Issues in TCP Slow-Start Restart After Idle

Document Type Expired Internet-Draft (tcpimpl WG)
Authors Joseph Touch  , John Heidemann  , Amy Hughes 
Last updated 1998-04-10
Stream IETF
Intended RFC status (None)
Expired & archived
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Stream WG state WG Document
Document shepherd No shepherd assigned
IESG IESG state Expired
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This Internet-Draft is no longer active. A copy of the expired Internet-Draft can be found at


This draft discusses variations in the TCP 'slow-start restart' (SSR) algorithm, and the unintended failure of some variations to properly restart in some environments. SSR is intended to avoid line-rate bursts after idle periods, where TCP accumulates permission to send in the form of ACKs, but does not consume that permission immediately. SSR's original 'restart after send is idle' is commonly implemented as 'restart after receive is idle'. The latter unintentionally fails to restart for bidirectional connections where the sender's burst is triggered by a reverse-path data packet, such as in persistent HTTP. Both the former and latter are shown to permit bursts in other circumstances. Three solutions are discussed, and their implementations evaluated. This document is a product of the LSAM project at ISI. Comments are solicited and should be addressed to the authors.


Joseph Touch (
John Heidemann (
Amy Hughes (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)