Hi there!
Based on what I’ve checked:
DT0 vs ST0 Lane Configurations
DT0 Version (PCIe Switch Mode):
Yes, exactly! The DT0 has its 48 PCIe lanes locked in as 16 lanes upstream (to your host) and 32 lanes downstream (through MCIO for expansion). Think of it as a PCIe “hub” that can connect multiple devices.
ST0 Version (Multi-Host Mode):
You got it right again! The ST0 uses all 48 lanes as upstream lanes, perfect for connecting multiple hosts to the same NIC.
Can You Change the Lane Direction?
Nope, this is set in stone. The lane direction is hardwired during manufacturing - you can’t reconfigure a DT0 to work like an ST0 or vice versa. It’s like having two different tools designed for different jobs.
PCIe 5.0 Bandwidth Considerations
On a PCIe 5.0 server:
DT0 Version: You’re capped at ~64 GB/s (x16 upstream), which definitely bottlenecks the NIC’s full potential
ST0 Version: This gives you the full bandwidth utilization, especially when paired with the auxiliary card
Bottom Line
If you’re after maximum bandwidth on PCIe 5.0, go with the ST0 version. The DT0 is great if you need PCIe expansion capabilities, but it’s not the choice for maxing out your bandwidth.
Thanks,
Ilan