
Industrial Managed
Ethernet Switch
User Manual
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Figure 2.92 Example of Static IP Multicast Setting
2.10.5 MLD
Multicast Listener Discovery (MLD) is a protocol used by EH75XX in Internet Protocol Version 6 (IPv6) network to
discover nodes on its directly attached interfaces that would like to receive multicast packets. These neighboring
nodes are called multicast listenters.MLD is embedded in ICMPv6 (Internet Control Message Protocol Version 6)
as a part of IPv6 protocol suit. It is similar to Internet Group Management Protocol (IGMP) in IPv4 as described in
Section 2.10. The protocol speficifically discovers which multicast addresses are of interest to its neighboring nodes.
For IPv6, the address range of FF00::/8 are reserved for multicast addresses. Then, MLD provides this information
to the active multicast routing protocol on the EH75XX so that multicast packets can be delivered to all relevant
interfaces and eventually to the subscribed multicast listeners. Note that MLD is an asymmetric protocol in which it
specifies different behaviours for multicast liteners and for routers (or managed switches in our case). The
MLD
section, which is under the
IP Multicast
menu, contains three submenus which are
Setting
,
IPv6 Multicast Table
,
and
Statistics
as shown in Figure 2.93.
Figure 2.93 MLD Submenus
Typically, MLD device can be classified as one of the follows: a querier, a snooper, or a proxy. An MLD querier is
a device that coordinate multicast streams and MLD membership information. The MLD querier can generate
membership query message to check which nodes are group members. It can process membership reports and
leave messages. An MLD snooper is a device that spies on MLD messages to create flow efficiencies by allowing
only subscribed interfaces to receive multicast packets. The MLD snooper can decide on the best path to send
multicast packets at Layer 2; however, it cannot alter those packets or generate its own MLD messages. An MLD
proxy is a device that passes membership reports upstream towards a source in anoter subnet. On the downstream,
the MLD proxy will forward multicast packets and queries towards one or more IP subnets.