Users Guide

Table Of Contents
NOTE: Layer 3 (L3) PIM and IGMP multicast is not supported on the S3048-ON switch. IGMP and Multicast Listener
Discovery (MLD) snooping is supported on all switches.
Configure multicast routing
Configuring multicast routing is a two-step process that involves configuring multicast routing and enabling PIM sparse mode
(PIM-SM) on a Layer 3 (L3) interface. The following procedure describes how to configure multicast routing.
For more information about IGMP and PIM feature configurations, see Internet Group Management Protocol and Protocol
Independent Multicast.
NOTE:
Multicast flood restrict feature is enabled by default. To ensure that no traffic drops occur, Dell Technologies recommends
that you do one of the following:
Disable IGMP snooping on the VLAN between two PIM routers that do not have IGMP receivers on that VLAN.
Configure the interface between the PIM routers as static mrouter port.
1. Enable multicast routing for IPv4 networks.
OS10# configure terminal
OS10(config)# ip multicast-routing
2. Configure an IP address to a VLAN interface.
OS10(config)# interface vlan 2
OS10(conf-if-vl-2)# ip address 1.1.1.2/24
3. Enable PIM sparse mode on an L3 interface.
OS10(config)# interface vlan 2
OS10(conf-if-vl-2) ip pim sparse-mode
4. From CONFIGURATION mode, configure the rendezvous point (RP) IP address statically and specify the multicast group
address range. The RP IP address should be reachable across the PIM domain.
OS10(config)# ip pim rp-address 171.1.1.1 group-address 225.1.1.3/32
5. Configure the RP address and multicast group address on all nodes in your network.
Unknown multicast flood control
The unknown multicast flood control feature enables the system to forward unknown multicast packets only to a multicast
router (mrouter).
When you enable multicast snooping, OS10 forwards multicast frames, whose destination is already learned, to their intended
recipients. When the system receives multicast frames whose destination is not known, it floods the frames for all ports on
the specific VLAN. All hosts that receive these multicast frames must process them. With multicast flood control, the system
forwards unknown multicast frames only to the interface that leads to the mrouter. The mrouter can then forward the traffic to
the intended destinations.
For multicast flood control to work, you must enable both IGMP and MLD snooping on the system. By default, multicast flood
control, IGMP snooping, and MLD snooping are enabled.
NOTE: The Multicast flood control feature is not supported on the S4248FB-ON and S4248FBL-ON switches.
The following describes a scenario where a multicast frame is flooded on all ports of all switches. The switches and hosts in the
network need not receive these frames because they are not the intended destinations.
Multicast
825