Dead peer detection not working !!! Help please...

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Sep 3rd, 2007
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I have two 2811 VPN routers connected via several switches. Static crypto maps and isakmp keepalives at 10seconds.

Tunnel is up and working, encrypting traffc between loopbacks on the 2811s when I do extended pings.

Everything works fine. I do a show crypto isakmp sa detail and can see the security association and remaining lifetime.

I now kill a link betwen the switches, isolating the 2811's. I can no longer do my extended ping between the loopbacks between the 2811's, as would be expected. However, why isn't the DPD taking the SA down? When I do a show cryto isakmp sa detail again, there is no difference to the output when the VPN was up and running. I AM generating traffic so why isn't the SA being deleted? I have NTP running with teh source address as the loopbacks so there is always interesting traffic.

If I use periodic keepalives it works properly and the SA drops out. However, I am labbing this problem because with my customer a 6500 VPN SPA is the tunnel endpoint and this does not support periodic keepalives !!!

Thanks for your help.


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umedryk Fri, 09/07/2007 - 10:13
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Using periodic DPD potentially allows the router to detect an unresponsive IKE peer with better response time when compared to on-demand DPD. However, use of periodic DPD incurs extra overhead. When communicating to large numbers of IKE peers, you should consider using on-demand DPD instead.


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