Which feature is used in multicast routing to prevent loops?

The correct answer is C. RPF. RPF (Reverse Path Forwarding) is the core mechanism used in multicast routing to prevent loops. When a multicast packet arrives at a router, the router performs an RPF check: it looks up the source address of the packet and verifies that the packet arrived on the interface that…

Multicast Routing

Question

Options

ASTP
Binverse ARP
CRPF
Dsplit horizon

How the community answered

(31 responses)

A
3% (1)
B
3% (1)
C
87% (27)
D
6% (2)

Explanation

RPF (Reverse Path Forwarding) is the core mechanism used in multicast routing to prevent loops. When a multicast packet arrives at a router, the router performs an RPF check: it looks up the source address of the packet and verifies that the packet arrived on the interface that the router would use to reach that source (the RPF interface). If the check passes, the packet is forwarded; if it fails, the packet is discarded. This ensures multicast traffic flows away from the source in a loop-free tree. Option A (STP) prevents Layer 2 Ethernet loops, not multicast routing loops. Option B (Inverse ARP) resolves IP-to-Layer2 mappings. Option D (split horizon) prevents routing loops in distance-vector unicast protocols like RIP.

Topics

#multicast routing#RPF#loop prevention

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