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8.1.3.
Multicast Protocol Roles
Hosts must have a way to identify their interest in joining any particular multicast group, and routers must
have a way to collect and maintain group memberships. These functions are handled by the IGMP protocol
in IPv4. In IPv6, multicast routers use the Multicast Listener Discover (MLD) protocol to maintain group
membership information.
Multicast routers must also be able to construct a multicast distribution tree that enables forwarding
multicast datagrams only on the links that are required to reach a destination group member. Protocols such
as PIM handles this function.
IGMP and MLD are multicast group discovery protocols that are used between the clients and the local
multicast router. PIM-SM, and PIM-DM are multicast routing protocols that are used across different
subnets, usually between the local multicast router and remote multicast router.
8.1.4.
Multicast Switch Requirements
You use the IPv4/IPv6 multicast feature on the switch 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 “IGMP Snooping”. 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”.
If the switch is configured as a L3 switch and handles inter-VLAN routing through static routes or OSPF and
multicast traffic is transmitted within the network, enabling and configuring L3 multicast routing on the
switch is recommended.
8.1.5.
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 and PIM-SM are multicast routing protocols that help
determine the best route for IP (PIM) and IPv6 (PIM) multicast traffic.
8.1.6.
Multicast Routing Tables
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.
8.1.7.
Multicast Tunneling
If Multicast traffic is to be routed through a part of a network that does not support multicasting (routers
which are not multicast capable) then the multicast packets are encapsulated in an IP datagram and sent as a
unicast packet. When the multicast router at the remote end of the tunnel receives the packet, the router
Summary of Contents for QuantaMesh QNOS5
Page 1: ...QuantaMesh Ethernet Switch Configuration Guide QNOS5 NOS Platform ...
Page 209: ...209 Table 7 8 IPv6 Neighbor Discovery Settings ...
Page 226: ...226 Table 8 2 L3 Multicast Defaults ...
Page 254: ...254 Appendix A Term and Acronyms Table 9 5 Terms and Acronyms ...