Paper review: < TCP Vegas: End to End Congestion Avoidance on a Global Internet [BP95] >

Reviewer: <Ryan Gehl>

  1. State the problem the paper is trying to solve.
  2. The purpose of this paper is to describe another implementation of TCP (Vegas) that has 37 to 71% higher throughput on the Internet than the current distribution (Reno) of BSD Unix.

  3. State the main contribution of the paper: solving a new problem, proposing a new algorithm, or presenting a new evaluation (analysis). If a new problem, why was the problem important? Is the problem still important today? Will the problem be important tomorrow?  If a new algorithm or new evaluation (analysis), what are the improvements over previous algorithms or evaluations? How do they come up with the new algorithm or evaluation? 
  4. The main contribution of this paper is to concretely describe a new implementation of TCP.

  5. Summarize the (at most) 3 key main ideas (each in 1 sentence.) 
  6. 1) The Vegas implementation does not involve any changes to the TCP specification, as all of the changes are confined to the sending side.
    2) The improvement in throughput is not achieved by an aggressive retransmission strategy that effectively steals bandwidth away from TCP connections that use the Reno implementation. Rather, it is achieved by a more efficient use of the available bandwidth.
    3) The three new techniques implemented in Vegas are (1) a new retransmission mechanism, (2) a congestion avoidance mechanism, and (3) a modified slow-start mechanism.

  7. Critique the main contribution
  8. What lessons should researchers and builders take away from this work. What (if any) questions does this work leave open?

One lesson researchers should take away from this work is that it is often possible to improve upon existing implementations of a given protocol without having to modify the protocol itself.