Re: constant FEC errors juniper mpc10e 400g

[Mark Tinka <mark@tinka.africa>]

On 4/20/24 21:36, borg () uu3 net wrote:

> 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).

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.

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.

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.
> 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.

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).

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.

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.

Mark.