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<div class="moz-cite-prefix">On 4/20/24 21:36, <a
class="moz-txt-link-abbreviated moz-txt-link-freetext"
href="mailto:borg@uu3.net" moz-do-not-send="true">borg@uu3.net</a>
wrote:<br>
<br>
</div>
<blockquote type="cite"
cite="mid:Pine.LNX.4.64.2404202131190.23323@cube">
<pre class="moz-quote-pre" wrap="">Erm, WAN-PHY did not extend into 40G because there was not much
of those STM-256 deployment? (or customers didnt wanted to pay for those).</pre>
</blockquote>
<br>
With SONET/SDH, as the traffic rate increased, so did the number of
overhead bytes. With every iteration of the data rate, the overhead
bytes quadrupled. This was one of the key reasons we did not see
field deployment of STM-256/OC-768 and STM-1024/OC-3072. For
example, if SONET/SDH had to transport a 100G service, it would
require 160Gbps of bandwidth. That clearly wasn't going to work.<br>
<br>
At the time when STM-256/OC-768 was being developed, DWDM and OTN
had come a long way. The granularity SONET/SDH required to stand up
a service had become too small for the growing data rate (primarily
VC-3, VC-4 and VC-12). If you look at OTN, the smallest container is
1.25Gbps (ODU0), which was attractive for networks looking to
migrate from E1's, E3's, STM-1's, STM-4's and STM-16's - carried
over VC-12, VC-4 and VC-3 SDH circuits - to 1GE, for example, rather
than trying to keep their PDH/SDH infrastructure going.<br>
<br>
DWDM and OTN permitted a very small control overhead, so as data
rates increased, there wasn't the same penalty you got with
SONET/SDH.<br>
<span style="white-space: pre-wrap">
</span><span style="white-space: pre-wrap">
</span>
<blockquote type="cite"
cite="mid:Pine.LNX.4.64.2404202131190.23323@cube">
<pre class="moz-quote-pre" wrap="">WAN-PHY was designed so people could encapsulate Ethernet frames
right into STM-64. Once world moved out of SDH/SONET stuff, there was
no more need for WAN-PHY anymore.</pre>
</blockquote>
<br>
Technically, what you are describing is EoS (Ethernet over SONET,
Ethernet over SDH), which is not the same as WAN-PHY (although the
working groups that developed these nearly confused each other in
the process, ANSI/ITU for the former vs. IEEE for the latter).<br>
<br>
WAN-PHY was developed to be operated across multiple vendors over
different media... SONET/SDH, DWDM, IP/MPLS/Ethernet devices and
even dark fibre. The goal of WAN-PHY was to deliver a low-cost
Ethernet interface that was SONET/SDH-compatible, as EoS interfaces
were too costly for operators and their customers.<br>
<br>
As we saw in real life, 10GE ports out-sold STM-64/OC-192 ports, as
networks replaced SONET/SDH backbones with DWDM and OTN.<br>
<br>
Mark.<br>
<br>
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