Configuration Guide User guide

FastIron Configuration Guide 1611
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Chapter
37
MLD Snooping on FastIron X Series Switches
Table 273 lists the individual Brocade FastIron switches and the Multicast Listening Discovery
(MLD) snooping features they support. These features are supported in the Layer 2, base Layer 3,
and full Layer 3 software images.
MLD Snooping Overview
The default method a device uses to process an IPv6 multicast packet is to broadcast it to all ports
except the incoming port of a VLAN. Packets are flooded by hardware without going to the CPU,
which may result in some clients receiving unwanted traffic.
If a VLAN is not Multicast Listening Discovery (MLD) snooping-enabled, it floods IPv6 multicast data
and control packets to the entire VLAN in hardware. When snooping is enabled, MLD packets are
trapped to the CPU. Data packets are mirrored to the CPU and flooded to the entire VLAN. The CPU
then installs hardware resources so subsequent data packets can be hardware-switched to desired
ports without going through the CPU. If there is no client report, the hardware resource drops the
data stream.
MLD protocols provide a way for clients and a device to exchange messages, and allow the device
to build a database indicating which port wants what traffic. Since the MLD protocols do not specify
forwarding methods, MLD snooping or multicast protocols such as IPv6 PIM-Sparse Mode (PIM SM)
are required to handle packet forwarding. PIM SM can route multicast packets within and outside a
VLAN, while MLD snooping can switch packets only within a VLAN. FESX and FSX devices do not
support PIM-SM routing.
MLD snooping provides multicast containment by forwarding traffic only to those clients that have
MLD receivers for a specific multicast group (destination address). The device maintains the MLD
group membership information by processing MLD reports and generating messages so traffic can
be forwarded to ports receiving MLD reports. This is analogous to IGMP Snooping on Brocade Layer
3 switches.
TABLE 273 Supported MLD snooping features
Feature FESX
FSX 800
FSX 1600
FWS FCX ICX 6610 ICX 6430
ICX 6450
MLD V1/V2 snooping (global and local) Yes This chapter describes MLD snooping on the FESX, FSX
800 and FSX 1600. For information about MLD
snooping on other FastIron devices, see Chapter 38,
“MLD Snooping on FastIron WS and Brocade FCX and
ICX Switches”.
MLD fast leave for V1 Yes
MLD tracking and fast leave for V2 Yes
Static MLD and IGMP groups with support
for proxy
Yes