Reference Guide

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Multicast Features
The Dell Networking operating system (OS) supports the following multicast protocols.
• PIM Sparse-Mode (PIM-SM)
• Internet Group Management Protocol (IGMP)
• Multicast Source Discovery Protocol (MSDP)
Enabling IP Multicast
Enabling IP Multicast is supported on the S5000 switch.
Prior to enabling any multicast protocols, you must enable 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.
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Multicast Features