84
4.7
Multicast
Filtering
For
multicast
filtering,
the
switch
uses
IGMP
Snooping
technology.
IGMP
(Internet
Group
Management
Protocol)
is
an
Internet
Protocol
that
provides
a
way
for
internet
device
to
report
its
multicast
group
membership
to
adjacent
routers.
Multicasting
allows
one
computer
on
the
internet
to
send
data
to
a
multitude
of
other
computers
that
have
identified
themselves
as
being
interested
in
receiving
the
originating
computers
data.
Multicasting
is
useful
for
such
applications
as
updating
the
address
books
of
mobile
computer
users
in
the
field,
sending
out
newsletters
to
a
distribution
list,
and
broadcasting
streaming
media
to
an
audience
that
has
tuned
into
the
event
by
setting
up
multicast
group
membership.
In
effect,
IGMP
Snooping
manages
multicast
traffic
by
making
use
of
switches,
routers,
and
hosts
that
support
IGMP.
Enabling
IGMP
Snooping
allows
the
ports
to
detect
IGMP
queries,
report
packets,
and
manage
multicast
traffic
through
the
switch.
IGMP
has
three
fundamental
types
of
messages,
as
shown
below:
Message
Description
Query
A
message
sent
from
the
querier
(an
IGMP
router
or
a
switch)
which
asks
for
a
response
from
each
host
that
belongs
to
the
multicast
group.
Report
A
message
sent
by
a
host
to
the
querier
to
indicate
that
the
host
wants
to
be
or
is
a
member
of
a
given
group
indicated
in
the
report
message.
Leave
Group
A
message
sent
by
a
host
to
the
querier
to
indicate
that
the
host
has
quit
as
a
member
of
a
specific
multicast
group.
You
can
enable
IGMP
Snooping
and
IGMP
Query
functions
here.
You
will
see
the
information
of
the
IGMP
Snooping
function
in
this
section,
including
different
multicast
groups’
VID
and
member
ports,
and
IP
multicast
addresses
that
range
from
224.0.0.0
to
239.255.255.255.
In
this
section,
Force
filtering
can
determined
whether
the
switch
flooding
unknown
multicast
or
not.
Following
commands
are
included
in
this
group:
4.7.1
IGMP
Snooping
4.7.2
IGMP
Query
4.7.3
Force
Filtering
4.7.4
CLI
Commands
of
the
Multicast
Filtering
