iSCSI disconnections across all ESXi hosts

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms: 

• The ISCSI LUNs are getting disconnected periodically on ESXI hosts 
  
  
• /var/log/syslog.log shows "Kernel reported iSCSI connection 1:0 error"

2025-11-25T10:41:18.691Z Wa(28) iscsid[2098041]: Kernel reported iSCSI connection 1:0 error (1011) state (3)
2025-11-25T10:41:21.7112 Wa(28) iscsid[2098041]: connection 1:0 (iqn.2015-11.com. hpe:storage.msa####.########f8ca77 if=iscsi_vmk@vmk# addr=1#.##.##.##8:3260 (TPGT: 1 ISID: 0x1) (TO CO) ) has recovered (2 attempts) 

 

Environment

ESX  9.x
ESXi 8.x
ESXi 7.x

Cause

• The Hosts are losing the access to the storage because ##.##.##.118 has been configured for MAC 00:#0:ff:f9:##:a2 and ##:#0:ff:f9:#5:b2. It is an IP conflict. 
  
  
• Packet Capture clearly shows the MACs associated with the IP address. 

Frame 39303: 60 bytes on wire (480 bits), 60 bytes captured (480 bits)

Ethernet II, Src: SeagateCloud_##:##:a2 (##:##:##:##:##:a2), Dst: VMware_##:##:51 (##:##:##:##:##:51)

Address Resolution Protocol (reply)

[Duplicate IP address detected for ##.##.##.118 (##:##:##:##:##:a2) - also in use by ##:##:##:##:##:a2 (frame 39302)]

[Frame showing earlier use of IP address: 39302]

[Expert Info (Warning/Sequence): Duplicate IP address configured (##.##.##.118)]

[Duplicate IP address configured (##.##.##.118)]

[Severity level: Warning]

[Group: Sequence]

[Seconds since earlier frame seen: 0]

 

Resolution

Resolving the IP address conflict will successfully addressed the connectivity issue.

Additional Information

• Collecting packet Captures

1. Packet capture on ESXi using the pktcap-uw tool
2. Packet Captures in ESXi using tcpdump-uw