SESSION: Network Protocol Tuning
CHAIR:
TIME: Tuesday 11/19 10:30-Noon
ROOM: 314-315

1. pap270
TITLE: The Effects of Systemic Packet Loss on Aggregate TCP Flows
AUTHORS: Thomas J. Hacker (University of Michigan)
Brian D. Noble (University of Michigan)
Brian D. Athey (University of Michigan)

ABSTRACT:
The use of parallel TCP connections to increase throughput for bulk transfers is common practice within the high performance computing community. However, the effectiveness, fairness, and efficiency of data transfers across parallel connections is unclear. This paper considers the impact of systemic non-congestion related packet loss on the effectiveness, fairness, and efficiency of parallel TCP transmissions. The results indicate that parallel connections are effective at increasing aggregate throughput, and increase the overall efficiency of the network bottleneck. In the presence of congestion related losses, parallel flows steal bandwidth from other single stream flows. A simple modification is presented that reduces the fairness problems when congestion is present, but retains effectiveness and efficiency.

2. pap320
TITLE: Implementation and Evaluation of A QoS-Capable Cluster-Based IP Router
AUTHORS: Prashant Pradhan (State University of New York at Stony Brook)
Tzi-cker Chiueh (State University of New York at Stony Brook)

ABSTRACT:
A major challenge in Internet edge router design is to support both high packet forwarding performance and versatile and efficient packet processing capabilities. The thesis of this research project is that a cluster of PCs connected by a high-speed system area network provides an effective hardware platform for building routers to be used at the edges of the Internet. This paper describes a scalable and extensible edge router architecture called Panama, which supports a novel aggregate route caching scheme, a real-time link scheduling algorithm whose performance overhead is independent of the number of real-time flows, a highly efficient kernel extension mechanism to safely load networking software extensions dynamically, and an integrated resource scheduler which ensures that real-time flows with additional packet processing requirements still meet their end-to-end performance requirements. This paper describes the implementation and evaluation of the first Panama prototype based on a cluster of PCs and Myrinet.

3. pap151
TITLE: A TCP Tuning Daemon
AUTHORS: Thomas Dunigan (Oak Ridge National Lab)
Matt Mathis (Pittsburgh Supercomputing Center)
Brian Tierney (Lawrence Berkeley National Lab)

ABSTRACT:
Many high performance distributed applications require high network throughput but are able to achieve only a small fraction of the available bandwidth. A common cause of this problem is improperly tuned network settings. Tuning techniques, such as setting the correct TCP buffers and using parallel streams, are well known in th e networking community, but outside the networking community they are infrequently applied. In this paper, we describe a tuning daemon that uses TCP instrumentation data from the Unix kernel to transparently tune TCP parameters for specified individual flows over designated paths. No modifications are required to the application, and the user does not need to understand network or TCP characteristics.