Dell POWEREDGE M1000E - Manual (Page 1152)

1152 Managing IPv4 and IPv6 Multicast
When Is L3 Multicast Required on the Switch?
You use the IPv4/IPv6 multicast feature on the PowerConnect M6220,
M6348, M8024, and M8024-k switches to route multicast traffic between
VLANs on the switch. If all hosts connected to the switch are on the same
subnet, there is no need to configure the IP/IPv6 multicast feature. If the
switch does not handle L3 routing, you can use IGMP snooping or MLD
snooping to manage port-based multicast group membership. For more
information, see "What Is IGMP Snooping?" on page 715 and "What Is MLD
Snooping?" on page 715. If the local network does not have a multicast router,
you can configure the switch to act as the IGMP querier. For more
information, see "IGMP Snooping Querier" on page 715.
If the switch is configured as a L3 switch and handles inter-VLAN routing
through static routes, OSPF, or RIP, and multicast traffic is transmitted
within the network, enabling and configuring L3 multicast routing on the
switch is recommended.
Determining Which Multicast Protocols to Enable
IGMP is recommended on any switch that participates in IPv4 multicasting.
MLD is recommended on any switch that participates in IPv6 multicasting.
PIM-DM, PIM-SM, and DVMRP are multicast routing protocols that help
determine the best route for IP (PIM and DVMRP) and IPv6 (PIM) multicast
traffic. For more information about when to use PIM-DM, see "Using PIM-
DM as the Multicast Routing Protocol" on page 1156. For more information
about when to use PIM-SM, see "Using PIM-SM as the Multicast Routing
Protocol" on page 1155. For more information about when to configure
DVMRP, see "Using DVMRP as the Multicast Routing Protocol" on
page 1158.
What Is the Multicast Routing Table?
Multicast capable/enabled routers forward multicast packets based on the
routes in the Multicast Routing Information Base (MRIB). These routes are
created in the MRIB during the process of building multicast distribution
trees by the Multicast Protocols running on the router. Different IP Multicast
routing protocols use different techniques to construct these multicast
distribution trees.