individual NIC team MAC's showing up in ARP table - can it cause issues?

[anthonyhcs]

I have some physical servers using the Broadcom utility  to team the NIC's.  These teams have 2 members.  The software selects one of the members' MAC addresses to serve as the MAC for the team, and this is the MAC used by the OS (Windows in this case) as well.

For simplicity we'll call the MAC from NIC_1 "1E" and the MAC from NIC_2 "1F", and "1E" is the MAC for the team.  On the router the ARP table will at times have an entry for this server's IP address as "1E" and when the entry expires sometimes it will come up as "1F".  We are experiencing intermittent connectivity issues with these servers.  Can this issue be caused by router having "1F" in the table, but the server host only accepting "1E", but not "1F"?

Any other ideas/suggestions?

[Joseph Nelson]

Hi Anthony,

The issue is likely with the NIC teaming software. You have to ask yourself, why is the server using the member NIC "1F" to in ARP-Reply. It seems as if the server is failing over between the NICs.

Depending on your setup, your NIC teaming software may be using "L2 heartbeats" to detect link failure. It may be the case that your switches are intermittently droping those heartbeats--leading the server to failover. A packet capture could reveal this behavior as the server may gratuitous ARP with the new MAC when it detects failure.

HTH