Media Auto Detect - Broadcom NetXreme-C User Manual

NetXtreme-E User's Manual
Table 28: Link Training Relationship Between Media Type and Speed
Local and Media Cable Type
Force Speed DAC (SFP+/SFP28/
QSFP28)
Force Speed optical (Transceiver/AOC) Link without Link
AN DAC (SFP+SFP28/QSFP28)

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
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
February 26, 2018 • NetXtreme-E-UG100
Force Speed Link
Training Disabled
Link without Link
Training
Training
No Link
SFP+ with optical: 10G Forced
SFP28 with optical: 25G Forced
SFP28 with DAC: AN => 25G Forced => 10G Forced
25G
AN
Forced
Failed
Link Partner Link Training Setting
Force Speed Link
Training Enabled
Link with Link Training
Link without Link Training N/A
No Link
10G
Forced
System-level Configuration
AN (Auto-Link Training)
Link with Link Training
Link with Link Training
Figure 13.
Figure 13) to establish a link
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