet to communicate with a device
on separate subnet. There are two methods used to accomplish
this task – a static route or the default gateway. A static route
defines a specific destination/mask pair. The default gateway is a
“catchall” for everything which doesn’t match a static route. Here’s
an example of a static routing configuration using the “Q-Sys
Configurator...” screen in the Designer software:
To see if Discovery and routing are working on the Core, enter the
following URL into any web browser: http://<core-ip-address>/
discovery/discovered and confirm there are files called “device.
ioframe.<ioframe-name>” for each I/O Frame
If you have any questions or need additional assistance, please contact
your local QSC representative, QSC’s sales department or myself.
Scott Kalarchik, CCNA & CCDA
Director, Engineered Systems
QSC Audio Products, LLC
1665 MacArthur Blvd
Costa Mesa CA 92626
Phone [phone]
Cell 714-269-4231
Fax [phone]
Email [email protected]
Web www.qscaudio.com

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Passionate About Sound
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