A__mic8 / A__digital8 User Guide
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14. Glossary
IGMP
Internet Group Management Protocol
A communications protocol used by adjacent switches/routers on a network to
establish Multicast group memberships.
IGMP Querying/Snooping is a technique used by network switches to control the
forwarding of Multicast data packets. A switch with IGMP Querying/Snooping will
forward Multicast data packets only to the ports that are members of the Multicast
group. Whereas, a switch without IGMP Querying/Snooping will broadcast Multicast
data to all of its output ports. As a result, the volume of Multicast traffic will be
significantly reduced if a network switch supports IGMP Querying/Snooping.
IP Address
Internet Protocol address.
All devices connected to a data network must have a unique IP address. In IPv4, a 32-
bit number is used and a typical address looks like this:
192.168.101.240
. In IPv6, a
128-bit number is used.
In IPv4, subnets are used to divide the IP address range. For example, a subnet mask
of
255.255.255.0
effectively filters the first three fields of the address. So, providing the
subnet masks match, a device with an IP address =
192.168.101.xxx
can
communicate with another device using an IP address =
192.168.101.xxx
(where
xxx
is a unique number between
1
and
254
) without any further configuration or routing. A
Class C IPv4 address range runs from
0
to
255
. However,
.0
is usually reserved for use
as a gateway and
.255
as a broadcast address (by network switches). Therefore, this
type of network supports 254 clients/nodes. If communication is required outside of
the broadcast domain - for example, to a device with an IP address =
192.168.
102
.xxx
-
then the data packets must be redirected using a network switch
with Layer 3 routing capability.
IPv4
Internet Protocol Version 4 - see IP Address.
IPv6
Internet Protocol Version 6 - see IP Address.
LAN
Local Area Network
A data network that interconnects devices within a small geographic area (e.g. a
home, school or office building). LANs differ from WANs (Wide Area Networks) in that
they do not require leased telecommunications lines (i.e. there is no need for an
external service provider).
Latency
The amount of time delay between an audio signal entering and emerging from a
system.
Layer 2/3
See Network Switch.
Multicast
In a multicast data network, data is copied and distributed by the network
switch/router. This means that packets sent from a single device can be received by
multiple nodes at the same time (i.e. one to many). This differs from a unicast data
network where data packets are addressed to a single receiving node (i.e. one to one).
Network Router
See Network Switch.
Network Switch
A device used in data networks to interconnect multiple nodes. A Layer 2 network
switch conforms to the OSI Layer 2 model, meaning that they can handle the physical
and data link layers (i.e. cabling and basic packet transmission). This differs from a
Layer 3 network router which also handles the network layer (i.e. it can redirect
network packets).
NIC
Network Interface Card
A computer interface that connects to external network devices.
Nova73
A stand alone routing matrix with networking capabilities; this is a large matrix related
to the mc
2
series of Lawo consoles.
