RFC 1016 (rfc1016) - Page 1 of 18

Something a host could do with source quench: The Source Quench Introduced Delay (SQuID)

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Network Working Group                                            W. Prue
Request for Comments:  1016                                    J. Postel
                                                                     ISI
                                                               July 1987

             Something a Host Could Do with Source Quench:

               The Source Quench Introduced Delay (SQuID)

Status of this Memo

   This memo is intended to explore the issue of what a host could do
   with a source quench.  The proposal is for each source host IP module
   to introduce some delay between datagrams sent to the same
   destination host.  This is an "crazy idea paper" and discussion is
   essential.  Distribution of this memo is unlimited.

Introduction

   A gateway may discard Internet datagrams if it does not have the
   buffer space needed to queue the datagrams for output to the next
   network on the route to the destination network.  If a gateway
   discards a datagram, it may send a source quench message to the
   Internet source host of the datagram.  A destination host may also
   send a source quench message if datagrams arrive too fast to be
   processed.  The source quench message is a request to the host to cut
   back the rate at which it is sending traffic to the Internet
   destination.  The gateway may send a source quench message for every
   message that it discards.  On receipt of a source quench message, the
   source host should cut back the rate at which it is sending traffic
   to the specified destination until it no longer receives source
   quench messages from the gateway.  The source host can then gradually
   increase the rate at which it sends traffic to the destination until
   it again receives source quench messages [1,2].

   The gateway or host may send the source quench message when it
   approaches its capacity limit rather than waiting until the capacity
   is exceeded.  This means that the data datagram which triggered the
   source quench message may be delivered.

The SQuID Concept

   Suppose the IP module at the datagram source has a queue of datagrams
   to send, and the IP module has a parameter "D".  D is the introduced
   delay between sending datagrams from the queue to the network.  That
   is, when the IP module discovers a datagram waiting to be sent to the
   network, it sends it to the network then waits time D before even
   looking at the datagram queue again.  Normally, the value of D is



Prue & Postel
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