My company recently purchased some Dell R740's with 2 Dual Port 25G SFP28 NIC's (Broadcom 57414) and wants to hook them up to an Arista 25G switch. We have two types of SFP adapters from Arista: SFP-25G-SR and SFP-10G-SR. We were hoping to get the servers running at 25G, but none of the 25G transceivers we have will operate at 25G when plugged into the R740.
Arista states in this document that the SFP-25G-SR connectors are the same as SFP28
Also, to keep the most basic configuration, there is a single fiber line running to each server, and each connected interface has only the following command:
switchport mode trunk
These are the configurations I've tried:
Server <–> Switch
Working Connections:
SFP-25G-SR <–> SFP-10G-SR
SFP-10G-SR <–> SFP-10G-SR
Unsuccessful Connections:
SFP-10G-SR <–> SFP-25G-SR
SFP-25G-SR <–> SFP-25G-SR
Just to ensure the switch and SFP adapters were not faulty, I plugged two of the 25G switches together with the 25G SFP's mentioned above and a link was established.
Are there any ideas as to why they aren't working as intended?
Best Answer
Forgot to add an answer..
In the Dell BIOS, they had set the default link speed on the port to be 10G non-negotiable. Once that was changed, I had to set the Link FEC to the same standard on both the switch and the NIC. The two options available were Fire-Code and Reed Solomon. Both were tested before being put in to production but we ended up ultimately choosing Reed Solomon Link FEC