2,775 research outputs found
Per-hop Internet Measurement Protocols
Accurately measuring per-hop packet dynamics on an Internet path is difficult. Currently available techniques have many well-known limitations that can make it difficult to accurately measure per-hop packet dynamics. Much of the difficulty of per-hop measurement is due to the lack of protocol support available to measure an Internet path on a per-hop basis. This thesis classifies common weaknesses and describes a protocol for per-hop measurement of Internet packet dynamics, known as the IP Measurement Protocol, or IPMP. With IPMP, a specially formed probe packet collects information from intermediate routers on the packet's dynamics as the packet is forwarded. This information includes an IP address from the interface that received the packet, a timestamp that records when the packet was received, and a counter that records the arrival order of echo packets belonging to the same flow. Probing a path with IPMP allows the topology of the path to be directly determined, and for direct measurement of per-hop behaviours such as queueing delay, jitter, reordering, and loss. This is useful in many operational situations, as well as for researchers in characterising Internet behaviour.
IPMP's design goals of being tightly constrained and easy to implement are tested by building implementations in hardware and software. Implementations of IPMP presented in this thesis show that an IPMP measurement probe can be processed in hardware without delaying the packet, and processed in software with little overhead. This thesis presents IPMP-based measurement techniques for measuring per-hop packet delay, jitter, loss, reordering, and capacity that are more robust, require less probes to be sent, and are potentially more accurate and convenient than corresponding measurement techniques that do not use IPMP
Packet loss characteristics of IPTV-like traffic on residential links
Packet loss is one of the principal threats to quality of experience for IPTV systems. However, the packet loss characteristics of the residential access networks which carry IPTV are not widely understood. We present packet level measurements of streaming IPTV-like traffic over four residential access links, and describe the extent and nature of packet loss we encountered. We discuss the likely impact of these losses for IPTV traffic, and outline steps which can ameliorate this
DoS protection for a Pragmatic Multiservice Network Based on Programmable Networks
Proceedings of First International IFIP TC6 Conference, AN 2006, Paris, France, September 27-29, 2006.We propose a scenario of a multiservice network, based on pragmatic
ideas of programmable networks. Active routers are capable of processing both
active and legacy packets. This scenario is vulnerable to a Denial of Service attack,
which consists in inserting false legacy packets into active routers. We
propose a mechanism for detecting the injection of fake legacy packets into active
routers. This mechanism consists in exchanging accounting information on
the traffic between neighboring active routers. The exchange of accounting information
must be carried out in a secure way using secure active packets. The
proposed mechanism is sensitive to the loss of packets. To deal with this problem
some improvements in the mechanism has been proposed. An important issue
is the procedure for discharging packets when an attack has been detected.
We propose an easy and efficient mechanism that would be improved in future
work.Publicad
Transport congestion events detection (TCED): towards decorrelating congestion detection from TCP
TCP (Transmission Control Protocol) uses a loss-based algorithm to estimate whether the network is congested or not.
The main difficulty for this algorithm is to distinguish spurious from real network congestion events. Other research studies have proposed to enhance the reliability of this congestion estimation by modifying the internal TCP algorithm.
In this paper, we propose an original congestion event algorithm implemented independently of the TCP source code. Basically, we propose a modular architecture to implement a congestion event detection algorithm to cope with the increasing complexity of the TCP code and we use it to understand why some spurious congestion events might not be
detected in some complex cases. We show that our proposal is able to increase the reliability of TCP NewReno congestion detection algorithm that might help to the design of detection criterion independent of the TCP code. We find out that solutions based only on RTT (Round-Trip Time) estimation are not accurate enough to cover all existing cases.
Furthermore, we evaluate our algorithm with and without network reordering where other inaccuracies, not previously
identified, occur
Verifiable Network-Performance Measurements
In the current Internet, there is no clean way for affected parties to react
to poor forwarding performance: when a domain violates its Service Level
Agreement (SLA) with a contractual partner, the partner must resort to ad-hoc
probing-based monitoring to determine the existence and extent of the
violation. Instead, we propose a new, systematic approach to the problem of
forwarding-performance verification. Our mechanism relies on voluntary
reporting, allowing each domain to disclose its loss and delay performance to
its neighbors; it does not disclose any information regarding the participating
domains' topology or routing policies beyond what is already publicly
available. Most importantly, it enables verifiable performance measurements,
i.e., domains cannot abuse it to significantly exaggerate their performance.
Finally, our mechanism is tunable, allowing each participating domain to
determine how many resources to devote to it independently (i.e., without any
inter-domain coordination), exposing a controllable trade-off between
performance-verification quality and resource consumption. Our mechanism comes
at the cost of deploying modest functionality at the participating domains'
border routers; we show that it requires reasonable processing and memory
resources within modern network capabilities.Comment: 14 page
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