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<p><span style="color: rgb(34, 34, 34); font-family: arial,
sans-serif; font-size: 12.8px; font-style: normal; font-variant:
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display: inline !important; float: none; background-color:
rgb(255, 255, 255);"></span>one of my clients asked arista about
bufferbloat issues in their switches. here was their response.
is their analysis right?<br style="color: rgb(34, 34, 34);
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background-color: rgb(255, 255, 255);"><font size="2">------<br>
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<span style="font-family: arial, helvetica, sans-serif;">Buffer
bloat was a relevant on 10/100M switches, not 10Gb switches.
At 10Gb we can empty the queue in ~100ms, which is less than
the TCP retransmission timers, therefore no bloat. Buffer
bloat can happen at slower speeds, but not an issue at the
speeds we have on our switches.<span
class="Apple-converted-space"> </span></span></font><br>
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</span></font></div>
<font size="2"><span style="font-family: arial, helvetica,
sans-serif;">There are some articles regarding bufferbloat
on the net, but buffer bloat is not a problem on our
switches. Some of the information regarding bufferbloat
sites Internet routers where packets can be held in queues
of very large buffers for several seconds, up to 10
seconds which can cause TCP retransmission problems and
lower overall application performance when going across
the public Internet.</span></font>
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<p style="color: rgb(34, 34, 34); line-height: normal;"><font
size="2"><span style="font-family: arial, helvetica,
sans-serif;">The buffers on the Arista 7500 are 128MB
of packet buffers per 10GbE port coupled to a fully
arbitrated (VOQ) virtual output queue forwarding
system. At 10Gbps this is ~100msec of buffer capacity
which is an order of magnitude from ‘1 second’ and 2
orders of magnitude from the 10 seconds worst case
identified in buffer bloat documents.<br>
</span></font></p>
<p style="color: rgb(34, 34, 34); line-height: normal;"><font
size="2"><span style="font-family: arial, helvetica,
sans-serif;">We (Arista) have switching systems with
large buffers and high port count, or low buffers and
high port count running one operating system. Buffer
bloat is real in systems that would have more than
1.25GB of packet buffer per 10Gb port - none of these
systems contribute to the buffer bloat issue.</span></font></p>
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<font size="2"><span style="font-family: arial, helvetica,
sans-serif;">We position deep buffering switches where<span
class="Apple-converted-space"> </span><span
style="color: rgb(0, 0, 0); font-weight: 400;
font-style: normal; font-variant: normal;
text-decoration: none; vertical-align: baseline;
background-color: transparent;">lossless performance is
necessary. <span class="Apple-converted-space"> </span></span></span></font></div>
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