Operation Manual – IGMP Snooping
Quidway S3100 Series Ethernet Switches
Chapter 1 IGMP Snooping Configuration
Huawei Technologies Proprietary
1-3
II. Layer 2 multicast with IGMP Snooping
The switch runs IGMP Snooping to listen to IGMP messages and map the hosts and
the ports that connect the hosts to the corresponding multicast group addresses.
Internet
Internet
IGMP-enabled router
IGMP message
IGMP message
IGMP Snooping-enabled
Ethernet switch
Figure 1-2
IGMP Snooping implementation
To implement Layer 2 multicast, the switch processes four different types of IGMP
messages it received, as shown in Table 1-3.
Table 1-3
IGMP Snooping messages
Mes
sage
Sen
der
Recei
ver
Purpo
se
Switch action
If yes, reset the aging
timer of the router port.
IGMP
gene
ra
l query
messa
ge
Multica
s
t rout
er
Multicast member
swit
ch
Query
if the
multica
st
groups
contain
any
memb
er
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
grou
p-spe
c
ific q
u
e
ry
messa
ge
Multica
s
t rout
er
Multicast member
swit
ch
Query
if a
specifi
c
multica
st
group
contain
s any
memb
er
Send a group-specific query message to the IP
multicast group being queried.