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<DIV><FONT size=2> Studying scheduling algorithms(FQ, SFQ, RED, FRED,
REM, BRED, SRED) in IP networks, I got some questions that I cannot answer.
If you have any ideas on the following questions, please let me know the answers
or the pointers to related literature.</FONT></DIV>
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<DIV><FONT size=2>** Assumptions : We can reduce larger queuing delays caused by
huge router queue size by using several schemes.</FONT></DIV>
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<DIV><FONT size=2>1. Why do routers have small queue sizes?</FONT></DIV>
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<DIV><FONT size=2> Because TCP is a window-based congestion control scheme,
If routers provide small queue sizes such as 60 kbytes or 90 kbtytes, only up to
40 or 60 TCP connections can be buffered in a router queue. I think that we
should increase router queue sizes to support more TCP connections without TCP's
coarse retransmit timeout and to support high value of fairness because TCP's
VERY coarse timeout itself induces unfairness. Is there any technological
obstables for providing larger router queue sizes? To support thoudands of TCP
connections in core routers, I think that router should provide TCP
connections with several giga bytes queue sizes.</FONT></DIV>
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<DIV><FONT size=2>2. Why do researchers stress on Single FIFO scheduling schemes
such as RED?</FONT></DIV>
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<DIV><FONT size=2> If core routers can provide several giga bytes queue
size, why don't core routers use Fair Queuing schemes such as Fair Queuing and
Stochastic Fair Queuing? I think RED itself and its variant are far to
support minimum QoS such as fairness. RED is unscalable in that RED can't
prevent buffer overflows when there are many TCP connections. Although
SRED(Stabilized RED) solved this problem, I do not think that it can
protect TCP connections from unresponsive flows and can provide fairness even
when there are only TCP connections.</FONT></DIV>
<DIV><FONT size=2> I think that FQ should be implemented in routers, if
per-flow queuing can be implemented. Is there any technological obstables for
implementing per-flow queuing in high speed core routers?</FONT></DIV>
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<DIV><FONT size=2>Thanks in advance.</FONT></DIV>
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<DIV><BR>----------------------------------------------------------------------<BR> Cho,
Jeong-woo<BR> <BR> Communication and Information Systems
Laboratory<BR> Dept. of Electrical Engineering and Computer
Science<BR> Korea Advanced Institute of Science and
Technology(KAIST)<BR> 373-1 Kusong-dong, Yusong-gu, Taejon 305-701,
Korea<BR> <BR> TEL: +82-42-869-8067 (ex.107) FAX:
+82-42-867-0550<BR> E-mail: <A
href="mailto:ggumdol@comis.kaist.ac.kr">ggumdol@comis.kaist.ac.kr</A><BR>----------------------------------------------------------------------<BR></DIV></FONT></BODY></HTML>