Verify VPN is working from logs

[Tarquin Joseph <tarquin_(_dot_)_joseph_(_at_)_gmail_(_dot_)_com>]

Hello,

I've configured a VPN link between two NET4501's running OpenBSD 3.5
using the example given man vpn.

My question is this:  after running isakmpd -d -D A=99 on both boxes,
what should I look for to verify that the VPN has negotiated properly.

Thanks in advance for responses.

Tarquin.