Lesson Description
Part B: Network Protocols
4m 28s
Understand the difference between protocols such as TCP and UDP, as well as learn the importance of a Gigabit network and using compliant switches.
Video Transcript
Part B: Network Protocols
4m 28s
0:08
Welcome back. In the last section we covered the OSI 7-Layer model. Now within this framework,
0:14
there are a few different protocols for sending information. Transmission Control Protocol,…
0:19
…or TCP, adds acknowledgement and sequential delivery information to data that allows
0:24
the receiving end to confirm delivery of each data segment
0:27
and return that information to the sender before allowing the next segment to be sent
0:31
this ensures that there is no loss of packets, but also increases bandwidth and time.
0:36
Q-Sys sends most of its control information using TCP, but it handles its audio streaming using UDP,
0:42
or User Datagram Protocol. UDP does not wait for the receiving end to confirm delivery
0:48
it simply continues to send all information as it comes in.
0:51
It should be obvious why audio is streamed this way.
0:54
You don’t want to break up or slow the music down by waiting for delivery of every data segment.
0:59
If you’ve ever tried to watch an online video that hasn’t been buffered …
1:05
Ohhh! What? … you know what I’m talking about. Ohhhhh!
1:11
And if UDP does end up dropping a few packets here and there, don’t worry about it
1:14
the software corrects and covers for those packets and you’ll never even know it happened.
1:19
In addition, Q-Sys also uses its own multicast protocol known as QDP,
1:24
which allows all the devices to identify each other on the network.
1:27
This is how you can discover your inventory in the Q-Sys Configurator,
1:31
which has its own tutorial. The speed of the network is important in letting Q-Sys get its task done.
1:37
In order to maintain a complete network latency of less than 250 microseconds, a Gigabit network is required.
1:44
Consider if it takes 12 microseconds for data to travel along a cable on a Gigabit network…
1:50
…that would become 120 microseconds on a 100Mb network.
1:54
Going through a switch takes 12 microseconds to enter and 10 microseconds
1:58
for the switch to decide where to send the data. So if you have even one switch hop in your path,
2:03
you’re already above 250 microseconds of latency. That’s why a Gigabit network is required.
2:10
Q-Sys can use up to 84% of a Gigabit network, using 1.54 MB a channel.
2:16
When you’re choosing which switches to use,
2:18
keep in mind that your switch must have wire-speed non blocking delivery,
2:22
with at least 40 kb of dedicated buffering per port.
2:26
And the total switch fabric must be greater than the port quantity
2:30
meaning that if you have 8-ports on a gigabit switch, the total switch fabric must be able to handle 8 Gb.
2:36
Additionally, your system must be able to support DiffServ, or 802.1p QOS
2:42
that stands for Quality of Service – which categorizes and prioritizes network traffic,
2:46
allowing Q-Sys to operate on a shared network without segregating audio traffic with tedious VLAN configuration.
2:53
All of this information should be readily listed on the spec sheet for your switches and routers
2:58
and a complete list of compliancy approved switches are available at QSC’s website.
3:03
Q-Sys also accommodates fully redundant networking configuration,
3:07
including all standard Layer 3 fault-tolerance strategies such as spanning tree.
3:12
Spanning Tree Protocol, or STP, is a method of enabling
3:16
and disabling redundant paths on a network to avoid signal loops.
3:22
A data loop can be disastrous to a network as it floods the bandwidth and can bring all traffic to a stop.
3:27
Spanning tree establishes a quickest-path map for data to get through each
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switch on a network and disables the alternate paths.
3:35
Then, if a connection fails, it dynamically changes which paths are open to create a new path,
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while still protecting from signal loops that could lead to infinite flooding, or a broadcast storm.
3:46
Now this has obviously just been a skimming of the surface when it comes to networking
3:51
but hopefully it gives you an idea of how Q-Sys exists in a network.
3:54
Most of this information happens invisibly without you ever having to worry about it
3:59
but if you do have to worry about it, hopefully you can work with your IT partners
4:03
and they’ll know a lot more about it.
4:05
Once your devices are properly connected to the network,
4:08
they’ll be discoverable by the Q-Sys Designer software
4:10
and you’ll be able to integrate them into your audio design.
4:13
Now to do this, you’ll need to configure them with the Q-Sys Configurator,
4:17
which will be the focus of the next section. So feel free to take a short break here,
4:23
and we’ll come on back whenever you’re ready.
Helpful Tips and Definitions
Part B: Network Protocols
4m 28s
- Q-LAN requires a Gigabit network to maintain its latency beneath 250 us
TCP (Transmission Control Protocol): Confirms delivery of each data segments before requesting the next in the sequence
UDP (User Datagram Protocol): Sends each data segment as it is received regardless of confirmatio
QDP: Multicast protocol that identifies Q-Sys devices on the network
STP (Spanning Tree Protocol): Layer 2 Protocol designed to prevent data loops in a switched network
Downloads and Links
Part B: Network Protocols
4m 28s