The paper revisits the performance evaluation of caching in a Named Data
Networking (NDN) router where the content store (CS) is supplemented by a
pending interest table (PIT). The PIT aggregates requests for a given content
that arrive within the download delay and thus brings an additional reduction
in upstream bandwidth usage beyond that due to CS hits. We extend prior work on
caching with non-zero download delay (non-ZDD) by proposing a novel
mathematical framework that is more easily applicable to general traffic models
and by considering alternative cache insertion policies. Specifically we
evaluate the use of an LRU filter to improve CS hit rate performance in this
non-ZDD context. We also consider the impact of time locality in demand due to
finite content lifetimes. The models are used to quantify the impact of the PIT
on upstream bandwidth reduction, demonstrating notably that this is significant
only for relatively small content catalogues or high average request rate per
content. We further explore how the effectiveness of the filter with finite
content lifetimes depends on catalogue size and traffic intensity
