3Com SuperStack II 3300 User Manual page 154

154 G
LOSSARY
ICMP
IEEE
IGMP
IGMP querier
IGMP snooping
IP Address
IPv4
Layer 2
Internet Control Message Protocol (RFC 792) — ICMP allows hosts to
find the routers attached to their segments and provides certain
diagnostic capabilities to the hosts when the routers are unable to
deliver packets to addressed destinations.
Institute of Electrical and Electronics Engineers — committees that
develop and propose computer standards, such as the 802 protocols,
which define the physical and data link protocols of communication
networks. Members represent an international cross section of users,
vendors and engineering professionals.
Internet Group Management Protocol (RFC 1112) is used by IP hosts to
report their multicast group memberships to any adjacent multicast
routers. It lets all the systems on a physical network know which hosts
currently belong to which multicast groups.
The device on a network that sends out IGMP query requests, in order
to identify which hosts are members of multicast groups.
A Layer 2 switch uses IGMP snooping to identify which hosts have
requested multicasts. The switch can therefore identify which hosts
should receive a multicast stream, and also prevent the multicast stream
from going to those hosts that have not requested multicasts.
Internet Protocol address — a unique identifier for a device attached to
a network using TCP/IP. The address is written as four octets separated
with full-stops (periods), and is made up of a network part, identifying
what network the device resides on, and a host part, identifying
individual devices on a given network.
IPv4 (RFC 791) is a Layer 3 connectionless, datagram delivery service.
Information about the organization of IPv4 networks and how to pass
datagrams within those networks is controlled by the routing protocol.
IPv4 defines two distinct communications methods for end stations:
Unicast
A point-to-point method for communicating between two
end-stations.
Multicast
A point-to-multipoint method for communication from one
end-station to one or more end stations.
The datalink (or MAC) layer in the OSI 7-layer model.