3Com Switch 7750 Configuration Guide

Overview 429
Table 335 IGMP Snooping messages
Message Sender Receiver Purpose Action of the multicast member switch
IGMP
general
query
message
Multicas
t router
and
multicas
t 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 yes, reset the aging timer of
the 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-sp
ecific
query
message
Multicas
t router
and
multicas
t 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.
IGMP
host
report
message
Host Multicast
router
and
multicast
switch
Apply for
joining a
multicast
group, or
respond
to an
IGMP
query
message
Chec
k if
the IP
multi
cast
group
has a
corres
pondi
ng
MAC
multi
cast
group
If yes, check if
the port exists in
the MAC
multicast group
If yes, add the IP
multicast group address
to the MAC multicast
group table.
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 yes,
add
the
port to
the IP
multica
st
group.
If not,
create
an IP
multica
st
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 router ports in the VLAN
owning this port to the MAC multicast
group.
■ Create an IP multicast group and add
the port to it.