Rockwell Automation 1756-ENET/B ControlLogix Ethernet Communication Interface Module User Manual - Manual (Page 34)

Publication 1756-UM051B-EN-P - November 2000
3-2 Before You Configure Your Module
User Datagram Protocol (UDP)
UDP is a much simpler transport protocol. It is connectionless and
provides a very simple capability to send datagrams between two
devices. UDP is used by applications that implement their own
handshaking between devices and only want a minimal transport
service. UDP is smaller, simpler, and faster than TCP and can operate
in unicast, multicast, or broadcast mode. The 1756-ENET/B module
employs UDP for real time I/O messaging.
Ethernet/IP
Ethernet/IP applies a common application layer over Ethernet by
encapsulating messages in TCP/UDP/IP. This common application
layer is the control and information protocol (CIP, see chapter 1),
which provides interoperability and interchangeability of industrial
automation and control devices on Ethernet. Ethernet/IP supports
both real-time I/O (“implicit” messaging) and explicit messaging.
Refer to the Ethernet/IP Performance and Application Guide,
publication number ENET-AP001A-EN-P, for more information on the
Ethernet/IP protocol.
Simple Network Management Protocol (SNMP)
Simple Network Management Protocol (SNMP) is a standard for
network management within TCP/IP environments. This lets client
applications monitor and manage network information on host
computers and gateways.
SNMP uses a distributed architecture consisting of management
systems and agents. Data is passed from SNMP agents, which are
hardware and/or software processes reporting activity in each
network device (switch, router, bridge, etc.) to the workstation
console used to oversee the network. The agents return information
contained in a MIB (Management Information Base), which is a data
structure that defines what is obtainable from the device and what can
be controlled (turned off, on, etc.).
The ENET/B module is an agent, and its primary function is to process
the operations requested by the management system. The Ethernet
module supports the SNMP protocol at the MIB II level.