NewTek NDI-PTZ1, Руководство по эксплуатации

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You will also see the Hardware and Firmware versions for your camera displayed in this area, along with its
unique serial number. Buttons just below allow you to update the installed firmware, modify the default
network password, or to power the device down (‘sleep’).
1.3.1
MULTICAST
FIGURE 15
Click Multicast to transmit video using multicast, rather than the default unicast method. A suitable Multicast
address is generated, but you can edit the result manually if you need to. To update the address to another
random value, click Generate Address. Please take time to consider the following information before enabling
this feature.
M
ULTICAST OR
U
NICAST
?
Multicast can seem like a bandwidth-saving miracle. Unlike
NDI’s default mode (unicast), multicast does not require a
unique stream from the source to each receiver. When using
unicast, each connection to the sender reduces the
bandwidth available by a similar amount.
By contrast, multicast connections do not add significantly
to the bandwidth required as connections multiply. You
could be forgiven for wondering why anyone would ever
turn this option off - yet, it is off by default. Why?
This is because multicast requires more careful network
configuration. While you might not notice any issues in a
simple network setting; a poorly configured environment
can have serious impact on more complex networks.

Specifically, it is essential that IGMP snooping be
enabled for each switch on the network. This lets the
device listen to traffic between other hosts, switches
and routers, and identify receiving ports using
various IP multicast streams.

In addition, we strongly recommend that all
network switches be of the ‘managed’ type (see the
sidebar “Managed vs. Un-managed”).
Managed vs. Unmanaged
An un-managed (a.k.a., ‘dumb’) network
switch will cause a multicast stream to
revert to unicast. This can have serious
ramifications.
For example, even though a device
broadcasts a multicast stream, the un-
managed switch will pass unicast
packets to downstream switches and
clients. This can flood parts of the
network with unnecessary traffic. It can
even slow down the rest of the network,
as upstream devices are forced to wait
for responses from the over-saturated
devices.
The net result of such a poor setup can
be likened to a self-inflicted denial of
service attack.