Reference Guide

Multicast Features

The Dell Networking OS supports the following multicast protocols:

● PIM Sparse-Mode (PIM-SM)

● Internet Group Management Protocol (IGMP)

● Multicast Source Discovery Protocol (MSDP)

Topics:

• Enabling IP Multicast

• Multicast with ECMP

• Implementation Information

• First Packet Forwarding for Lossless Multicast

• Multicast Policies

Enabling IP Multicast

Before enabling any multicast protocols, you must enable IP multicast routing.

● Enable multicast routing.

CONFIGURATION mode

ip multicast-routing

Multicast with ECMP

Dell Networking multicast uses equal-cost multi-path (ECMP) routing to load-balance multiple streams across equal cost links.

When creating the shared-tree protocol independent multicast (PIM) uses routes from all configured routing protocols to select

the best route to the rendezvous point (RP). If there are multiple, equal-cost paths, the PIM selects the route with the least

number of currently running multicast streams. If multiple routes have the same number of streams, PIM selects the first equal-

cost route the route table manager (RTM) returns.

In the following illustration, the receiver joins three groups. The last-hop DR initially has two equal-cost routes to the RP with no

streams, so it non-deterministically selects Route 1 for the Group 1 IGMP Join message. Route 1 then has one stream associated

with it, so the last-hop DR sends the Group 2 Join by Route 2. It then non-deterministically selects Route 2 for the Group 3 Join

because both routes already have one multicast stream.

512 Multicast Features