Arista DCS-DS-7720R4-128PE-F | 7700R4 Distributed Spine Switch, 128x 800G OSFP

Q: What is the Arista 7700R4 Distributed Etherlink Switch architecture?
A: The 7700R4 DES is an ultra-scalable distributed system that operates as a single logical switch across multiple physical devices. It combines dedicated leaf and spine switches using a 2-tier topology to create a massively parallel fabric supporting over 4,600 x 800GbE hosts in a single configuration, with logical single-hop forwarding for predictable, lossless performance in AI/ML clusters.

Q: What workloads is the DCS-DS-7720R4-128PE-F designed for?
A: This spine switch is optimized for large-scale AI training and inference workloads, machine learning clusters, and HPC environments requiring RDMA over Converged Ethernet. It handles synchronized high-bandwidth collective communication operations like All-Reduce and All-to-All across thousands of GPU/XPU accelerators with deterministic, congestion-free performance.

Q: How does the 7720R4 spine switch integrate with leaf switches?
A: The 7720R4 spine connects exclusively to 7700R4 series leaf switches via its 128 x 800G OSFP fabric ports. Spine switches do not connect to each other or external networks. The distributed architecture uses automated hardware-accelerated scheduling and deterministic traffic spraying across all leaf-spine interfaces to achieve 100% path utilization without manual tuning.

Q: What advanced features support AI cluster performance?
A: The switch implements Virtual Output Queues (VOQ) to eliminate head-of-line blocking, cell-based traffic spraying for optimal load balancing, distributed credit scheduling for fairness, and deep buffering to handle incast patterns. It supports DCQCN, PFC, ECN, and Cluster Load Balancing protocols essential for RDMA workloads, with forward compatibility for Ultra Ethernet standards.

Q: What is included in the -F bundle configuration?
A: The DCS-DS-7720R4-128PE-F bundle includes the 7720R4 chassis with 128 x 800G OSFP ports, Supervisor-EL module with 8c/16t CPU, 64GB RAM and 512GB NVMe storage, front-to-rear airflow fans, 4 x AC power supplies with 4 x SAF-D C20 power cords (3m length), and 4-post mounting hardware. The -F suffix indicates fixed front-to-rear airflow direction.