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<p>Hallo Ramiro,</p>
<p><br></p>
<p>Freitag, 13. Juni 2008, meintest Du:</p>
<p><br></p>
<p><span class=rvts6>RAQ> On Fri, 2008-06-13 at 17:55 +0200, Jan Heichler wrote:</span></p>
<p><br></p>
<p><span class=rvts7>>> You can use the 24-port switches to create a full bisectional</span></p>
<p><span class=rvts7>>> bandwidth network if you want that. Since all the big switches are</span></p>
<p><span class=rvts7>>> based on the 24-port silicon this is no problem. </span></p>
<p><br></p>
<p><span class=rvts6>RAQ> Yes, But How many ports must I waste if I do not want to loose to much</span></p>
<p><span class=rvts6>RAQ> bandwidth.</span></p>
<p><br></p>
<p>Exactly 50%. 12 Ports go to clients and 12 ports go to the spine. I can send you a sketch if you are interested. </p>
<p><br></p>
<p><span class=rvts6>RAQ> And about latency, It could be negligible compared to latency at the</span></p>
<p><span class=rvts6>RAQ> infiniband card (~3 microsecs in front of 480 nanosecs at switch),</span></p>
<p><span class=rvts6>RAQ> right?</span></p>
<p><br></p>
<p>The number of HOPs is always the same... 3 up to 288 ports. With the new 36 port silicon that will change. Up to 648 Clients with 3 HOPs if i'm not wrong. </p>
<p><br></p>
<p><span class=rvts7>>> RAQ> c) Use the Flextronix 10U 144 Port Modular solution which will</span></p>
<p><span class=rvts7>>> allow us</span></p>
<p><br></p>
<p><span class=rvts7>>> RAQ> to scale well in a couple years</span></p>
<p><br></p>
<p><br></p>
<p><span class=rvts7>>> But you have to pay now for an expansion that you might never get...</span></p>
<p><span class=rvts7>>> Or want a fancy new network technology as soon as you upgrade.</span></p>
<p><br></p>
<p><span class=rvts6>RAQ> Well, I most probably will be needing 48 ports in five months and 120</span></p>
<p><span class=rvts6>RAQ> ports in about a year</span></p>
<p><br></p>
<p>48 Ports is 6 24 Port Switches. </p>
<p><br></p>
<p>here is a quick overview:</p>
<p><br></p>
<p>client ports #of 24 port switches you need for full bisectional bandwidth</p>
<p>24 1</p>
<p>36 5</p>
<p>48 6</p>
<p>60 8</p>
<p>72 9</p>
<p>84 11</p>
<p>96 12</p>
<p>108 14</p>
<p>120 15</p>
<p>132 16</p>
<p>144 18</p>
<p><br></p>
<p>Somewhere around 11 and 14 is normally the break even for a 144-port switch - depends on your cost prices of course ;-)</p>
<p><br></p>
<p>I hope i didn't miscalculate ;-)</p>
<p><br></p>
<p><span class=rvts6>RAQ> Thanks for your answer</span></p>
<p><br></p>
<p>Any time!</p>
<p><br></p>
<p>Regards, Jan </p>
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