Crown DBC NETWORK BRIDGE 137769-3 Operation Manual page 78

DBC Network Bridge
The MAC address does uniquely identify each TCP/IQ component and
can be used to establish the physical location of the unit. The binding of
the MAC address to the IQ address through the use of the TCP/IQ Utility
assures that each TCP/IQ component is physically in the right position.
The use of the IP address establishes the Local Area Network (LAN) and
what components reside within that LAN. The Subnet Mask associated
with each IQ Component tells what IP addresses can be assigned to a
particular LAN. The Subnet Mask is also four numbers (0-255) sepa-
rated by periods. For example, a subnet mask of 255.255.0.0 and an IP
address of 126.126.1.123 says that all IP addresses in that LAN are in
the IP address range of 126.126.1.1 to 126.126.1.255.
If a TCP/IQ controller is on a different network than the TCP/IQ compo-
nents, communications must occur through an IP router. TCP/IQ dis-
covery requires the use of broadcast Ethernet data packets onto the
network. These broadcast commands cannot be done through an IP
router, therefore a Discovery Proxy is required. The establishment of
this proxy is done in TCP/IQ by naming the IP address of a known com-
ponent on the component network as the Discovery Proxy within IQWin
Figure 8.3 Star Network Topology
or TCPIQ Util.
8.3 A Closer Look at CobraNet
CobraNet is a licensed technology developed by Peak Audio, Inc. con-
sisting of proprietary communications protocol, firmware and hardware.
It allows reliable, deterministic transmission of digital audio over a
100Base-T Fast-Ethernet network.
This section provides an overview of CobraNet. Peak Audio has pro-
vided a number of technical papers that describe CobraNet in detail.
These papers are available at http://www.PeakAudio.com.
8.3.1Fast Ethernet
(100Base-T)
Fast Ethernet (100Base-T) uses a hub to interconnect all network nodes
to form a star topology (see Figure 8.3). In the star topology all PCs are
connected to a centralized hub. Messages are sent from the originating
PC to the hub, which then transmits the message either to the whole
network or, if a switched hub is used, to the destination PC only. Hubs
may be active or switched.
In larger Fast Ethernet networks, additional hubs, concentrators, and
other network hardware are used to form a larger network, as shown in
Figure 8.4.
Figure 8.4 Multi-Star Topology
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