What is mld – Dell POWEREDGE M1000E User Manual

Page 1154

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Managing IPv4 and IPv6 Multicast

The IGMP proxy offers a mechanism for multicast forwarding based only on

IGMP membership information. The router must decide about forwarding

packets on each of its interfaces based on the IGMP membership

information. The proxy creates the forwarding entries based on the

membership information and adds it to the multicast forwarding cache

(MFC) in order not to make the forwarding decision for subsequent multicast

packets with same combination of source and group.

What Is MLD?

Multicast Listener Discovery (MLD) protocol enables IPv6 routers to

discover the presence of multicast listeners, the hosts that wish to receive the

multicast data packets, on its directly-attached interfaces. The protocol

specifically discovers which multicast addresses are of interest to its

neighboring nodes and provides this information to the active multicast

routing protocol that makes decisions on the flow of multicast data packets.
The Multicast router sends General Queries periodically to request multicast

address listeners information from systems on an attached network. These

queries are used to build and refresh the multicast address listener state on

attached networks. Multicast listeners respond to these queries by reporting

their multicast addresses listener state and their desired set of sources with

Current-State Multicast address Records in the MLD2 Membership Reports.

The Multicast router also processes unsolicited Filter-Mode-Change records

and Source-List-Change Records from systems that want to indicate interest

in receiving or not receiving traffic from particular sources.
The PowerConnect implementation of MLD v2 supports the multicast router

portion of the protocol (i.e., not the listener portion). It is backward-

compatible with MLD v1.

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