Something "normal" for change. What's your experience on migrating an existing MPX to a VPX running on SDX? I ran in to some problems with HA failover migration the last time (suspecting the lack of VLAN tagging on the originating MPX, where as everything on SDX is tagged including the management interface). My plan is just to replicate the configuration on the VPXs (interfaces disabled) and do the actual failover just by disabling the interfaces on MPX and then enabling them on the SDX to avoid the huzzle we ran into the last time. My question is; in the internal network, we have critical sessions running that authenticate on the StoreFront and we are using HDX routing. Should these sessions stay alive if we can keep the time between the interface switch low? The sessions have STA tickets and that's the mechanism to identify the valid sessions after all? How reliable do you think this would be?

The method, if the only difference is VLAN tagging and/or interface numbering (which should be the case between and MPX and a VPX on SDX), is to disable push/pull replication in HA nodes on both netscaler so the VLAN tagging is independant and stay as configured on the two nodes (i.e tagged VLAN config on secondary VPX does not get replaced by the primary untagged MPX VLAN setting) then you should be able to failover while keeping sessions replicated.

how about INC configuration?

No INC, just the step I described (more or less not knowing what's in your setup in details).. used this to move Netscaler (HA pairs or standalone) from MPX, non SDX VPX or even SDX VPX to other form factors with different hardwares