Improving TCP Congestion Control over Networks with Heterogeneous Transmission Media

Tech ID: 10190 / UC Case 2000-353-0


Present internet applications are likely to operate over paths that either exhibit a high degree of asymmetry or appear asymmetric due to the significant load on the reverse data path. Under such conditions, the transmission control protocol (TCP) method of counting messages that acknowledge correctly received data (ACKs) results in significant underutilization of the link with higher capacity due to loss of ACKs on the slow link. In addition, ACK loss leads to outbursts of data traffic on the forward path. As a result, networks need an improved congestion control algorithm that is resilient to ACK loss. 

Technology Description

Scientists at the University of California, Santa Cruz have developed a new implementation of TCP that can detect  both the initial stages and the direction of congestion. After it determines if the congestion is developing in the forward path, it then isolates the forward throughput from events that may occur on the reverse path, such as congestion. TCP-Santa Cruz, as the method has been coined, presents major improvements over previous TCPs in the areas of congestion control and error recovery.


  • Communication networks: a method of improving congestion control of data packets transmitted over communication networks


  • Improved error-recovery strategy eliminates the need for Karn's algorithm and allows for timely and efficient retransmission of any lost packet
  • Ability to distinguish between variation due to increases or decreases in the forward or reverse paths of the connection
  • Provides an improved round trip time (RTT) estimate over traditional TCP approaches
  • Provides high throughput and low end-to-end delay and delay variance over networks with a simple bottleneck link, networks with congestion in the reverse path of the connection, and networks that exhibit path asymmetry
  • Eliminates oscillations in the congestion window while maintaining high link utilization
  • Achieves 99% link utilization in networks with path asymmetry

Patent Status

Country Type Number Dated Case
United States Of America Issued Patent 7,020,083 03/28/2006 2000-353


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  • Garcia-Luna-Aceves, Jose Joaquin(JJ

Other Information


Transmission Control Protocol, TCP, transmission media, Internet congestion, network congestion, communication networks, TCP-Santa Cruz, Cat3

Categorized As