Visionary, Network Audio Video
DUETE-2/DuetD-2 USER MANUAL
NETWORK AV INFRASTRUCTURE PREREQUISITES
Because multicasting video traffic can flood a network and
significantly
reduce the flow of traffic, it is important to ensure that
your
network infrastructure
and
backbone
switches support IGMP
Snooping
so that your core network is able to ignore the traffic
streams multicasting can generate. By default, all multicast traffic should be blocked until requested by a multicast
group
member.
Without IGMP Querying/Snooping, multicast traffic is treated in the same manner as a broadcast transmission, which
forwards packets to
all ports on the network. With IGMP Querying/Snooping, multicast traffic is only forwarded to ports
that
are
members of that multicast group. IGMP Snooping generates no additional network traffic, which significantly reduces the
multicast traffic passing through your switch.
Note: Some
switches
require that the routing table be
pre-loaded
so that the
switch
does not have to
interrogate
each IP packet to
determine its
destination.
Static routing can be used to route multicast traffic.
Protocols
similar to Generic Routing Encapsulation
(GRE) can be used to
encapsulate
multicast packets in unicast wrappers for
point-to-point transmission
between switches, and
when the packets arrive at the destination IP address, the unicast wrapper is removed.
2. Enable Fast Leave. The switch may also support IGMP
Snooping
Fast Leave, which shortens the time takes for a device to leave a
group and be made available to join to a different group. A switch can be informed that a device wants to leave a multicast
channel by sending it a IGMP Leave Group packet. Once received, the time it takes for the switch to apply the new configuration
may vary from one switch to another. Most switches have a Fastleave configuration option. When enabled, Fastleave speeds up
the time neede
d for a port assigned to one multicast group to leave the group and join a different multicast group. This
significantly reduces the video switching time. Always enable the Fastleave option when it is available.
3. Allow multicast traffic on all network ports through which video streams pass.
4. Ensure current Access Control Lists (ACLs) are not filtering multicast or control traffic.
5. Remove Flow Control and/or Storm Control on any network port passing the video stream.
6. Enable VLANs to separate video traffic from data and voice.
7. Enable Jumbo Frames.
8. Disable Green Ethernet (or efficiency mode). Some switches have the ability to lower the power consumption on the ports as a
“Green” feature. This can cause issues with bandwidth intensive devices (like our encoders and decoders).
IMPLEMENTATION CONSIDERATIONS
Duet-2 devices can be installed on a physically separate network or converged onto an existing GbE network. When implementing, it
is important to decide at the earliest stages of planning if the system will be integrated into the rest of the network or if it will reside
on a dedicated AV network. Each has its own advantages and disadvantages, but wherever possible we recommend the use
of a
dedicated AV switch. Using the existing network is of course possible–but it adds extra complexity to the installation and often
removes control of the networking equipment from the
site’s AV staff or installer.
The first thing to consider is how much control the install and site teams have over the network configuration. Do they have access
and clearance to change the managed switch configurations on the fly? Is the network administrator willing to make the necessary
changes to support multicast and IGMP traffic on their network? Will they allow the creation of a VLAN or change their existing
VLAN configuration to support the required configuration? If the answer to these questions is no, then it is highly recommended that
the system be installed on a sepa
rate dedicated network switch. If this is not an option, then a conversation needs to take place with
the network admin staff to ensure they are aware of the requirements.
INSTALLING ON A CONVERGED NETWORK
Figure 1 illustrates how Duet-2 endpoints can be installed on an existing (converged) network. When using an existing
infrastructure, dedicated VLANs are recommended to separate the Dante™ and video traffic from other network data. All switches
that will handle AV traffic must be 1 GbE capable per the specifications in Network Requirements.
Visionary Solutions recommends that all encoders be turned off before connecting to an existing network. Once connected,
encoders can be turned on one at a time to determine network impact.
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