Renkus-Heinz RHAON 32-Bit - Manual (Page 46)

Users Manual
46
SERVICING and TROUBLE SHOOTING (Continued)
Lesson 2: Packet Addressing
On a Local Area Network (LAN), packets are addressed by the Media Access Control (MAC) address of the network device. MAC ad-
dresses are “burnt-in” by the manufacturer of your network device (computer network card, RHAON loudspeaker, etc.) and are globally
unique. This is like the VIN on your car. No matter where you register your car, the VIN stays the same and is unlike that for any other
vehicle worldwide.
In order to address different devices on different networks, Internet Protocol (IP) addresses were introduced. They allow for easier routing
for a vast array of interconnected networks. Similar to this is the license plate on a car. Rather than attempting to search for the car by
going through the VINs for every car in the world, one could narrow things down by first selecting the country in which it was registered and
then by license plate number within that country. RHAON acts as the license plate authority, if a CobraNet device (RHAON speaker, mixer,
etc.) doesn’t yet have a “license plate”, it asks RHAON for one and the software kindly obliges.
Packets addressed by MAC address are known as “Ethernet packets”. In addition to information about the source and destination and the
payload, there is a marker for what type of Ethernet packet is being sent. IP packets (ones that can be sent within or out of the LAN) have
one identifier and CobraNet packets have another. Because CobraNet packets don’t contain IP information in their payload, CobraNet is
limited to being LAN-only. The structure of an IP packet is very similar, in that it contains - among other information - a source address,
a destination address, and protocol type. For RHAON, the protocol types of UDP and TCP are the ones in heavy use. Building upon
the UDP protocol is the Simple Network Management Protocol (SNMP), which is what RHAON uses to monitor or manipulate exposed
variables (EQ, Bundle Assignments, etc.) on a RHAON loudspeaker or other CobraNet device. At each stage in the process of handling a
packet, the previous layer is left behind. Once a payload type is determined, just that payload is handed off to the appropriate handler.
To better understand what takes place when RHAON tells a loudspeaker “Set Gain to -10 dB”, think of Russian nested dolls. Your com-
puter will send out the whole doll, which contains an IP doll, which contains a UDP doll, which contains an SNMP doll, which contains the
message “Set Gain to -10 dB”. When a device sends out a piece of CobraNet audio, it sends out a whole doll, which contains a CobraNet
doll, which contains the piece of audio.
With CobraNet, since both devices have a ‘burnt-in’ MAC address, communication can happen right away. For SNMP communication
between the computer and RHAON loudspeaker to happen, both devices must have a valid IP address. In most home or office networks,
there is a device called a ‘router’ that not only contains a network switch, but can also handle the assignment of IP addresses within its
network through a protocol called DHCP. CobraNet (and, by extension, RHAON) uses a different protocol for requesting / assigning IP
addresses, but the end result is still the same. Your router has a static IP address assigned to it, devices ask it for an IP, and the router
obliges. For this same reason you must assign a static IP address to your computer.
Troubleshooting Tips
Since RHAON relies on standard networking communications and hardware along with CobraNet, general networking and CobraNet
troubleshooting documents can also be of assistance in solving problems. Don’t throw away any documentation related to the network
switches or CobraNet source devices.
If you are familiar with CobraNet Discovery, you may also want to install and use it as a supplement to the RHAON Network Manager.
CobraNet Discovery is a network management program similar to the RHAON Network Manager. Both are invaluable in identifying and
solving network problems.
If you don’t have CobraNet Discovery, you can download it at no cost from our ftp site, hftp://ftp.renkus-heinz.com/Software/CNDisco345.
exe The Discovery program was also included on the RHAON CD you received with your loudspeaker.