Controls in the Network Settings section will be familiar to anyone who has connected a computer or mobile device to a network, and require little explanation.
Note: Wifi connections can produce very acceptable results, but performance issues may arise when many devices are connected. The radio in a wifi router can only listen to one device at a time, forcing other devices to wait and retry repeatedly. This problem worsens as more transmitters are added. Too, the portion of the radio spectrum you are using may be serving numerous wireless networks in the same vicinity.
A dedicated network helps minimize problems, as does careful channel selection – but a wired connection is always preferable in mission-critical settings.
Typically, your network will be configured to automatically supply IP addresses to devices you connect to it by means of a DHCP server. Your Spark’s IP Address resolution method is set to Dynamic by default, to take advantage of this scheme. To assign a static IP address to your Spark, change the IP Address setting to Manual.
NOTE: Should Spark’s default IP Address setting (Dynamic) fail to provide a usable IP address within a minute or two – as when an active DHCP server is not found on the network – Spark will automatically switch to Manual mode and attempt to connect using a static IP address. In this context, please read the section entitled “Local-Link (Failsafe)” for additional information.
Click Multicast (Figure 1-14) 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.
MULTICAST OR UNICAST? 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 unmanaged 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.
Spark’s Local-Link feature provides a convenient supplemental method of connecting to the device, should problems be encountered that prevent connecting by other means, or for other reasons. It may help to think of this as a failsafe connection method.
The Static IP Address entered in this section defaults to 192.168.100.168, and is always active. That is, even when a different static address is operative in the main Ethernet control group, or DHCP is supplying the primary IP address automatically, the Local-Link address will also work – even simultaneously.
That is to say that, if you connect a computer on the same domain (192.168.100.#) and with a matching net mask entry to the device in a peer-to-peer configuration, you will be able to access Spark’s web page by entering 192.168.100.168 into the browser’s address bar. You can then to modify your Spark password, or make other network configuration changes as desired.
Hint: It is not difficult to temporarily re-assign a computer to the Local Link network domain and make a direct, peer-to-peer connection to Spark using an Ethernet cable; but if you are not familiar with the procedures involved, you may wish to obtain the assistance of a network technician.
For more information, please refer to the Connect Spark User guide http://new.tk/NCSGuide