13
•
Facilitating the implementation of per-host accounting
Basic concepts in IGMP snooping
IGMP snooping related ports
As shown in
, Router A connects to the multicast source, IGMP snooping runs on Switch A
and Switch B, and Host A and Host C are receiver hosts—also called "multicast group members".
Figure 11 IGMP snooping related ports
IGMP snooping involves the following ports:
•
Router port—A router port is a port on a Layer 2 switch that leads toward a Layer 3 multicast
device—DR or IGMP querier. In
, GigabitEthernet 1/0/1 of Switch A and
GigabitEthernet 1/0/1 of Switch B are router ports. Each switch registers all its local router ports
in its router port list.
•
Member port—A member port is a port on a Layer 2 switch that leads toward multicast group
members. In
, GigabitEthernet 1/0/2 and GigabitEthernet 1/0/3 of Switch A and
GigabitEthernet 1/0/2 of Switch B are member ports. Each switch registers all the member ports
on the local device in its IGMP snooping forwarding table.
NOTE:
•
Whenever mentioned in this document, a router port is a port on the switch that leads the switch
to a Layer 3 multicast device, rather than a port on a router.
•
Unless otherwise specified, router/member ports mentioned in this document include static and
dynamic ports.
•
An IGMP-snooping-enabled switch deems that all its ports on which IGMP general queries with
the source IP address other than 0.0.0.0 or PIM hello messages are received are dynamic router
ports.
Aging timers for dynamic ports in IGMP snooping and related messages and actions
Table 6 Aging timers for dynamic ports in IGMP snooping and related messages and actions
Timer Description
Message before
expiry
Action after expiry
Dynamic router port
For each dynamic router
IGMP general query of
The switch removes this