How to trigger link down, dhcp release, renew on wan if using "router on a stick

[GoldServe]

I guess this affects virtual environments too but say I have WAN1 and WAN2 on their own VLAN and in ESXI, I have a VSWITCH with different port groups assigned to different VLANs. When the modem reboots, there is no way for pFSense to know the connection has gone down, release WAN DHCP and renew the link. How do people overcome this problem?

[johnpoz]

why would you need to do this?  My modem has gone down in the past - have never had to renew dhcp lease on such an event.  My pfsense is on esxi.