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Ipsec vs Isakmp SA lifetimes

I just had a general quesiton regarding SA lifetimes for both isakmp and ipsec. I know that when the the timeouts values (either time or number of bytes) are reached then new SAs are negotiated. What happens when both the isakmp and ipsec SA's have to negotitate new SA's at the same time? If the ipsec SA needs to be negotiated but the isakmp is still negotiating its new SA does ipsec know how to handle this? Thanks.

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Re: Ipsec vs Isakmp SA lifetimes

I guess the mechanism is the same one that ensures that on startup the IPSec SA negotiation starts after ISAKMP negotiation is over. In case a state comes where the two SA lifetimes expire simultaneously, the ISAKMP SA re-negotiation process should get over before IPSec SA negotiation starts. However, such a state will not be reached since a new SA is re-negotiated before the old one expires, thus preventing a period where traffic has to be dropped.

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