Cirrus Logic CobraNet - Manual (Page 16)

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Copyright 2006 Cirrus Logic, Inc. DS651PM25
CobraNet Programmer’s Reference
Network Stack
3. Network Stack
Figure 5. CobraNet Network Stack
3.1 CobraNet Audio
This includes transmission and reception of audio data packets and reservation requests,
implementation of conductor arbitration, and the ability to serve in either conductor or
performer roles. CobraNet audio is a self-contained service that spans from Logical Link
(2) to Application (7) layers.
3.2 Serial Bridge
This service provides bridging of asynchronous serial streams over the Ethernet network.
This self-contained service spans from the logical link to the Application layer. The serial
bridge service is discussed in
Section 2.1 "Serial Bridge" on page 12 .
3.3 Packet Bridge
This service simply allows the CobraNet interface to operate as an Ethernet controller for
a connected host. This service works at the logical link layer and provides access to the
network without providing any actual network services. The packet bridge feature is
discussed in
Section 2.2 "Packet Bridge" on page 13 .
3.4 BOOTP
The boot protocol (BOOTP) is supported as specified in RFCs 951 and 1542. Network
clients use BOOTP to receive an IP address from a BOOTP server.
Clients needing an IP address will broadcast a BOOTP request packet. A BOOTP server
on the network will respond with a BOOTP response containing the preferred IP address
for the client to use. Use of BOOTP simplifies the error-prone task of assigning unique IP
addresses to devices on a large network. BOOTP is carried via UDP/IP and, as such, is
able to pass through properly configured routers.
BOOTP requests are transmitted by the CobraNet interface on a randomized schedule as
recommended in the RFCs. Requests are sent out frequently at startup and then taper
CobraNet Services Internet Protocol Suite
Fast Ethernet Interface
802.3 Ethernet
IP RARP ARP
UDP
BOOTP SNMP TFTP
ICMP
Packet
Bridge
CobraNet
Audio
Serial
Bridge
Physical
Logical Link
Network
Transport
Application