System-level Configuration
NetXtreme-E User’s Manual
February 26, 2018 • NetXtreme-E-UG100
Page 47
Media Auto Detect
Since parallel detection is not supported in SerDes, the firmware has implemented a method to enhance link
detection called
Media Auto Detect
. This feature is controlled by CCM/HII as shown in
When
Media Auto Detect
is enabled, the link policy follows the state machine (see
) to establish a link
with a link partner. This behavior is dependent on the media type. For DAC cables, the method falls back to
different force modes and stops when there is a link-up.
NOTE:
Parallel detection is not supported when auto-negotiating at 25G or 10GbE. This means that if one
side is auto-negotiating and the other side is not, the link will not come up.
Figure 13: State Machine for the Media Auto Detect Feature
Table 28: Link Training Relationship Between Media Type and Speed
Local and Media Cable Type
Link Partner Link Training Setting
Force Speed Link
Training Disabled
Force Speed Link
Training Enabled
AN (Auto-Link Training)
Force Speed DAC (SFP+/SFP28/
QSFP28)
Link without Link
Training
Link with Link Training
Link with Link Training
Force Speed optical (Transceiver/AOC)
Link without Link
Training
Link without Link Training N/A
AN DAC (SFP+SFP28/QSFP28)
No Link
No Link
Link with Link Training
SFP+ with optical: 10G Forced
SFP28 with optical: 25G Forced
SFP28 with DAC: AN => 25G Forced => 10G Forced
AN
25G
Forced
10G
Forced
Failed
