vCenter 2.5 U5 / ESX 3.5 U4 - vSwitch/PortGroup - VST - inbound/outbound OK except for the Netbackup Media Server
All vms on dedicated backup VLAN (and prod VLAN) - multiple vms on multiple ESX hosts - same issue
VMs can ping backup media server and all other servers across WAN
Netbackup media server can ping all servers on WAN except those on vCenter/ESX
Netbackup media server can ping all physical servers on same backup subnet/VLAN
Two dozen VLANs configured on vCenter ESX 9 node cluster with no issues
VMs on Backup VLAN can ping Netbackup media server but the Netbackup media server can't ping VMs
So, of course, guests backups cannot be configured ... Any help? I have submitted issue to Network dept of our client 
I award all points possible everytime after 72 hrs regardless.