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<reference anchor='RFC0721'>

<front>
<title abbrev='Out-of-Band Control Signals'>Out-of-Band Control Signals in a Host-to-Host Protocol</title>
<author initials='L.' surname='Garlick' fullname='Larry Garlick'>
<organization>Stanford Research Institute (SRI) International, Augmentation Research Center (ARC)</organization></author>
<date month='September' day='1' year='1976' />
<abstract>
<t>This note addresses the problem of implementing a reliable out-of-band signal for use in a host-to-host protocol.  It is motivated by the fact that such a satisfactory mechanism does not exist in the Transmission Control Protocol (TCP) of Cerf et. al.,. In addition to discussing some requirements for such an out-of-band signal (interrupts) and the implications for the implementation of the requirements, a discussion of the problem for the TCP case will be presented.</t>
<t>While the ARPANET host-to-host protocol does not support reliable transmission of either data or controls, it does meet the other requirements we have for an out-of-band control signal and will be drawn upon to provide a solution for the TCP case.</t></abstract></front>

<seriesInfo name='RFC' value='721' />
</reference>
