HPE7-A12 Exam Dumps - HPE Networking Questions and Answers

In classical Protocol Independent Multicast - Sparse Mode (PIM-SM) deployments, a single router on a shared multi-access segment is elected as the Designated Router (DR) based on priority or highest IP address. Under standard PIM-SM, only this active DR joins the multicast shared distribution tree and forwards multicast traffic onto the segment, while the non-DR remains idle. In high-availability environments, if the active DR fails, multicast forwarding halts until neighbor hold timers expire, a new DR is elected, and new PIM Join messages build the distribution tree.

To overcome this failover penalty in mission-critical environments, ArubaOS-CX introduces PIM-SM Active-Active with Virtual Switching Extension (VSX). When configured across a VSX core/aggregation pair, both peer switches synchronize IGMP snooping tables, multicast routes, and outgoing interface lists (OIL) across the VSX Inter-Switch Link (ISL).

One VSX node operates as the active Designated Router, while the peer operates as a proxy Designated Router with its forwarding state fully staged in hardware. Should the active DR encounter an uplink failure or chassis outage, the peer proxy DR assumes active stream forwarding instantaneously, minimizing packet loss and preserving application delivery for mission-critical video, financial telemetry, or medical imaging feeds.

Reference Topics: HPE ArubaOS-CX High Availability – VSX Multicast Enhancements; PIM-SM Active-Active Synchronization and Sub-Second Recovery.

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