Link Layer Retry Validation in AI Ethernet Fabrics

The 2026 OCP Global Summit takes place from October 12 to 15, 2026, in San Jose, California, presenting hardware and network infrastructure innovations for high-density data centers. At Booth C83 in the San Jose Convention Center, Keysight Technologies, Inc. conducts multi-vendor interoperability demonstrations of Link Layer Retry (LLR) and Credit-Based Flow Control (CBFC) alongside Broadcom and Alibaba Cloud, targeting next-generation Ethernet-based AI scale-up architectures.

Core Technology and System Architecture
Link Layer Retry provides hardware-level frame retransmission at the link layer, mitigating transient packet loss without triggering upper-layer protocol backoff mechanisms. Running across both 200G and 100G SerDes implementations, LLR establishes link resiliency and frame recovery essential for synchronized AI training clusters. In combination with CBFC at 100G SerDes, which prevents receiver buffer exhaustion through credit exchanges, the transport mechanisms maintain lossless behavior across high-throughput distributed compute fabrics.

Deployment or Implementation
Testing scenarios evaluate physical and link-layer integration across distinct hardware ecosystems. A 1.6T deployment couples the Keysight INPT-1600GE test platform with a Broadcom Tomahawk 6 (TH6) switch ASIC over eight lanes of 200G SerDes. Concurrently, a 400GE deployment connects Keysight test instrumentation to an Alibaba Cloud scale-up Ethernet switch utilizing Broadcom Tomahawk Ultra silicon over 100G SerDes channels. The testbeds measure LLR frame recovery, link resiliency, and protocol conformance under full-bandwidth transmission loads.

Industry Applications
Hyperscale operators, ASIC fabricators, switch original equipment manufacturers, and AI accelerator system designers require deterministic transport across scale-up topologies. Large-scale transformer training clusters depend on ultra-low latency and zero packet discard across inter-accelerator communication links. Applying LLR and CBFC to Ethernet environments enables data center operators to leverage standard Ethernet economics and multi-vendor supply chains while matching the strict lossless performance requirements traditionally reserved for proprietary fabric technologies.

Operational Impact and Performance Metrics
Validating LLR over 200G SerDes and CBFC over 100G SerDes confirms cross-vendor protocol state machine compatibility across discrete physical layer implementations. Standardizing these layer-2 mechanisms removes proprietary lock-in and eliminates packet drop anomalies that disrupt collective AI communication routines. Automated conformance and interoperability test suites accelerate pre-deployment hardware verification cycles, providing repeatable validation criteria before commissioning multi-terabit Ethernet clusters in production facilities.

Edited by Romila DSilva, Induportals Editor, with AI assistance.