Packet loss

About: Packet loss is a research topic. Over the lifetime, 21235 publications have been published within this topic receiving 302453 citations.

Head-of-line Blocking in TCP and SCTP: Analysis and Measurements

Abstract: Many signaling protocols in IP networks need a protection against message loss, but they do not require a strict in-sequence data delivery. Since TCP provides reliable in-order transport, end-to-end delays may be unnecessarily increased due to head-of-line blocking. An alternative transport protocol is SCTP, which is optimized for signaling applications and provides mechanisms for reliable, partial-ordered or unordered message delivery. In this paper, we quantify the impact of head-of-line blocking on the response time of transaction-based signaling applications. In order to mitigate this problem, we compare dif- ferent solutions based on TCP and SCTP. Both a new analytical model and measurements on state-of-the-art operating systems show to which extend SCTP can improve transport delays by leveraging transmission over multiple parallel streams or using unordered data delivery. Our analysis reveals that using one or multiple parallel TCP connections can result in much higher end-to-end delays, even for moderate packet loss probabilities. We also observe significant differences in the TCP performance of different operating systems.

Method and system of measuring latency and packet loss in a network

Abstract: The invention provides a method which involves inserting probe packets on a per service basis for transmission on a respective round trip; and for each service using the probe packets to calculate packet latency for probe packets which is representative of packet latency for all packets transmitted for the service. In some embodiments, data plane time stamps are used to accurately time probe latency. The invention also provides a method which involves inserting probe packets on a per service basis for transmission on a respective destination network element; and at the destination network element for a given service using the probe packets to calculate one way packet loss for the service.

FEC and pseudo-ARQ for receiver-driven layered multicast

Abstract: We consider the problem of joint source/channel coding of real-time sources, such as audio and video, for the purpose of multicasting over the Internet. The sender injects into the network multiple source layers and multiple channel (parity) layers, some of which are delayed relative to the source. Each receiver subscribes to the number of source layers and the number of channel layers that optimizes the source-channel rate allocation for that receiver’s available bandwidth and packet loss probability. We augment this layered FEC system with layered ARQ. Although feedback is normally problematic in broadcast situations, ARQ is simulated by having the receivers subscribe and unsubscribe to the delayed channel coding layers to receive missing information. This pseudo-ARQ scheme avoids an implosion of repeat requests at the sender, and is scalable to an unlimited number of receivers. We show gains of up to 18 dB on channels with 20% loss over systems without error control, and additional gains of up to 13 dB when FEC is augmented by pseudo-ARQ in a hybrid system. The hybrid system is controlled by an optimal policy for a Markov decision process.

Multiple packet paths to improve reliability in an IP network

Abstract: The invention replicates a packet requiring high availability and transmits it from two or more ports of a switch, for example a wiring closet Layer 2 switch. The parent packet carries a unique sequence number. The copies of the packet each carry the parent packet's unique sequence number. Each copy of the packet then travels on separate pathways through routers (Layer 3 network devices). The pathways are maintained separate by assigning high costs in a LSP routing sense to links connecting the two paths, and by assigning low costs to links along the desired paths. The two identical packets converge on the destination station. The destination station accepts the first packet with a particular sequence number, and discards any later packets with the same sequence number. In the event that a link in one path has a catastrophic failure, then the packet travelling along the other path reaches the destination station and service remains operative without interruption. The lost path is then recomputed by the a router (if any) still receiving the lost packet. A new non-converging path may be selected if any are available, depending upon the topology. After the disruption is repaired, the original dual pathways may once again be established.