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<DIV><FONT size=2 face=Arial>Sahil.,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Codel tries to address the problems that RED
couldn't; First, the input signal into the algorithm (sojourn time vs. average
queue depth) is of a different quality; Second, Codel (in it's plain form)
does drop/mark on dequeue, while RED drops/marks on enqueue.
This means, that [TCP] congestion control loop is much quicker with Codel
over RED; thus the reaction by the sender will probably be timely and relevant
for that congestion epoch. With RED; the congestion signal (that lost
packet) has to traverse the filled-up buffer first, thus the control loop time
is much larger (includes the instantaneous queue length of the buffer) - and is
further delayed by the averaging going on.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Codel, by design, doesn't need to be tuned
specifically for one particular drain rate (bandwidht) of the queue - unlike
RED; So it adjusts much better to variable bandwidth MACs (Wifi,
DOCSIS).</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>I've been told, that RED is easier to implement in
HW due to that action being all done on enqueue. With PIE, there exists another
AQM that tries to re-use the hw engines that exist for RED, but the control
algorithms try to use a different input signal - making the best of
that.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>If you follow the AQM work in IETF, there is strong
consensus steer to these more modern AQMs.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Best regards,</FONT></DIV>
<DIV><FONT size=2 face=Arial> Richard</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=sahilgrover013@gmail.com href="mailto:sahilgrover013@gmail.com">sahil
grover</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=chromatix99@gmail.com
href="mailto:chromatix99@gmail.com">Jonathan Morton</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A title=codel@lists.bufferbloat.net
href="mailto:codel@lists.bufferbloat.net">codel@lists.bufferbloat.net</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, February 24, 2015 5:20
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Codel] why RED is not
considered as a solution to bufferbloat.</DIV>
<DIV><BR></DIV>
<DIV dir=ltr>So we can say Codel is better than other AQM???</DIV>
<DIV class=gmail_extra><BR>
<DIV class=gmail_quote>On Tue, Feb 24, 2015 at 9:24 PM, Jonathan Morton <SPAN
dir=ltr><<A href="mailto:chromatix99@gmail.com"
target=_blank>chromatix99@gmail.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>
<P dir=ltr>Simply put, RED is a very old algorithm, one of the first viable
AQM algorithms. However, it proved to be so difficult to configure properly
that almost nobody uses it, even though many carrier grade routers implement
it.</P>
<P dir=ltr>Codel not only performs better than an ideally configured RED,
but is far easier to configure. This makes it much more deployable.</P><SPAN
class=HOEnZb><FONT color=#888888>
<P dir=ltr>- Jonathan
Morton<BR></P></FONT></SPAN></BLOCKQUOTE></DIV><BR></DIV>
<P>
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