ANNOUNCEMENT: Release of U-Net 2.1 software distribution
Matt Welsh, mdw@cs.berkeley.edu, University of California, Berkeley
http://www.cs.berkeley.edu/~mdw/projects/unet/

U-Net is a protected, user-level network architecture for low-latency
and high-bandwidth communication. ATM, Fast Ethernet, and Myrinet are the
network media supported with this release on a variety of network interface 
cards and operating systems. Benchmarks have demonstrated round-trip 
(ping-pong) latencies of as low as 26 microseconds (Myrinet), 60 
microseconds (Fast Ethernet) and 65 microseconds (ATM) for 40-byte messages.
The full bandwidth of the physical network can be exploited using small
messages (800 - 1000 bytes).

The primary application for U-Net is low-latency communication in
workstation clusters, for parallel and distributed computing tasks.
The Active Messages communication layer and Split-C parallel language 
have both been ported to U-Net, and demonstrate that a cluster of 
workstations communicating via U-Net can rival the performance
of commerical MPPs.

U-Net is different than other messaging and fast networking layers for
workstation clusters in a number of ways:

  * U-Net allows multiple user applications to safely share the network.
    This is fundamental to the U-Net design - that multiple applications
    have _protected_ fast network access. This not only enables multiple
    cooperating processes to coexist within a cluster environment but also
    makes application development and debugging a much simpler task.

  * U-Net is _not_ a 'messaging layer' per se; rather it is a very simple,
    fast network interface enabling applications to simply transmit and
    receive messages of any format and size (up to a network-defined 
    maximum), without flow-control or error-correction/detection other
    than that provided by the physical network. In this way applications
    are able to implement their own protocols in user space, potentially
    allowing for much better customization of protocol code to application
    needs than a pre-defined messaging layer. For example, a video-processing
    application could implement its own video transport protocol which 
    performs better and has better flow-control behavior than traditional
    parallel-messaging protocols.

  * U-Net does not assume homogeneity between cluster nodes. In fact, a 
    single node could communicate over U-Net on multiple types of network 
    interfaces, allowing the node to act as a U-Net "bridge".

  * U-Net runs on a variety of commodity network interfaces and host
    operating systems. This release supports the Myricom PCI and SBus Myrinet 
    interface, the DECChip 'Tulip' 21140 PCI Fast Ethernet interface, and 
    the FORE Systems PCA-200 and SBA-200 ATM interfaces. Supported operating
    systems include Linux, SunOS 4.x, Solaris 2.x, and BSDI 3.0. A separate
    release for Windows NT 4.0 is available from Cornell (see the web page
    above). 

  * All source code for U-Net is provided and distributed under a BSD-like
    license, with the exception of the FORE PCA-200/SBA-200 i960 firmware.
    This should facilitate easy porting to other architectures.

U-Net is a project of Cornell University and the University of California,
Berkeley. For more information and details on obtaining the release, please
see http://www.cs.berkeley.edu/~mdw/projects/unet/.

M. Welsh, mdw@cs.berkeley.edu