VSX failure scenarios

Failure scenarios	Result with split recovery off	Result with split recovery on (default)
VTEP uplink failure	No impact to logical VTEP. Loopback connectivity between VTEPs will reroute through other available links using OSPF/BGP.	No impact to logical VTEP. Loopback connectivity between VTEPs will reroute through other available links using OSPF/BGP.
VTEP downlink failure	No impact to logical VTEP. Only VSX LAG to server is impacted.	No impact to logical VTEP. Only VSX LAG to server is impacted.
a) VSX Keepalive down. ISL up. b) Then after sometime, ISL goes down.	No impact to logical VTEP (but loss of split detection). No impact to logical VTEP (but loss of split detection and ISL sync).	No impact to logical VTEP (but loss of split detection). No impact to logical VTEP (but loss of split detection and ISL sync). NOTE: Without ISL ARP sync, in routing scenarios, this split condition may lead to traffic loss where ARP request originated from a VSX device and reply lands on the peer VSX device.
a) ISL down, VSX Keepalive up.	Secondary VSX node tears down VSX LAG member ports and brings down logical VTEP to ensure that VXLAN traffic is only sent to the primary VSX switch.	Secondary VSX node tears down VSX LAG member ports and brings down logical VTEP to ensure VXLAN traffic is only sent to the primary VSX switch.
a) ISL down, VSX Keepalive up. b) Then, after sometime, VSX Keepalive down as well.	Secondary VSX node tears down VSX LAG member ports and brings down logical VTEP to ensure VXLAN traffic is only sent to the primary VSX switch. Secondary VSX LAGs and logical VTEP stay down.	Secondary VSX node tears down VSX LAG member ports and brings down logical VTEP to ensure that VXLAN traffic is only sent to the primary VSX switch. Secondary VSX node restores VSX LAG member ports and brings up logical VTEP. NOTE: Without ISL ARP sync, in routing scenarios, this split condition may lead to traffic loss where ARP request originated from a VSX device and reply lands on the peer VSX device.
a) ISL and keepalive are down b) Keepalive restore	Secondary VSX node tears down VSX LAG member ports and brings down logical VTEP(If it was UP earlier) to ensure that VXLAN traffic is only sent to primary VSX switch.	Secondary VSX node tears down VSX LAG member ports and brings down logical VTEP to ensure that VXLAN traffic is only sent to primary VSX switch.

For more details on VSX failure scenarios, see Troubleshooting in the Virtual Switching Extension (VSX) Guide.