Brocade TurboIron 24X Series Configuration Guide - Manual (Page 801)

Brocade TurboIron 24X Series Configuration Guide 767
53-1003053-01
Chapter
25
Configuring IP Multicast Traffic Reduction
In this chapter
• IGMP snooping overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 767
• PIM SM traffic snooping overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 771
• Configuring IGMP snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 773
• Configuring PIM SM snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 781
• IGMP snooping show commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 782
• PIM SM snooping show commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 788
• Clear commands for IGMP snooping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 790
IGMP snooping overview
When a device processes a multicast packet, by default, it broadcasts the packets to all ports
except the incoming port of a VLAN. Packets are flooded by hardware without going to the CPU. This
behavior causes some clients to receive unwanted traffic.
IGMP snooping provides multicast containment by forwarding traffic to only the ports that have
IGMP receivers for a specific multicast group (destination address). A device maintains the IGMP
group membership information by processing the IGMP reports and leave messages, so traffic can
be forwarded to ports receiving IGMP reports.
An IPv4 multicast address is a destination address in the range of 224.0.0.0 to 239.255.255.255.
Addresses of 224.0.0.X are reserved. Because packets destined for these addresses may require
VLAN flooding, devices do not snoop in the reserved range. Data packets destined to addresses in
the reserved range are flooded to the entire VLAN by hardware, and mirrored to the CPU. Multicast
data packets destined for the non-reserved range of addresses are snooped. A client must send
IGMP reports in order to receive traffic. If an application outside the reserved range requires VLAN
flooding, the user must configure a static group that applies to the entire VLAN.
An IGMP device's responsibility is to broadcast general queries periodically, and to send group
queries when receiving a leave message, to confirm that none of the clients on the port still want
specific traffic before removing the traffic from the port. IGMP V2 lets clients specify what group
(destination address) will receive the traffic but not to specify the source of the traffic. IGMP V3 is
for source-specific multicast traffic, adding the capability for clients to INCLUDE or EXCLUDE
specific traffic sources. An IGMP V3 device port state could be INCLUDE or EXCLUDE, and there are
different types of group records for client reports.
The interfaces respond to general or group queries by sending a membership report that contains
one or more of the following records associated with a specific group:
• Current-state record that indicates from which sources the interface wants to receive and not
receive traffic. This record contains the source address of interfaces and whether or not traffic
will be included (IS_IN) or not excluded (IS_EX) from this source.