Patent bullshit!!!
Reading the full patent - the only slightly possible patentable thing is the removing of 'expired' items 'on the fly'
The linked list to resolve hash collisions is well known - and the patent references prior art for this
There is nothing in the patent that defines what 'expired' is in this instance, and we can conceive of many methods to define expired so this is not the sole basis of the patent.
So the final and more likely grounds for the patent is 'on the fly' - which is simply that during the linked list iteration phase of a normal search the algorithm checks each node for whether it is expired - and removes it.
I have personally (in 20 years) not seen this 'on the fly' removal - I have seen explicit removal and garbage collection task, but I can not believe for a minute that this was profound, or new in 1996.
I am fairly confident prior art will be found and this Patent will be invalidated, well I bloody hope so!