Protocol Boosters and P4 Project


Protocol Boosters for Distributed Systems is a DARPA/ITO funded research project to improve the performance of heterogeneous distributed computing systems by improving the performance of the communication protocols that are used by the nodes of the distributed systems.

Protocol Boosters

The basic approach of protocol boosters is to increase protocol performance by dynamically avoiding any unnecessary protocol processing. Most existing approaches use the same protocol for all communications, and thus perform no protocol optimization. Other existing approaches determine the characteristics of the worst possible path between the transmitter and receiver and construct an appropriate protocol for this communication. Although this approach provides some optimization, it suffers from several drawbacks. One drawback is that optimization is based on the worst path, which may be considerably different from the average path. Another drawback is that the transmitter and receiver must somehow determine the characteristics of the paths between them, perhaps using a large database.

Protocol boosters work by dynamically optimizing the communication protocol. Each transmitter uses only as much protocol functionality as necessary to send data on its local network. As data travels through the network, protocol functionality is added as needed within the network itself. Thus, the minimum protocol functionality is used regardless of the path that the data travels. Protocols are carefully designed to minimize the amount of processing needed to add incremental protocol functionality. Despite the fact that protocol functionality is added by processors within the network, the protocol retains all of the characteristics associated with end-to-end protocols, such as robustness.


P4: Programmable Protocol Processing Pipeline:
Hardware support for Protocol Boosters using FPGA technology. Hardware/software project by Ilija Hadzic (VHDL designs, board designs and software are available to public).

FreeBSD Protocol Boosters implementation:
Protocol Boosters support added to FreeBSD TCP/IP protocol stack. Software project by Alex Mallet and Jeffrey D. Chung ( software available).

VENUS: Virtual Environment  Network Using Satellites:
A large-scale application using Protcol Boosters. Software project by Sanjay Udani.


D.C.Feldmeier, A.J. McAuley, J.M. Smith, D. Bakin, W.S. Marcus, T. Raleigh, "Protocol Boosters", IEEE JSAC, Special Issue on Protocol Architectures for 21st Century, vol 16, no. 3, pp. 437-444, April 1998.

A. Mallet, J.D. Chung, J.M.Smith, "Operating Systems Support for Protocol Boosters",  HIPPARCH Workshop, June 1997.

I. Hadzic, J.M.Smith, "P4: A platform for FPGA implementation of Protocol Boosters", 7th International Workshop on Field Programmable Logic and Applications (FPL97), Sept. 1997

I. Hadzic, J.M.Smith, W.S. Marcus, "On-the-fly Programmable Hardware for Networks", in Proceedings of IEEE Globecom 1998

I. Hadzic, "Signalling Protocol for P4 (SPP4)", version 1.0, Techical report, MS-CIS-98-20, University of Pennsylvania, Department of Computer Science, 1998

S. Udani, "PhD Thesis Proposal",, University of Pennsylvania, Department of Computer Science

S. Udani, J.M. Smith, D.J. Farber, "VENUS: A Virtual Environment Network Using Satellites",, University of Pennsylvania, Department of Computer Science

W.S. Marcus, I. Hadzic, A.J. McAuley, J.M. Smith, Protocol Boosters: Applying Programmability to Network Infrastructures, IEEE Communications Magazine, vol. 36, no. 10, pp. 79-83.

J.M. Smith, I. Hadzic, W.S. Marcus, ACTIVE Interconnects: Let's have some guts!, Hot Interconnects 6, August 1998, Palo Alto, California.

I.Hadzic, Applying Reconfigurable Computing to Reconfigurable Networks, PhD, Thesis.

Principal Investigators:



Graduate Students:


Distributed Systems Laboratory
University of Pennsylvania
200 S. 33rd Street
Philadelphia, PA 19104