Huawei SD-WAN provides all four technologies. Per-flow load balancing distributes separate application flows among multiple links that have the same priority and satisfy the required SLA. Per-packet load balancing can transmit packets from one flow across multiple eligible links, improving aggregate bandwidth utilization for large file transfers, backups, and replication.

Multi-fed and selective receiving duplicates critical traffic across different links. The receiving device selects valid packets, removes duplicates, and preserves packet order. Packet loss or failure on one path therefore does not interrupt the service, enabling zero-millisecond link switchover in applicable deployments.

A-FEC dynamically generates redundant packets and adjusts the redundancy ratio according to measured packet loss. The receiving device reconstructs lost packets, reducing video freezing and voice-quality deterioration. Huawei describes both adaptive FEC and multi-fed selective receiving as WAN-optimization mechanisms for key traffic.

Intelligent traffic steering selects links according to application identity, quality, bandwidth, priority, and load. Therefore, A, B, C, and D are all correct.

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