Cache blocking of specific data to secondary cache with a first and a second OR circuit

A cache blocking mechanism ensures that transient data is not stored in a secondary cache of a router by managing a designated set of buffers in a main memory of the router. The mechanism defines a window of virtual addresses that map to predetermined physical memory addresses associated with the set of buffers; in the illustrative embodiment, only transient data may be stored in these buffers. The mechanism further blocks write requests directed to these predetermined memory buffers from propagating to the secondary cache, thereby precluding storage of transient data in the cache.