Concept 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-Specic 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

• Understanding Multicast Traceroute (mtrace)

• Printing Multicast Traceroute (mtrace) Paths

• Supported Error Codes

• mtrace Scenarios

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 trac in the Networking OS is redirected using the MAC address, and multicast control trac and multicast data

trac might map to the same MAC address, the Dell Networking OS might forward data trac with certain MAC addresses to the CPU in

addition to control trac.

As the upper 5 bits of an IP Multicast address are dropped in the translation, 32 dierent 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 rst (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 dierentiate multicast control trac multicast data trac with the same address, so if you use IP address 225.0.0.5

for data trac, both the multicast data and OSPF control trac 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.

Protocol

Ethernet Address

OSPF

01:00:5e:00:00:05

548 Multicast Features