Cirrus Logic CobraNet - Manual (Page 18)

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Copyright 2006 Cirrus Logic, Inc. DS651PM25
CobraNet Programmer’s Reference
Network Stack
The CobraNet implementation of IP has the following limitations:
• Segmentation and reassembly is not supported. Segmentation is primarily
utilized by stream based TCP protocols that can generate large data packets.
Reassembly capability can be necessary on heterogeneous networks (those
comprising multiple network technologies such as Ethernet, FDDI, and ISDN).
• Cannot initiate IP communications; can only respond to incoming messages.
The CobraNet implementation does not support net mask and default gateway
concepts required to initiate communications to other subnets. Furthermore,
CobraNet's implementation of ARP does not support generation of ARP
requests.
3.9 UDP
User datagram protocol (UDP) is defined in RFC 768. UDP is a transport protocol (layer 4
of the OSI 7-layer networking model) responsible for maintaining the integrity of data.
UDP is an extremely simple protocol which, by design, defers the data integrity problem to
application protocols in higher network layers.
CobraNet fully supports UDP.
3.10 TFTP
Trivial file transfer protocol (TFTP) is defined in RFC 783. TFTP supports file read and
write via a UDP/IP transport. The CobraNet implementation of TFTP supports only binary
reads and writes to a specific set of files. This is the mechanism used to update firmware
in a CobraNet interface. The TFTP file names correspond to the different sectors of the
FLASH memory and can differ in name and size for different revisions of CobraNet
interface hardware.
Firmware update is a complex process best accomplished by use of an encapsulated
software module, such as the PACNFirm object library, or by use of the CobraNet
Discovery program which are aware of the data structures and protocol utilized.
3.11 SNMP
Version 1 of the simple network management protocol (SNMP) is defined in RFC 1157.
The CobraNet SNMP interface is version 1 compliant.
A management information base (MIB) is associated with any SNMP implementation.
CobraNet supports the standard MIB for network devices as defined in RFC 1213 “MIB-II”
in addition to its own MIB for CobraNet-specific objects.
The CobraNet MIB file is available for public download in order to facilitate full use of the
CobraNet SNMP interface via SNMPv1 compliant applications.