QTech QSW-3900, User Manual, Page: 137 / 245

QTECH Software Configuration Manual
10-136
Table 2-3 IGMP Snooping messages
Message Sender Receiver Purpose Switch action
If yes, reset the aging
timer of the router port IGMP
general
query
message Multicast
router
and
multicast
switch Multicast
member
switch
and host Query if
the
multicast
groups
contain
any
member Check if the message comes from the
original router port
If not, notify the multicast
router that a member is
in a multicast group and
start the aging timer for
the router port
IGMP
group-speci
fic query
message Multicast
router
and
multicast
switch Multicast
member
switch
and host Query if a
specific
IGMP
multicast
group
contains
any
member Send an IGMP group-specific query message to the IP multicast
group being queried.
If yes, add the IP multicast group
address to the MAC multicast group
table.
If yes,
add the
port to the
IP
multicast
group.
If yes,
check if
the port
exists in
the MAC
multicast
group
If not, add the port to
the MAC multicast
group, reset the aging
timer of the port and
check if the
corresponding IP
multicast group exists.
If not,
create an
IP
multicast
group
and add
the port to
it.
If not :
Create a MAC multicast group and notify the
multicast router that a member is ready to join the
multicast group.
Add the port to the MAC multicast group and start
the aging timer of the port.
Add all ports in the VLAN owning this port to the
forward port list of the MAC multicast group.
IGMP host
report
message Host Multicast
router
and
multicast
switch Apply for
joining a
multicast
group, or
respond
to an
IGMP
query
message Check if the
IP multicast
group has a
corresponding
MAC
multicast
group
Add the port to the IP multicast group.
If no response is
received from the port
before the timer times
out, the switch will
check whether the
port corresponds to a
single MAC multicast
group.
If yes, remove the
corresponding MAC
multicast group and
IP multicast group
If no, remove only
those entries that
correspond to this
port in the MAC
multicast group, and
remove the
corresponding IP
multicast group
entries IGMP leave
message Host Multicast
router
and
multicast
switch Notify the
multicast
router
and
multicast
switch
that the
host is
leaving its
multicast
group. Multicast router and multicast switch send
IGMP group-specific query packet(s) to the
multicast group whose member host sends
leave packets to check if the multicast
group has any members and enable the
corresponding query timer.
If no response is
received from the
multicast group
before the timer times
out, notify the router
to remove this
multicast group node
from the multicast
tree