3Com Switch 8800 Advanced Software V5 Configuration Guide

IGMP Snooping Configuration Task List 543
exist under the port: the switch deletes the forwarding entry corresponding to
the port from the forwarding table when the aging timer expires.
Processing of Multicast
Protocol Messages
Under different conditions, an IGMP Snooping-capable switch processes multicast
protocol messages differently, specifically as follows:
1 If only IGMP is enabled, or both IGMP and PIM are enabled on the switch, the
switch handles multicast protocol messages in the normal way.
2 In only PIM is enabled on the switch:
■ The switch broadcasts IGMP messages as unknown messages in the VLAN.
■ Upon receiving a PIM hello message, the switch will maintain the
corresponding router port.
3 When IGMP is disabled on the switch, or when IGMP forwarding entries are
cleared (by using the reset igmp group command):
■ If PIM is disabled, the switch clears all its Layer 2 multicast entries and router
ports.
■ If PIM is enabled, the switch clears only its Layer 2 multicast entries without
deleting its router ports.
4 When PIM is disabled on the switch:
■ If IGMP is disabled, the switch clears all its router ports.
■ If IGMP is enabled, the switch maintains all its Layer 2 multicast entries and
router ports.
IGMP Snooping
Configuration Task
List
Complete these tasks to configure IGMP Snooping:
Task Remarks
“Configuring Basic Functions of
IGMP Snooping” on page 544
“Enabling IGMP Snooping”
on page 544
Required
“Configuring the Version
of IGMP Snooping” on
page 545
Optional
“Configuring the Function
of Dropping Unknown
Multicast Data” on page
545
Optional
“Configuring IGMP Snooping Port
Functions” on page 546
“Configuring Static Ports”
on page 546
Optional
“Configuring Simulated
Joining” on page 547
Optional
“Enabling the Fast Leave
Feature” on page 548
Optional
“Configuring Port Aging
Timers” on page 549
Optional