Symptom
Connectivity issues due to host MAC's not constantly refreshed on OTV ED's based on traffic flows.
Conditions
Upon Firewall or other L3 Gateway failover to other DC.
Workaround
Do not allow MAC's to timeout on OTV ED's. Either by ensuring some broadcast is sent from such hosts in the VLAN or disabling MAC aging on OTV ED's (MAC table then needs to be sanitized periodically to avoid hitting the limit)
Selective flood knob is available since 6.2:
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus7000/sw/otv/command/reference/nxos_otv_cr/basics_otv_cmds.html#pgfId-1236972
More Info
OTV by design does not allow flood and learn. If local MAC is not present on OTV Edge locally, traffic from other DC will never reach such hosts across Overlay.
This is an enhancement request to explore a possibility to have per VLAN flood option for Unknown Unicast to flow across Overlay.
