Speculative Traffic

Supporting prefetching/presending vs. direct transfers

Speculative use of bandwidth

Using speculation to reduce latency reduces the maximum bandwidth requirements as well. The max. BW reduces by 10-100x, although the link utilization goes up by 10x, i.e., the idle periods are used. The result is an overall reduction in the bandwidth requirements, with an increase in performance.

• E.g., fetch/send pages linked to the current page
• Required to support interactive use
  • Bandwidth required is very high, if no anticipation
  • Anticipation can reduce maximum bandwidth required by 10-100x
  • Use idle user-time for anticipation

Support prior to IntServ deployment

Speculation requires a user-settable "drop first" flag on packets, so that speculative traffic doesn't interfere with other, direct traffic. This can be deployed prior to Integrated Services deployment, using a mechanism currently under development at ISI.

• Back-off w.r.t., current TCP, UDP
• User-flagged low-priority

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