IPSEC heartbeat in CISCO

[frenou at CF6.FR]

Hello,
I'm running IPSec on CISCO routers to build VPN betwween some sites.Those
sites also have a low and expensive ;-) bandwith private WAN. What I want is
to detect a failure of the VPN (either Internet access is down either the
peer is down) so that I can re-route traffic on my private WAN.
The hearbeat mechanism (as defined in IPSEC drafts) seems a perfect
candidate for this function but is it supported by CISCO( I can't find any
information in docs)?
Anyone has an idea?
TIA

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