Mixing Widths and Rates

InfiniBand cable width (lane count) can change from hop to hop, permitting lower-cost implementations to coexist with higher-performance ones. Similarly, InfiniBand switches perform speed matching between ports running at different lane rates. Per-hop rate and width-matching are automatically negotiated between switch pairs, enabling interoperability between InfiniBand generations. Auto-negotiation can also maintain fabric continuity by connecting at a lower rate or width if cable signal integrity is degraded. For example, a damaged HDR cable may still be capable of 100 Gbps (EDR), or of running one lane at 2.5 Gbps (1X SDR).Bit Error Rate (BER)

In a lossless network running at high data rates, InfiniBand cables must have excellent signal integrity and a low BER. The InfiniBand specification requires less than one-bit error per 10^12 bits transmitted. NVIDIA cables for both InfiniBand and Ethernet are individually factory tested to less than one-bit error per 10^15—1,000 times better.