Recommended Configurations for Access (Leaf) Switches
Table 2-3 lists the recommended function configurations and application scenarios, which are available only to the recommended device models.
Parameters on switches need to be set based on the corresponding parameter settings of server NICs. The same parameters must have consistent settings on both switches and server NICs.
Function |
Recommendation Level |
Application Scenario |
|---|---|---|
PFC |
Mandatory |
For the priority corresponding to RoCEv2 traffic, PFC needs to be enabled on each panel port based on the priority. The queue corresponding to the priority for which PFC is enabled is a lossless queue, which ensures that packets are forwarded without packet loss. |
PFC deadlock detection |
Mandatory |
After configuring PFC, you need to configure PFC deadlock detection to monitor PFC deadlocks. |
PFC deadlock prevention |
Optional |
PFC deadlock prevention preemptively avoids PFC deadlocks for typical DCNs of the Clos architecture. This function enables devices to identify service flows that may cause PFC deadlocks and modify the queue priority to prevent PFC deadlocks. This function is recommended for the distributed storage scenario. |
Low-latency network |
Recommended |
After the low-latency network function is enabled, the Virtual Input Queue (VIQ) (also called automatic buffer optimization) and dynamic ECN functions are enabled by default. VIQ can properly divide the buffer space at the chip or queue level, which helps implement lossless forwarding of packets in lossless queues. If the device does not support the AI ECN function, you can configure the dynamic ECN function to dynamically adjust the ECN threshold. |
Optimizing the buffer and PFC parameters |
Recommended |
Generally, the VIQ function can meet service requirements in the network. If the device does not support the VIQ and the service performance does not meet requirements or even packet loss occurs, you can manually adjust the buffer and PFC thresholds using commands. |
AI ECN |
Recommended (AI ECN, dynamic ECN, or static ECN must be configured.) |
After the AI ECN function is configured, the ECN threshold can be intelligently adjusted to achieve low latency and high throughput without packet loss. If dynamic ECN has been configured, disable it first. |
Static ECN |
Optional |
If the device does not support AI ECN and dynamic ECN, you can configure the static ECN function and set the ECN threshold for a specified queue. |
Fast ECN |
Recommended |
Fast ECN can be used to speed up ECN marking. This function is supported after the device is started and cannot be enabled or disabled using commands. |
ECN overlay |
Optional |
To use the ECN function on a VXLAN network, you must configure the ECN overlay function. |
Fast CNP |
Optional |
After the ECN function is configured, you can configure the fast CNP function to shorten the CNP feedback path and the time for the source end to decrease the sending rate. In the distributed storage scenario, congestion is more likely to occur if network convergence occurs and there is concurrent or burst traffic. To prevent such congestion, you are advised to enable the fast CNP function. |