Rane NM 48 - Manual (Page 9)

Manual-9
Network Examples
There are two ways to transmit CobraNet audio across a
network. An example for each transmission method follows.
The application dictates which of the two methods to use.
Some applications may require both methods simultaneously.
Multicast Network example [a.k.a. broadcast]
requiring simpler repeater hubs
One way to transmit audio over the network is to allow all
of a device’s audio channels to be transmitted to all devices.
This is called multicast in network lingo and can be thought
of using the more familiar term: broadcast. Thus, when you
transmit audio using one of the Multicast Bundles (Bundles 1
through 255), the audio is broadcast to every device on the
network.
This broadcasting of all channels everywhere is required
for applications such as paging when emergency audio must
be delivered to every node. When users at each node need
independent access to all available audio channels, use
Multicast Bundles. If your application is a large music
complex with many audio channels and all the audio channels
are required in all rooms or nodes, use a multicast network by
selecting Multicast Bundles 1 through 255 for audio transmis-
sion.
One advantage when using Multicast Bundles is that an
unlimited number of receivers (CobraNet devices) are
allowed for a single transmission with no additional network
bandwidth being consumed. This is just like radio broadcasts:
one transmitter, unlimited receivers.
Another advantage is the lower cost and complexity
network that is required to implement the audio system using
Multicast Bundles which are implemented utilizing simple
Ethernet repeater hubs, which are quite inexpensive. This
makes this Multicast application and system a “Networking
101” example – inexpensive and easily implemented.
The disadvantages of Multicast Bundles include the loss
of bandwidth network-wide, since every device and every
network cable contains the same quantity of data. All
multicast data takes up the same amount of bandwidth
throughout the entire network. Another thing to be cautious of
is that multicast CobraNet data will swamp any 10 megabit
(10Base-T) data ports on the network.
Modern computers with 100 Mbit PCI Ethernet interfaces
(100Base-T) are quite capable of ignoring this multicast
traffic until their network connection becomes saturated.
However, if the computer is connected to the network via 10
Bundle number Designation Description Advantages Disadvantages
0 (Off)
(hex: $00)
Null Transmission disabled.
Unused channel, i.e.,
Off. Perfect for muting audio and
saving network bandwidth.
Muted audio never arrives
at any destination and is
nearly impossible to hear.
1 through 255
(hex: $0001
through $00FF)
Multicast Bundle Multicast. All CobraNet
devices can transmit &
receive data through
Multicast Bundles. Allows an unlimited number
of receivers per transmission
with no additional network
bandwidth consumed.
[On a CobraNet network, all
CobraNet and non-CobraNet devices,
such as repeater hubs, receive all
Multicast data.]
Consumes resources
(bandwidth) network-
wide*. Only 32 Multicast
Bundles allowed per
VLAN when using
managed switches.
Swamps all 10 Mbit ports
on the network. [*Fixed
maximum of 8 Bundles using
repeater hub networks. Do not
mix computer data and CobraNet
data on a repeater network.]
256 through
65,279
(hex: $0100
through $FEFF)
Unicast Bundle Unicast (i.e., point-to-
point) data transmission.
[With some serious SNMP
work, Unicast Bundles can be
setup as multicast - this does
not mean you'll ever need to
do it though. This is also why
Multicast Bundles exist.]
There is no fixed maximum
number of Bundles on
switched networks. Computer
data and CobraNet data can
more efficiently and reliably
exist on the same network.
Greatly improves network
data throughput and
efficiency since data is only
passed from point to point
and not to every network
device. Allows 10 Mbit ports
(such as the Rane Via 10).
Cannot send one device's
audio to more than one
other device without using
a second independent
Bundle.
[The NM 84 allows the
same 8 Audio Channels to be
transmitted on up to 4 different
Bundles - which is the maximum
allowable by CobraNet devices.]
Table 1. CobraNet Bundles