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MAC Address of the NIC Is All 0s

Publication Date:  2019-04-23 Views:  44 Downloads:  0
Issue Description

A MAC address flapping alarm is generated when the connected switch is a CE6800. It is found that the MAC address sent from the server is all 0s.

Handling Process

1. Use the packet capture software to analyze packets. The MAC address, which is all 0s, is sent from the server NIC. The keywords are FCoE initialization Protocol and FIP VLAN.


2. Check the MAC address of the physical NIC.

Query the MAC address of the server. The physical MAC address is normal.

3. Check other suspected NICs.

Based on analysis, some MAC addresses of Microsoft ISATAP Adapter are all 0s. However, Microsoft ISATAP Adapter is a virtual NIC used to convert IPv6 addresses to IPv4 addresses on the OS. The NIC has not enabled the IPv6 function. Therefore, the fault is not caused by Microsoft ISATAP Adapter.

4. Compare servers with the same configuration.

Comparison of servers with the same configuration shows that MAC addresses, which are all 0s, are sent from DB servers using the 82599 10GE NIC and with NIC binding enabled. In addition, the performance optimization mode of the NIC is Storage Server, whereas that of other normal servers is Standard Server..

After reviewing of the NIC binding guide used by the customer, it is found that the guide is out-of-date and applies only to the IC. The guide does not contain description about performance optimization and therefore does not provide guidance on how to correctly set the performance optimization mode.

Further checking of the DB servers shows that performance optimization is not available when GE NIC binding is enabled.



Root Cause

Through confirmation with Intel, if the MAC address of an NIC is all 0s, it is probable that the performance optimization mode of the NIC has been set to Storage Server. In this case, you need to change it to Standard Server. The Storage Server mode is used for improved reliability. The purpose of setting MAC addresses to all 0s is to ensure that all packets are received. After optimization has been made for FCoE and iSCSI NICs, the outcome is consistent with the captured packets.

Reference:

Pay attention to the following line:

If Low Latency Interrupts option is enabled, system CPU utilization can increase.

Solution

If NIC binding has been enabled with the performance optimization mode set to Storage Server, the MAC address sent from an NIC may be all 0s.

Change the performance optimization mode from Storage Server to Standard Server.

Suggestions

1) Compare and analyze the same environment to determine which module is related to the fault and narrow down the scope.

2) Consult parts supplier for reference.

END