# Impact of Traffic Characteristics on Request Aggregation in an NDN Router

## TL;DR

This paper analyzes how traffic patterns and request aggregation via PIT in NDN routers affect bandwidth efficiency, introducing a new mathematical model and evaluating cache policies under realistic traffic conditions.

## Contribution

It presents a novel, more general mathematical framework for caching in NDN, considering non-zero download delays and alternative cache policies like LRU filters.

## Key findings

- PIT significantly reduces upstream bandwidth mainly for small content catalogs.
- LRU filter improves cache hit rate in non-ZDD scenarios.
- Effectiveness of filters depends on catalog size and traffic intensity.

## Abstract

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.