TY  - RPRT
A1  - Grigorjew, Alexej
A1  - Schumann, Lukas Kilian
A1  - Diederich, Philip
A1  - Hoßfeld, Tobias
A1  - Kellerer, Wolfgang
T1  - Understanding the Performance of Different Packet Reception and Timestamping Methods in Linux
T2  - KuVS Fachgespräch - Würzburg Workshop on Modeling, Analysis and Simulation of Next-Generation Communication Networks 2023 (WueWoWAS’23)
N2  - This document briefly presents some renowned packet reception techniques for network packets in Linux systems. Further, it compares their performance when measuring packet timestamps with respect to throughput and accuracy. Both software and hardware timestamps are compared, and various parameters are examined, including frame size, link speed, network interface card, and CPU load. The results indicate that hardware timestamping offers significantly better accuracy with no downsides, and that packet reception techniques that avoid system calls offer superior measurement throughput.
KW  - packet reception method
KW  - timestamping method
KW  - Linux
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-322064
ER  - 
TY  - RPRT
A1  - Grigorjew, Alexej
A1  - Metzger, Florian
A1  - Hoßfeld, Tobias
A1  - Specht, Johannes
A1  - Götz, Franz-Josef
A1  - Schmitt, Jürgen
A1  - Chen, Feng
T1  - Technical Report on Bridge-Local Guaranteed Latency with Strict Priority Scheduling
N2  - Bridge-local latency computation is often regarded with caution, as historic efforts with the Credit-Based Shaper (CBS) showed that CBS requires network wide information for tight bounds. Recently, new shaping mechanisms and timed gates were applied to achieve such guarantees nonetheless, but they require support for these new mechanisms in the forwarding devices.

This document presents a per-hop latency bound for individual streams in a class-based network that applies the IEEE 802.1Q strict priority transmission selection algorithm. It is based on self-pacing talkers and uses the accumulated latency fields during the reservation process to provide upper bounds with bridge-local information. The presented delay bound is proven mathematically and then evaluated with respect to its accuracy. It indicates the required information that must be provided for admission control, e.g., implemented by a resource reservation protocol such as IEEE 802.1Qdd. Further, it hints at potential improvements regarding new mechanisms and higher accuracy given more information.
KW  - Echtzeit
KW  - Rechnernetz
KW  - Latenz
KW  - Ethernet
KW  - Latency Bound
KW  - Formal analysis
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-198310
ER  - 
TY  - RPRT
A1  - Grigorjew, Alexej
A1  - Metzger, Florian
A1  - Hoßfeld, Tobias
A1  - Specht, Johannes
A1  - Götz, Franz-Josef
A1  - Chen, Feng
A1  - Schmitt, Jürgen
T1  - Asynchronous Traffic Shaping with Jitter Control
N2  - Asynchronous Traffic Shaping enabled bounded latency with low complexity for time sensitive networking without the need for time synchronization. However, its main focus is the guaranteed maximum delay. Jitter-sensitive applications may still be forced towards synchronization. This work proposes traffic damping to reduce end-to-end delay jitter. It discusses its application and shows that both the prerequisites and the guaranteed delay of traffic damping and ATS are very similar. Finally, it presents a brief evaluation of delay jitter in an example topology by means of a simulation and worst case estimation.
KW  - Echtzeit
KW  - Rechnernetz
KW  - Latenz
KW  - Ethernet
KW  - TSN
KW  - jitter
KW  - traffic damping
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-205824
ER  - 
TY  - RPRT
A1  - Grigorjew, Alexej
A1  - Diederich, Philip
A1  - Hoßfeld, Tobias
A1  - Kellerer, Wolfgang
T1  - Affordable Measurement Setups for Networking Device Latency with Sub-Microsecond Accuracy
T2  - Würzburg Workshop on Next-Generation Communication Networks (WueWoWas'22)
N2  - This document presents a networking latency measurement setup that focuses on affordability and universal applicability, and can provide sub-microsecond accuracy. It explains the prerequisites, hardware choices, and considerations to respect during measurement. In addition, it discusses the necessity for exhaustive latency measurements when dealing with high availability and low latency requirements. Preliminary results show that the accuracy is within ±0.02 μs when used with the Intel I350-T2 network adapter.
KW  - Datennetz
KW  - latency
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-280751
ER  -