Draft: draft-ietf-quic-manageability

Commentary: Using the Spin Bit for Passive RTT Measurement ... Note that this measurement , as with passive RTT measurement for TCP , includes any transport protocol delay ( e.g. , delayed sending of [ acm ] suggest s / any / all/ ... Since the spin bit logic at each endpoint considers only samples from packets that advance the largest packet number , signal generation itself is resistant to reordering . However , reordering can cause problems at an observer by causing spurious edge detection and therefore inaccurate ( i.e. , lower ) RTT estimates , if reordering occurs across a spin - bit flip in the stream . [ acm ] thanks for mentioning this ! ... Raw RTT samples generated using these techniques can be processed in various ways to generate useful network performance metrics . A simple linear smoothing or moving minimum filter can be applied to the stream of RTT samples to get a more stable estimate of application - experienced RTT . RTT samples measured from the spin bit can also be used to generate RTT distribution information , including minimum RTT ( which approximates network RTT over longer time windows ) and RTT variance ( which approximates jitter as seen by the application ) . [ acm ] ( let 's avoid the clocky term " jitter " , and clarify ) Suggest : ( which over - estimates one - way packet delay variance as seen by an application end - point ) .
Paragraph (version A):
Handshake RTT can be measured by adding the client-to-observer and
observer-to-server RTT components together.  This measurement
necessarily includes any transport- and application-layer delay at
both endpoints.
Paragraph (version B):
Handshake RTT can be measured by adding the client-to-observer and
observer-to-server RTT components together.  This measurement
necessarily includes all transport- and application-layer delay at
both endpoints.
Paragraph (version A):
Note that this measurement, as with passive RTT measurement for TCP,
includes any transport protocol delay (e.g., delayed sending of
acknowledgments) and/or application layer delay (e.g., waiting for a
response to be generated).  It therefore provides devices on path a
good instantaneous estimate of the RTT as experienced by the
application.
Paragraph (version B):
Note that this measurement, as with passive RTT measurement for TCP,
includes all transport protocol delay (e.g., delayed sending of
acknowledgments) and/or application layer delay (e.g., waiting for a
response to be generated).  It therefore provides devices on path a
good instantaneous estimate of the RTT as experienced by the
application.
Paragraph (version A):
Raw RTT samples generated using these techniques can be processed in
various ways to generate useful network performance metrics.  A
simple linear smoothing or moving minimum filter can be applied to
the stream of RTT samples to get a more stable estimate of
application-experienced RTT.  RTT samples measured from the spin bit
can also be used to generate RTT distribution information, including
minimum RTT (which approximates network RTT over longer time windows)
and RTT variance (which approximates jitter as seen by the
application).
Paragraph (version B):
Raw RTT samples generated using these techniques can be processed in
various ways to generate useful network performance metrics.  A
simple linear smoothing or moving minimum filter can be applied to
the stream of RTT samples to get a more stable estimate of
application-experienced RTT.  RTT samples measured from the spin bit
can also be used to generate RTT distribution information, including
minimum RTT (which approximates network RTT over longer time windows)
and RTT variance (which approximates one-way packet delay variance as
seen by an application end-point).