Cirrus Logic CobraNet - Manual (Page 11)

CobraNet Programmer’s Reference
Overview
DS651PM25
©
Copyright 2006 Cirrus Logic, Inc. 11
1.4 Bundle Addressing types
Multicast bundles represent a least common denominator for audio interoperability in
CobraNet networks. Bundles sent with multicast destination addresses are delivered
indiscriminately to all CobraNet interfaces and thus have the potential of overloading a
network. Care should be taken to insure that an excessive number of multicast bundles
are not used. See
Bundle Assignments in CobraNet Systems (available for download at
www.cirrus.com ) for a discussion of issues associated with multicast bundles.
Unicast bundles are sent to only one destination on a network. However, in the event
that more than one CobraNet interface is set to receive the same bundle number, the
CobraNet protocol may, according to rules governed by the
txUniCastMode and
txMaxUnicast variables, cause unicast bundles to be sent as multicast or multi-unicast
when necessary. Multi-unicast will use unicast addressing to send up to four copies of the
same bundle to different CobraNet interfaces.The default configuration for
txUnicastMode
insures that unicast bundles are never multicast.
Private bundles are a special case of unicast or multicast bundles. The transmitter's
MAC address, in addition to the bundle number, is required to fully qualify a private
channel at the receiver. Like unicast bundles, these may be either unicast or multicast
based on
txUnicastMode.
Note: Transmitted bundles must have a unique bundle number assigned to them. More
than one transmitting interface cannot use the same bundle number. Multiple receiving
interfaces can receive the same bundles.
Table 2. Bundle Numbering
Hexadecimal
Bundle
Number
Decimal
Bundle Number
Designation Usage
Transmission
Addressing
Transmission
Mode
0 0 Null
Unused bundle. Disables
transmission/reception when
selected.
Never transmitted. Never transmitted.
1-0xFF 1-255 Multicast
Transmitted by a single
CobraNet interface and received
by any number of interfaces.
Always multicast
Always
transmitted.
0x100-
0xFEFF
256-65279 Unicast
Transmitted by a single
CobraNet interface. Dependent
on txUnicastMode and
txMaxUnicast settings may be
received at a single (default
case), a few (multiple unicast
case) or a large number
(multicast case) of interfaces.
Generally unicast
but may multicast if
txUnicastMode
variable is
adjusted.
Only transmitted
when at least one
receiver is
identified via
reverse
reservation.
0xFF00-
0xFFFF
65280-65535 Private
Individual transmitters locally
allocate private channels. The
bundle number is conditioned on
the transmitter's MAC address.
There are 256 of these bundles
per transmitter thus the total
number of private bundles is
virtually unlimited as the bundle
numbers are unique to a
particular MAC address.
Generally unicast
but may multicast if
txUnicastMode
variable is
adjusted.
Only transmitted
when at least one
receiver is
identified via
reverse
reservation.