Dell Force10 S4820T S4820T Configuration Guide - Page 676

www.dell.com | support.dell.com Multicast with ECMP Dell Force10 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 returned by the Route Table Manager (RTM). In Figure 32-1, 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 since both routes already have one multicast stream. Figure 32-1. Multicast with ECMP Route 2 IGMP Join: G3 IGMP Join: G2 Source Gig B Gig X RP Gig Y IGMP Group Table Group Address Interface Group 1 GigabitEthernet Y Group 2 GigabitEthernet X Group 3 GigabitEthernet X Gig Z Gig W IGMP Join: G1 Gig A Receiver IGMP Group Table Group Address Interface Group 1 GigabitEthernet A Group 2 GigabitEthernet A Group 3 GigabitEthernet A Route 1 Implementation Information • Because protocol control traffic in FTOS is redirected using the MAC address, and multicast control traffic and multicast data traffic might map to the same MAC address, FTOS might forward data traffic with certain MAC addresses to the CPU in addition to control traffic. 676 | Multicast Features