Administrator Guide

Multicast Features

Dell Networking OS supports multicast features.

The Dell Networking OS supports the following multicast protocols:

• PIM Sparse-Mode (PIM-SM)

• PIM Source-Specific Mode (PIM-SSM)

• Internet Group Management Protocol (IGMP)

• Multicast Source Discovery Protocol (MSDP)

Topics:

• Enabling IP Multicast

• Implementation Information

• First Packet Forwarding for Lossless Multicast

• Multicast Policies

• IPv4 Multicast Policies

Enabling IP Multicast

Prior to enabling any multicast protocols, you must enable multicast routing.

• Enable multicast routing.

CONFIGURATION mode

ip multicast-routing

Implementation Information

Because protocol control traffic in the Networking OS is redirected using the MAC address, and multicast

control traffic and multicast data traffic might map to the same MAC address, the Dell Networking OS might

forward data traffic with certain MAC addresses to the CPU in addition to control traffic.

As the upper 5 bits of an IP Multicast address are dropped in the translation, 32 different multicast group IDs

all map to the same Ethernet address. For example, 224.0.0.5 is a known IP address for open shortest path

first (OSPF) that maps to the multicast MAC address 01:00:5e:00:00:05. However, 225.0.0.5, 226.0.0.5, and so

on, map to the same multicast MAC address. The Layer 2 forwarding information base (FIB) alone cannot

differentiate multicast control traffic multicast data traffic with the same address, so if you use IP address

225.0.0.5 for data traffic, both the multicast data and OSPF control traffic match the same entry and are

forwarded to the CPU. Therefore, do not use well-known protocol multicast addresses for data transmission,

such as the following.

Multicast Features 620