VPN connections appear to be flakey

["Russell P. Sutherland" <russ_(_at_)_quist_(_dot_)_ca>]

I've set up a two VPNs using central IPSec gaetway with
two satellites. Here's the diagram:


        -------- remote network (A)                -------- central network (B)
           |                                         |
      VPN gateway                                VPN gateway
           |                                         |
           MNSi PPOE connection ---- Internet ----- AT&T DSL connection
                                        |
                                        |
                                 Rogers DHCP connection
                                        |
                                        VPN gateway
                                        |
                                -------------- remote network (C)

The central VPN machine at B listens for phase I connections from anyone
as both A and C are not necessarily static IP addresses. It sets
up phase II connections with networks A and C.

Normally things work well. Once per day however, IP connectivity is lost
from the perspective of a host on A trying to connect to a service on
network B. When in this disconnected state, if I log into the VPN
gateway machine at B, I can stop the isakmpd daemon, flush all the encap
routes and restart isakmpd. Bingo. Connectivity is regained. I've
"heard" that connectivit can be lost when the phase II connections
re-key. Is this true? Can anyone think of anything else that might
be worth investigating to remedy the problem?

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