PowerEdge: C6520 C6620 - iDRAC9 Connectivity Lost to shared LOM After Server Powered Off
Summary: Dell C6520 and C6620 sleds lose iDRAC9 connectivity when powered off in shared mode if connected to a switchport not supporting 10/100Mb negotiation.
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Symptoms
- This is observed when the server is powered off.
- The issue is not seen when a reboot of the server is performed.
- Only if the server is powered on physically, then the connectivity to iDRAC is restored.
Cause
When iDRAC9 is in shared mode on LOM1 of C6520/C6620 sleds, it uses the Broadcom controller to share its physical port with the Host OS.
On the sleds, the Broadcom 5720 Network Interface Controller (NIC) enters a low power operation state when the compute sled is powered off.
In this low power state, the NIC reduces the negotiated link to a 10 Mb or 100 Mb speed.
If the iDRAC network is connected to a switchport that does not support a 10/100Mb negotiation, (example: GLC-T transceivers on 10/25Gb SFP+ switch ports), the iDRAC drops network connectivity when the server is powered off.
This low power mode behavior is only present when iDRAC is in shared mode on LOM1. iDRAC9 dedicated mode can negotiate 1 Gbps link speed when the server is in powered off state.
On the sleds, the Broadcom 5720 Network Interface Controller (NIC) enters a low power operation state when the compute sled is powered off.
In this low power state, the NIC reduces the negotiated link to a 10 Mb or 100 Mb speed.
If the iDRAC network is connected to a switchport that does not support a 10/100Mb negotiation, (example: GLC-T transceivers on 10/25Gb SFP+ switch ports), the iDRAC drops network connectivity when the server is powered off.
This low power mode behavior is only present when iDRAC is in shared mode on LOM1. iDRAC9 dedicated mode can negotiate 1 Gbps link speed when the server is in powered off state.
Resolution
This is Working as Designed. As a workaround, end users can do the below actions:
- Go to System Setup > select the Embedded NIC settings and change the Energy-Efficient Ethernet option to Disabled (from Maximum Power Savings) for the Broadcom 5720.
- Reboot the server.
- Change iDRAC NIC selection setting to Dedicated.
- F2 System Setup > iDRAC Settings > Network
- Set the NIC selection to Dedicated
- Reboot the server.
Affected Products
C Series, Remote Enterprise Systems Management, Broadcom NetXtreme Family of Adapters, PowerEdge C6520, PowerEdge C6620Article Properties
Article Number: 000215514
Article Type: Solution
Last Modified: 18 May 2026
Version: 5
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