Installation guide

Network Infrastructure for EtherNet/IP™
D-2
Appendix D Glossary of Terms
Term Definition
IEEE 802.3
A function that uses the I/O messaging services of another (I/O
server) device to perform a task. It initiates a request for an I/O
message to the server module.
IGMP snooping
See implicit messaging.
implicit messaging A function that provides I/O messaging services to another (I/O
client) device. It responds to a request from the I/O client.
Internet Group Management Protocol (IGMP) A protocol that nodes use to keep local switches apprised of
their membership in multicast groups. When all nodes leave a
group, switches (and routers) no longer forward packets that
arrive for the group.
Layer 2 (data link layer or level) A reference to the data link layer communication (e.g., frame
formats) or data link layer connections derived from the OSI
Reference Model. For local area networks, Layer 2 refers to
physical frame format and addressing. Thus, for an EtherNet/IP
network, a Layer 2 address is an Ethernet address.
Layer 3 (network layer or level) A reference to the network layer communication derived from
the OSI Reference Model. For TCP/IP networks, Layer 3 refers
to IP and the IP packet format. Thus, a Layer 3 address is an IP
address.
link Collection of nodes with unique MAC IDs. Segments connected
by repeaters make up a link; links connected by routers make up
a network.
message client A function that uses the explicit messaging services of another
(Message Server) device to perform a task. It initiates an explicit
message request to the server device.
message router The object within a node that distributes messaging requests to
the appropriate application objects.
message server A function that provides explicit messaging services to another
(Message Client) device. It responds to an explicit message
request from the Message Client.
multicast A transmission method by which a packet is sent to a selected
subset of all possible recipients. A node can belong to one or
more multicast groups. Multicast transmission is supported by
Ethernet and IP protocols. Approximately half of the UDP
packets on EtherNet/IP are sent via multicast.
multicast connection A connection from one node to many. Multicast connections
allow a single producer to be received by many consumer nodes.
network A collection of one or more subnets where each node’s MAC ID
is unique on the network. The series of nodes are connected by
some type of communication medium. The connection paths
between any pair of nodes can include repeaters, routers and
gateways.
network address or node address An identification value assigned to each node on the CIP