Large TCP Windows In order to achieve high data rates with TCP over "long fat networks", i.e. network paths with a large bandwidth delay product, TCP sinks (that is ...

TCP Window Scaling Option TCP as originally specified only allows for windows up to 65536 bytes, because the window related protocol fields all have a width of 16 ...

InfiniBand InfiniBand is a high performance network architecture developed by the IBTA (InfiniBand Trade Association). IBTA is a group of 220 or more companies founded ...

Layer 2 traceroute Traceroute is a well known and helpful tool used to display the route of packets across the network. Available on most operating system, traceroute ...

Welcome to the eduPERT Knowledge Base. This is a wiki that collects useful information on how to get good performance out of networks, in particular research networks ...

Ethernet OAM Operations, Administration Maintenance (OAM) refers to protocols and mechanisms that help operator to achieve the so called FCAPS functionalities. FCAPS ...

Propagation Delay The propagation delay is the time it takes for a signal to propagate. It depends on the distance traveled, and the specific propagation speed ...

Serialization Delay (or Transmission Delay) Serialization delay is the time it takes for a unit of data, such as a packet, to be serialized for transmission on a narrow ...

Statistics for PERTKB Web Month: Topic views: Topic saves: File uploads: Most popular topic views: Top contributors for topic save and ...

IP Performance Metrics (IPPM) Working Group An IETF Working Group that has been chartered in 1997 to define metrics for network performance. Over the years, the group ...

"NewReno" TCP NewReno is an improvement on Reno TCP, which improves the performance of handling loss of multiple segments in a single round trip time in the absence ...

Sizing of Network Buffers Where temporary congestion cannot be avoided, some buffering in network nodes is required (in routers and other packet forwarding devices ...

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Bandwidth Measurement Tools (Click on blue headings to link through to detailed tool descriptions and examples) Iperf Iperf is a tool to measure maximum TCP bandwidth ...

TCP Flow Control Note: This topic describes the Reno enhancement of classical "Van Jacobson" or Tahoe congestion control. There have been many suggestions for improving ...

TCP's Initial Congestion Window (ICW, IW or initcwnd) The initial version of TCP Congestion Control specified that the congestion window should start at the maximum ...

Iperf Iperf is a tool to measure TCP throughput and available bandwidth, allowing the tuning of various parameters and UDP characteristics. Iperf reports bandwidth ...

SmokePing Smokeping is a software based measurement framework that uses various software modules (called probes) to measure round trip times, packet losses and availability ...

SmokeTrace Some versions of the SmokePing active measurement and visualization tool included a tool called SmokeTrace. Like SmokePing, SmokeTrace runs on a Web server ...

User Perceived Performance User perceived performance of network applications is made up of a number of mainly qualitative metrics, some of which are in conflict with ...

Responsiveness One of the most important user experiences in networking applications is the perception of responsiveness. If end users feel that an application is ...

Support for Large Frames/Packets ("Jumbo MTU") On current research networks (and most other parts of the Internet), end nodes (hosts) are restricted to a 1500 byte ...

NREN Tools and Statistics A list of all NRENs and other networks who offer statistics/info for their networks and/or have tools available for PERT staff to use. ...

fping fping is a ping like program which uses the Internet Control Message Protocol (ICMP) echo request to determine if a host is up. fping is different from ...

NDT (Network Diagnostic Tool) NDT can be used to check the TCP configuration of any host that can run Java applets. The client connects to a Web page containing a ...

UDT (UDP based Data Transfer Protocol) UDT is a UDP based protocol for bulk data transfers over high speed (1 Gb/s and above) wide area networks. It was used in the ...

GridFTP GridFTP is a file transfer protocol that uses parallel streams to provide good bulk performance over LFNs. The underlying transport can be TCP or UDT. GridFTP ...

Wireshark Wireshark is a packet capture/analysis tool, similar to tcpdump but much more elaborate. It has a graphical user interface (GUI) which allows "drilling ...

Web10G Web10G is a follow up of the Web100 project, which had given us things like the web100 TCP instrumentation in the Linux kernel (underlying tools such as ...

Latest News Windows 7 / Vista / 2008 TCP/IP tweaks On Speedguide.net there is a great article about the TCP/IP Stack tuning possibilities in Windows 7/Vista/2008 ...

G Eacute;ANT Tools PERT Staff can access a range of tools for checking the status of the G Eacute;ANT network by logging into https://tools.geant.net/portal/ (if a ...

TODO The PERT Knowledge Base is a Wiki, so it can be edited by anyone after a simple registration procedure. Here are a few suggestions for further developing the ...

Interrupt Coalescence (also called Interrupt Moderation , Interrupt Blanking , or Interrupt Throttling ) A common bottleneck for high speed data transfers is the ...

Social Web Experiment The eduPERT Knowledge Base has grown to be a useful resource for practitioners who want to improve performance of networks and networked applications ...

PERTKB Web Preferences The following settings are web preferences of the PERTKB web. These preferences overwrite the site level preferences in ., and can be ...

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Web100 Linux Kernel Extensions The Web100 project was run by PSC (Pittsburgh Supercomputing Center), the NCAA and NCSA. It was funded by the US National Science ...

Automatic Tuning of TCP Buffers Note: This mechanism is sometimes referred to as "Dynamic Right Sizing" (DRS). The issues mentioned under "Large TCP Windows" are ...

Measurement Tools Traceroute like Tools: traceroute, MTR, PingPlotter, lft, tracepath, traceproto There is a large and growing number of path measurement tools derived ...

File Transfer A common problem for many scientific applications is the replication of often large data sets (files) from one system to another. (For the generalized ...

TCP Low Priority (TCP LP) This TCP variant was developed at Rice University by a group comprising Ed Knightly, Aleksandar Kuzmanovic and YuZen Chen. The basic goal ...

TCP Veno Veno claims to improve certain perceived shortcomings in TCP Vegas: It competes better with TCP Reno and similar implementations under congestion ...

TCP Vegas TCP Vegas uses variations in measured throughput as an indication of congestion, in addition to packet loss. It also uses finer timer granularity compared ...

High Speed TCP Variants There have been numerous ideas for improving TCP over the years. Some of those ideas have been adopted by mainstream operations (after thorough ...

Compound TCP Compound TCP was developed by Microsoft for the "Vista" operating system. It combines two types of congestion control mechanisms: TCP Reno's loss based ...

HADES Hades Active Delay Evaluation System (HADES) devices (previously called IPPM devices) were developed by the WiN Labor at RRZE (Regional Computing Centre Erlangen ...

eduPERT Training, Zurich, 18/19 November 2010 We held another successful training event in November 2010a, with 17 attendees from various NRENs including some countries ...

News Archive (2009) For current news, check out the LatestNews section FreeBSD 8.0 Released Release 8.0 of the FreeBSD operating system was released on 24 November ...

Mirror Servers In the late 1980s and early 1990, FTP traffic from popular file archives accounted for a large part of the traffic on the Internet (and contributed ...

Multicast The most common mode of data transfer in IP networks is "unicast": A source sends a packet to a (single) destination. Various other modes are supported ...