A Novel Packet Marking Function for Real-Time Interactive MPEG-4 Video Applications in a Differentiated Services Network

The future convergence of voice, video and data applications on the Internet requires that next generation technology provides bandwidth and delay guarantees. Current technology trends are moving towards scalable aggregate-based systems where applications are grouped together and guarantees are provided at the aggregate level only. This solution alone is not enough for interactive video applications with sub-second delay bounds. This paper introduces a novel packet marking scheme that controls the end-to-end delay of an individual flow as it traverses a network enabled to supply aggregate- granularity Quality of Service (QoS). IPv6 Hop-by-Hop extension header fields are used to track the packet delay encountered at each network node and autonomous decisions are made on the best queuing strategy to employ. The results of network simulations are presented and it is shown that when the proposed mechanism is employed the requested delay bound is met with a 20% reduction in resource reservation and no packet loss in the network.

用于IP追踪的包标记的注记

拒绝服务攻击是一类最难对付的网络安全问题.近来,人们提出了多种对策.其中由Savage等人提出的一类基于概率的包标记方案比较有研究价值.这里先对拒绝服务攻击的对策作一简述,然后分析了几种包标记方案,指出了它们的一些缺陷,并提出了一些改进措施.其中,对基本型概率包标记方案的一个修改使得计算量大大减少.

IP追踪中的自适应包标记

拒绝服务(DoS)攻击是目前最难处理的网络难题之一.最近,研究人员针对DoS攻击提出了多种方案,这些方案都各有优缺点.其中,由Savage等人提出的概率包标记方案受到了广泛的重视,也有不少的变种出现.在这一类的标记方案中,路由器以固定的概率选择是否标记一个数据包,这导致受害需要较多的数据包进行攻击路径的重构.本文提出一种自适应的标记策略,经实验验证受害者用较少的数据包即可重构攻击路径,这不仅为受害者及早地响应攻击争取了更多的时间,还限制了攻击者的伪造能力.

基于路由器编码的自适应包标记

拒绝服务攻击由于其高发性、大危害、难防范而成为因特网上的一大难题.研究人员为此提出了各种各样的对策,其中概率包标记具有较大的潜力.然而,现有的标记方案都存在各种各样的缺点.提出了一个新的标记方案,与其他标记方法相比,该方案具有反映灵敏,误报率低和计算量小的优点.此外,该方法还限制了攻击者伪造追踪信息的能力.

一种分块包标记的IP追踪方案

DDoS攻击以其高发性、高破坏力和难以防范的特点，近年来成为互联网的主要安全威胁之一．研究者们提出了多种对抗DDoS攻击的方法．：乓中，Savage等人提出的概率包标记方案以其易于实施、消耗资源小等优点，引起人们的重视．然而概率包标记方案存在两个明显缺陷：多攻击路径重构时的高误报率和高计算复杂度．在概率包标记的基础上，提出了一种分块包标记方案，该方案与概率包标记方案相比具有较低的误报率和较低的计算复杂度，因而具有更高的实际应用意义．

Packet error rate and bit error rate non-deterministic relationship in optical network applications

The non-deterministic relationship between Bit Error Rate and Packet Error Rate is demonstrated for an optical media access layer in common use. We show that frequency components of coded, non-random data can cause this relationship. © 2005 Optical Society of America.

Packet classification by multi-level cutting of the classification space: An algorithmic-architectural solution for IP packet classification in next generation networks

Traditionally, the Internet provides only a “best-effort” service, treating all packets going to the same destination equally. However, providing differentiated services for different users based on their quality requirements is increasingly becoming a demanding issue. For this, routers need to have the capability to distinguish and isolate traffic belonging to different flows. This ability to determine the flow each packet belongs to is called packet classification. Technology vendors are reluctant to support algorithmic solutions for classification due to their non-deterministic performance. Although CAMs are favoured by technology vendors due to their deterministic high lookup rates, they suffer from the problems of high power dissipation and high silicon cost. This paper provides a new algorithmic-architectural solution for packet classification that mixes CAMs with algorithms based on multi-level cutting the classification space into smaller spaces. The provided solution utilizes the geometrical distribution of rules in the classification space. It provides the deterministic performance of CAMs, support for dynamic updates, and added flexibility for system designers.

Packet classification by multi-level cutting of the classification space

Traditionally, the Internet provides only a “best-effort” service, treating all packets going to the same destination equally. However, providing differentiated services for different users based on their quality requirements is increasingly becoming a demanding issue. For this, routers need to have the capability to distinguish and isolate traffic belonging to different flows. This ability to determine the flow each packet belongs to is called packet classification. Technology vendors are reluctant to support algorithmic solutions for classification due to their nondeterministic performance. Although content addressable memories (CAMs) are favoured by technology vendors due to their deterministic high-lookup rates, they suffer from the problems of high-power consumption and high-silicon cost. This paper provides a new algorithmic-architectural solution for packet classification that mixes CAMs with algorithms based on multilevel cutting of the classification space into smaller spaces. The provided solution utilizes the geometrical distribution of rules in the classification space. It provides the deterministic performance of CAMs, support for dynamic updates, and added flexibility for system designers.

Random Access over Multi-Packet Reception Channels: A Mean-Field Approach

Thesis (Ph.D.)--University of Washington, 2016-06

Body-shadowing effects in indoor MIMO-OFDM channel capacity

We investigate Multiple-Input and Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems behavior in indoor populated environments that have line-of-site (LoS) between transmitter and receiver arrays. The in-house built MIMO-OFDM packet transmission demonstrator, equipped with four transmitters and four receivers, has been utilized to perform channel measurements at 5.2 GHz. Measurements have been performed using 0 to 3 pedestrians with different antenna arrays (2 £ 2, 3 £ 3 and 4 £ 4). The maximum average capacity for the 2x2 deterministic Fixed SNR scenario is 8.5 dB compared to the 4x4 deterministic scenario that has a maximum average capacity of 16.2 dB, thus an increment of 8 dB in average capacity has been measured when the array size increases from 2x2 to 4x4. In addition a regular variation has been observed for Random scenarios compared to the deterministic scenarios. An incremental trend in average channel capacity for both deterministic and random pedestrian movements has been observed with increasing number of pedestrian and antennas. In deterministic scenarios, the variations in average channel capacity are more noticeable than for the random scenarios due to a more prolonged and controlled body-shadowing effect. Moreover due to the frequent Los blocking and fixed transmission power a slight decrement have been observed in the spread between the maximum and minimum capacity with random fixed Tx power scenario.