Internet is a packet switched heterogeneous network. Much research can be done in order to learn about the properties of and extend the capabilities of the Internet. In this thesis three studies around this topic are presented. First study: proportional loss rate differentiation is a quality of service problem where network traffic are divided into classes, and each class receives a loss rate proportional to another class. Simulations are used to show that robust proportional loss rate differentiation can be obtained by using a relatively simple algorithm. Second study: the use of IPv4 options are often suggested to be used for extending the basic IPv4 protocol. Measurements are performed by sending sample packets show that the use of IPv4 options is problematic. Use of options leads to higher delay, although the difference is small. Furthermore, the jitter and loss rate increases. While the increased delay and jitter may be tolerable, the increased loss rate is probably not. Third study: merging Internet technologies, such as network address translation, mobile IP, firewalls etc., indicates that the Internet architecture is insufficient for current needs. The split naming/forwarding network architecture, is a network architecture intended to be simple and flexible. This architecture is described and it is argued that it is an interesting alternative to the current Internet architecture.

Real-time multimedia transfer through the Internet becomes more difficult when wireless links are in the path, due to the time varying channel capacity, from interference and multipath fading effects which introduce additional stochastic variations beyond the wireline network traffic effects. These wireless variations create problems for existing end-to-end rate adaption using feedback. This paper introduces a framework for cross-layer solutions to the streaming video problem with a focus on graceful degradation under network congestion and/or wireless fading effects without direct coordination between source coder, channel coder, and physical layer modulator. The solution presented includes network transportation and wireless based optimizations and requires little reliance upon end-to-end rate adaption. The suggested method uses progressively coded, leaky prediction source data and physical layer based rate adaption in concert with error tolerant network protocols.

IP version 4 specifies options that extends the basic IP header and also allow new functions to be added to IP without breaking existing implementations. Since options must always be inspected routers, it is generally believed that routers prioritize ordinary packets over packets carrying options in a way that significantly impacts the performance of options. This article presents an experiment based on end-to-end probing using UDP packets, capturing the performance penalties associated with IPv4 options. Analysis of experiment results quantifies the impact of IPv4 options on forwarding performance in terms of delay, jitter and loss rate. From the analysis it can be concluded that there is a slight increase in delay and jitter and severely increased loss rate.

IP version 4 specifies options that extend the basic IP header and also allow new functions to be added to IP without breaking existing implementations. Since options must always be inspected at routers, it is generally believed that routers prioritize ordinary packets over packets carrying options in a way that significantly impacts the performance of options. This article presents an experiment based on end-to-end probing using UDP packets, capturing the performance penalties associated with IPv4 options. Analysis of experiment results quantifies the impact of IPv4 options on forwarding performance in terms of delay, jitter and loss rate. From the analysis it can be concluded that there is a slight increase in delay and jitter and a severe increase in loss rate

The evolution of the Internet is inhibited by the routing system's lack of ability to provide instant routes at host granularity. We argue that it is necessary to divide the addressing into naming and location and use separate mechanisms for the two functions. We present the split naming/forwarding architecture (SNF), which divides the network layer into naming and forwarding layers. The design rationale of SNF is discussed and we describe an implementation for deployment on top of current network infrastructures.

Recent extensions to the Internet architecture allow assignment of different levels of drop precedence to IP packets. This paper examines differentiation predictability and implementation complexity in creation of proportional lossrate (PLR) differentiation between drop precedence levels. PLR differentiation means that fixed loss-rate ratios between different traffic aggregates are provided independent of traffic loads. To provide such differentiation, running estimates of loss-rates can be used as feedback to keep loss-rate ratios fixed at varying traffic loads. In this paper, we define a loss-rate estimator based on average drop distances (ADDs). The ADD estimator is compared with an estimator that uses a loss history table (LHT) to calculate loss-rates. We show, through simulations, that the ADD estimator gives more predictable PLR differentiation than the LHT estimator. In addition, we show that a PLR dropper using the ADD estimator can be implemented efficiently.