IJ29792: ROCE ADAPTER SENDING LLDP MULTICAST CAUSES NETWORK FAILURE

APAR status

• Closed as fixed if next.

Error description

• RoCE network adapter sends LLDP multicast packets.
  If an etherchannel is configured using this adapter
  without
  custom MAC address, network communication through this
  etherchannel stops working after an etherchannel failover
  to
  the backup adapter. The reason is that the primary
  adapter keeps sending LLDP multicast packet containing
  its
  MAC address while the backup adapter also uses this
  MAC address after failover and this confuses the network
  switch since it sees the same MAC address from two ports
  at the same time.
  

Local fix

• configure and enable a user defined MAC address for the
  Etherchannel device:
  
  # chdev -l entX -a alt_addr=0x...... -P
  # chdev -l entX -a use_alt_addr=yes -P
  -> Reboot to activate the change
  

Problem summary

• If etherchannel is configured in NIB Mode on top of Mellanox
  adapters, then during primary to backup port fail over time we
  may face poor network performance. This is because the failed
  primary port also send LLDP packets to the switch and hence the
  switch get confused on the port failure.
  

Problem conclusion

Temporary fix

Comments

• This APAR is being closed FIN. This means that a solution to
  this APAR is expected to be delivered from IBM in a release
  (if any) to be available within the next 24 months.
  

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IJ25573

• APAR is sysrouted TO one or more of the following:

Fix information

Applicable component levels