Next: NetPIPE Design
In recent years, much research has been directed towards evaluating the
performance of high speed networks. [2,3,4,5]
The design of NetPIPE, a network protocol independent performance evaluator,
has been motivated by the need to assess the performance of communication
bound applications. NetPIPE helps answer questions that surround network
communications inherent to these applications. These applications include
file transfer and graphical simulations for display in a virtual reality
environment, such as CAVE  applications,
which require frame transfers from a compute server. While file transfer
applications allow streaming of data, a graphical simulation requires blocks
of data transmitted at regular intervals to maintain full-motion video.
The size of each block and the number of frames per second are enough to
specify a minimum network throughput required to maintain realistic animation.
With the applications in mind, several questions can be asked in reference
to the network communication. For instance, how soon will a given data block
of size k arrive at its destination? Which network and protocol
will transmit size k blocks the fastest? What is a given network's
effective maximum throughput and saturation level? Does there exist a block
size k for which the throughput is maximized? How much communication
overhead is due to the network communication protocol layer(s)? How quickly
will a small (< 1 kbyte) control message arrive, and which network and
protocol are best for this purpose?
The answers to such questions are not always straightforward and easy to
obtain with current network performance tools. The two most popular tools,
ttcp  and netperf
, are based on the TCP/IP [7,8,9]
communications protocol. While netperf has the ability to map network performance,
comparing network protocols with these tools is difficult if not impossible.
Finding the effective maximum bandwidth using ttcp is an exercise in delving
into protocol internals. Knowledge of the appropriate buffer size, alignment
address, and protocol settings is required to achieve data transfer at the
effective maximum bandwidth.
With the various network types available (ATM, FDDI, HIPPI, Ethernet, etc.),
it is difficult to select a network infrastructure which best satisfies
an application's bandwidth requirement. The design of NetPIPE has been motivated
by the need to select a network infrastructure for various types of applications
and communication with a CAVE virtual reality environment. In addition NetPIPE
provides for visualization of network performance and the information necessary
to answer the above questions.
This paper presents NetPIPE and some of the results obtained through its
use. In the next section, we present the NetPIPE driver and its underlying
principles. Sections 3 and 4 consist of results obtained using NetPIPE in
a variety of network infrastructures. A summary and conclusion with answers
to the questions posed above can be found in Section 5.
Next: NetPIPE Design
Fri Apr 5 12:14:32 CST 1996