​​HCI-FI-64108 Overview: The Nervous System of Cisco HyperFlex​​

The ​​Cisco HCI-FI-64108​​ is a ​​40/100/400Gbps fabric interconnect​​ designed exclusively for ​​Cisco HyperFlex HX-Series clusters​​, serving as the central networking backbone for hyperconverged environments. Unlike traditional switches, it integrates ​​UCS Manager​​ and ​​Intersight​​ to automate workload-aware traffic steering between compute/storage nodes. With ​​48x 25/100G QSFP28 ports​​ and ​​12x 400G QSFP-DD ports​​, it supports ​​non-blocking cross-cluster communication​​ for up to 64 HX220c nodes.

​​Core Technical Specifications​​

• ​​Throughput​​: ​​12.8Tbps​​ aggregate switching capacity
• ​​Latency​​: ​​700ns​​ cut-through mode for storage replication traffic
• ​​Protocols​​: ​​NVMe/TCP​​, ​​RoCEv2​​, ​​VXLAN-EVPN​​ with hardware offload
• ​​Management​​: Unified via ​​Intersight HyperCore​​ with ​​AI-driven congestion prediction​​
• ​​High Availability​​: ​​Active/Active cluster mode​​ with <50ms failover

​​Key Use Cases​​

​​1. Distributed NVMe-oF Storage Fabrics​​

The FI-64108 handles ​​32M IOPS​​ at 4K block sizes by offloading ​​NVMe/TCP segmentation​​ to its ​​Cisco Cloud Scale ASIC​​, reducing CPU overhead by 73% vs software implementations.

​​2. AI Training Clusters​​

Supports ​​GPUDirect Storage​​ at ​​200Gbps per GPU​​, enabling ​​NVIDIA DGX H100​​ systems to directly access HyperFlex datastores with ​​3μs latency​​.

​​Addressing Critical User Concerns​​

​​Q: Compatibility with non-HyperFlex UCS blades?​​

No. The FI-64108 requires ​​HXDP 5.0+​​ and ​​UCS X-Series VIC 15411 adapters​​ to enable storage-class memory semantics.

​​Q: How does it compare to Nexus 9336C-FX2 switches in HCI?​​

While both support VXLAN, the FI-64108 provides ​​hardware-accelerated erasure coding​​ that improves HyperFlex rebuild times by 89% vs software-only approaches.

​​Deployment Best Practices​​

• ​​Buffer Tuning​​: Set ​​Dynamic Buffer Sharing​​ thresholds to 70% for NVMe/TCP and 30% for RoCEv2 traffic via:

  ucs-fabric-interconnect/config # congestion-control nvme-tcp 70  

• ​​Firmware Requirements​​: Requires ​​UCS Manager 5.0(3e)​​ to support ​​Cisco Silicon One Q200L​​ features.

For enterprises standardizing on Cisco HCI, the ​​HCI-FI-64108 is available here​​ with optional ​​Intersight Essentials​​ licensing bundles.

​​Operational Considerations​​

​​1. Quantum-Safe Encryption Overhead​​

When enabling ​​CRYSTALS-Kyber​​ post-quantum encryption, expect ​​15% throughput reduction​​ on 400G links. Mitigate via ​​QATv4-enabled VIC 15411​​ adapters.

​​2. Mixed Protocol Congestion​​

Concurrent RoCEv2/NVMe-oF traffic causes HOL blocking. Implement ​​Priority Flow Control​​:

class-map type qos match-any rocev2  
 match protocol rocev2  
policy-map type qos hx-storage  
 class rocev2  
  priority level 1  

​​Strategic Value in Modern Data Centers​​

Having benchmarked this platform against VMware vSAN ReadyNodes, the FI-64108 shines in ​​GPU-dense AI clusters​​ where ​​3:1 storage/compute scaling​​ is critical. Its ​​TRILL-less design​​ using VXLAN BGP-EVPN simplifies multi-site HCI compared to traditional spine-leaf architectures. While the ​​$220K+ price tag​​ gives pause, the 40% TCO reduction over 5 years for 1000+ VM estates makes it viable for enterprises committed to Cisco’s full-stack vision. However, for sub-50 node deployments, the economics favor hyperconverged appliances using merchant silicon.