<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Mark,<br><br>Thanks for your suggestion. I got this book and read through the queueing and scheduling parts of it. This helps but most of my question still remains.<br><br>In Chapter 10 of the book, the idea of dual arbitrator makes sense but it would not be so clear when we have H-Qos and have more than one SAP defined on the same port, or have multiple tier-1 schedulers defined on the same SAP.<br><br>In Chapter 11 of this book, the arbitrator idea is not mentioned anymore.. It is assumed that the root scheduler already have the "Obtained bandwidth" but it is not clear to me how the "obtained bandwidth" is calculated. Does this depend on the CIR/PIR defined on the scheduler, or simply by dividing the total BW on the port by the number of tier 1 schedulers, or even other more complex method? I believe the actual schedulers does not divide the bandwidth first
then schedule the packets, but rather the BW is the effective value of the result of scheduling. It is very clear to everybody that how the tier one will select a packet from all its child queues when it is allowed to transmit, but it is totally black (for me at least) how the actual port selects which tier 1 scheduler to send next.<br>From the previous response from Diego it seems this is again back to the arbitrator, but if anyone knows any more details it would be very nice, since I'm not too confident to deploy this without knowing more details..<br><br>thanks,<br>Kila<br><br>--- On <b>Thu, 2/19/09, Mark Griffin <i><Mark.Griffin@hawaiiantel.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;">From: Mark Griffin <Mark.Griffin@hawaiiantel.com><br>Subject: RE: [alcatel-nsp] Question about Service QoS Policies on 7750SR<br>To: hsukila@yahoo.com, alcatel-nsp@puck.nether.net,
"GARCIA DEL RIO Diego" <Diego.Garcia_Del_Rio@alcatel-lucent.be><br>Date: Thursday, February 19, 2009, 7:00 PM<br><br><div id="yiv713432732">
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<p class="MsoNormal"><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Kila, do you have Ram’s book “Advance
QoS for Multi-service IP/MPLS Networks”? His book does a good job
of explaining the behavior of traffic conditioning in the hierarchal model.</span></font></p>
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<p class="MsoNormal"><b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma;">
alcatel-nsp-bounces@puck.nether.net
[mailto:alcatel-nsp-bounces@puck.nether.net] <b><span style="font-weight: bold;">On
Behalf Of </span></b>Kila Hsu<br>
<b><span style="font-weight: bold;">Sent:</span></b> Thursday, February 19, 2009
12:44 PM<br>
<b><span style="font-weight: bold;">To:</span></b> alcatel-nsp@puck.nether.net;
GARCIA DEL RIO Diego<br>
<b><span style="font-weight: bold;">Subject:</span></b> Re: [alcatel-nsp]
Question about Service QoS Policies on 7750SR</span></font></p>
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<p class="MsoNormal"><font size="3" face="Times New Roman"><span style="font-size: 12pt;">Thanks a lot, Diego!<br>
<br>
I still have several question though. Assume that we don't have a port
scheduler defined, and we do get congestion. As you mentioned, now queues are
transmitted at the physical level using round robin, with expedited queues
being served first.<br>
<br>
1. By "queues" do you mean the queue-to-be-transmitted for each
SAP? If there are multiple tier 1 schedulers, or orphaned queues in a SAP,
which one will get transmitted? (or will these queues now become the
candidates for the physical level round-robin?)<br>
<br>
2. How are the weights assigned for all these queues? Or is this just an
plain old round-robin with every queue equally weighted?<br>
<br>
3. If under each SAP I have hierarchical scheduler, it is possible that for
one SAP, the next packet to be sent comes from an best-effort queue but the
next-next one comes from an expedited queue (although this is a bad design).
In this case, will this SAP have to wait in the physical level until the
expedite queues from other SAPs are transmitted?<br>
<br>
I hope I state the problems clearly. Thanks again for all who kindly answer!<br>
<br>
Best Regards,<br>
Kila Hsu<br>
<br>
--- On <b><span style="font-weight: bold;">Mon, 2/16/09, GARCIA
DEL RIO Diego
<i><span style="font-style: italic;"><Diego.Garcia_Del_Rio@alcatel-lucent.be></span></i></span></b>
wrote:</span></font></p>
<p class="MsoNormal" style="margin-bottom: 12pt;"><font size="3" face="Times New Roman"><span style="font-size: 12pt;">From: GARCIA DEL RIO
Diego <Diego.Garcia_Del_Rio@alcatel-lucent.be><br>
Subject: Re: [alcatel-nsp] Question about Service QoS Policies on 7750SR<br>
To: alcatel-nsp@puck.nether.net<br>
Date: Monday, February 16, 2009, 1:15 PM</span></font></p>
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<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Hi Hsu,</span></font></p>
<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;"> </span></font></p>
<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">
If your version of TiMOS allows it, you could run a “port-parent”
scheduler, which allows you to map the parent scheduler of the queues in the
SAPs to a port-level scheduler that will distribute bandwidth between all it’s
children according to the configured prioritied.</span></font></p>
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<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">
If you don’t have the port-schduler function (it appeared in TiMOS
5.0r4 and onwards), sap-queues and schedulers behave “as
expected” when there is no congestion at the port level, that is, all
egressing traffic is less than the port’s egress rate.</span></font></p>
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<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">
If there is congestion though, and no port-scheduler is configured, queues
are indeed served in round-robin fashion with the “expedited”
queues (in in-profile state) being served exhaustively, then
“best-effort” (in-profile) and finally all out-of-profile queues.</span></font></p>
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<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">
So.. in short, if using TiMOS 5.0 or newer, take a look at port-level
schedulers ;-)</span></font></p>
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<p class="MsoNormal" style=""><font color="navy" size="2" face="Arial"><span style="font-size: 10pt; font-family: Arial; color: navy;">Cheers!</span></font></p>
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<p class="MsoNormal" style=""><b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma; font-weight: bold;">From:</span></font></b><font size="2" face="Tahoma"><span style="font-size: 10pt; font-family: Tahoma;">
alcatel-nsp-bounces@puck.nether.net
[mailto:alcatel-nsp-bounces@puck.nether.net] <b><span style="font-weight: bold;">On Behalf Of </span></b>Kila Hsu<br>
<b><span style="font-weight: bold;">Sent:</span></b> 16 February 2009 16:46<br>
<b><span style="font-weight: bold;">To:</span></b> alcatel-nsp@puck.nether.net<br>
<b><span style="font-weight: bold;">Subject:</span></b> Re: [alcatel-nsp] Question
about Service QoS Policies on 7750SR</span></font></p>
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<p class="MsoNormal" style=""><font size="3" face="Times New Roman"><span style="font-size: 12pt;">Hi,<br>
Thanks a lot to Mark for the information about the ways to share a port
among SAPs.<br>
However, my boss seems to like the idea that each SAP can have its own
queues and schedulers though..<br>
So say if I still need to deploy QoS on a per-SAP base, anyone know how the
packets from different SAPs defined on a common port would be scheduled, if
each has its own queue/scheduler?<br>
From the config guide I do see the "expedite" setting have
something to do with "hardware scheduler", but it is not clear if
the setting is used in cases like this.<br>
Any idea would be appreciated.<br>
<br>
thanks,<br>
Kila Hsu</span></font></p>
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<pre><font size="2" face="Courier New"><span style="font-size: 10pt;">_______________________________________________<br><br>alcatel-nsp mailing list<br><br>alcatel-nsp@puck.nether.net<br><br>https://puck.nether.net/mailman/listinfo/alcatel-nsp</span></font></pre></td>
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