Forward error correction (FEC) is a technique used for controlling errors in data transmission at high speeds. With FEC, the destination recognizes only the data with no errors from the source that is sending redundant error correcting code with the data frame. This technique extends the range of the signal by correcting error without retransmission. FEC enhances data reliability.
Available FEC modes:
- CL91-RS - Supports 100 GbE
- CL108-RS – Supports 25 GbE and 50 GbE
- CL74-FC – Supports 25 GbE and 50 GbE
- Auto
- Off
In SmartFabric mode, configuring FEC is supported on OME-M 1.20.00 and later. FEC options CL91-RS, CL108-RS, CL74-FC, Auto, and Off are available. The options displayed in the UI vary depending on the speed of the selected interface.
The following table shows the default FEC and auto negotiation values for optics and cables for the QSFP28-DD and QSFP28 ports at 200 GbE and 100 GbE speeds.
Media | Auto negotiation | FEC |
200 GbE and 100 GbE DAC | Enabled | CL91-RS |
200 GbE and 100 GbE Fiber or AOC, except LR-related optics | Disabled | CL91-RS |
200 GbE and 100 GbE LR-related optics | Disabled | Disabled |
The following table shows the default FEC and auto negotiation values for optics and cables for the QSFP28-DD and QSFP28 ports at 200, 100, 50, and 25 GbE speeds.
Media | DAC cable type | Auto negotiation | FEC |
200, 100, 50, and 25 GbE DAC | CR-L | Enabled | CL-108-RS |
CR-S | Enabled | CL-74-FC | |
CR-N | Enabled | Disabled | |
200, 100, 50, and 25 GbE Fiber or AOC, except LR-related optics | N/A | Disabled | CL108-RS |
200, 100, 50, and 25 GbE LR-related optics | N/A | Disabled | Disabled |
To configure FEC in Full Switch mode, find the relevant version of the Dell SmartFabric OS10 User Guide in the OME-M and OS10 compatibility and documentation table.
To configure FEC in SmartFabric mode on the OME-M console, perform the following steps.
Steps
- Access the OME-M console.
- Choose Devices > I/O Modules > Click on an I/O Module.
- In an I/O Module option, choose Hardware > Port Information. This option lists the IOM ports and its information.
- Select a port to configure FEC and click Configure FEC option at the top. Note: FEC options are not supported for compute sled facing ports and FEM ports (breakout FEM, virtual ports).
- This shows the Current and Auto negotiated FEC Settings. Choose FEC Type for the port selected from the list.
Verify FEC configuration
FEC can be verified on I/O Module CLI in Full switch and SmartFabric mode. Run the following command to verify.
The show interface ethernet 1/1/41 command shows the current and negotiated FEC for port 1/1/41.
MX9116N-A1# show interface ethernet 1/1/41
Ethernet 1/1/41 is up, line protocol is up
Port is part of Port-channel 2
Hardware is Eth, address is 20:04:0f:21:d4:f1
Current address is 20:04:0f:21:d4:f1
Pluggable media present, QSFP28 type is QSFP28 100GBASE-SR4-NOF
Wavelength is 850
Receive power reading is not available
Interface index is 112
Internet address is not set
Mode of IPv4 Address Assignment: not set
Interface IPv6 oper status: Disabled
MTU 9216 bytes, IP MTU 9184 bytes
LineSpeed 100G, Auto-Negotiation off
Configured FEC is cl91-rs, Negotiated FEC is cl91-rs
(Output Truncated)