> Yeah, you sound like an equipment vendor whose main customers are incumbent > telco's in a few rich markets :-). You are right. My message was pretty much geared toward incumbents. But the majority of the access/aggregation is in their possessions, isn’t it? They typically have ducts that were huge for copper that is already extracted. One more fiber cable would be easy.
Agree that for competitive carriers DWDM would be more often needed. Even for competitive carriers, it makes sense to evaluate the cost to put fiber into the duct of incumbents. Especially because in some countries the price would be regulated. It would solve the problem forever – no need for the DWDM speed upgrade. I am calling to just not forget to evaluate this option too. Reminder: dark fiber is the best technical solution, for sure. Ed/ From: Mark Tinka [mailto:mark@tinka.africa] Sent: Wednesday, May 3, 2023 11:39 AM To: Vasilenko Eduard <vasilenko.edu...@huawei.com>; nanog@nanog.org Subject: Re: Routed optical networks On 5/3/23 08:20, Vasilenko Eduard wrote: I would risk to say a little more on this. Indeed, maybe the situation (in many countries) when the Carrier sells a lot of TDM services. But in general, packet services are enough these days for many carriers/regions. There aren't enough TDM services to warrant DWDM, nowadays. The reason for DWDM is mainly being driven by Ethernet, and IP. At any reasonable scale, it's actually pretty hard to buy a TDM service, in most markets. Additionally, I am sure that in many countries/Metro it is cheaper to lay down a new fiber than to provision DWDM, even if it is a pizza box. I disagree. Existing fibre may be cheap because it was laid down a decade or more ago, en masse, by several operators. So the market would be experiencing a glut, not because it is cheap to open up the roads and plant more fibre, but because there is so much of it to begin with. At worst, there is still enough duct space that the operator can blow more fibre. But when that duct gets full, and there are no more free ducts available, or another route needs to get built for whatever reason, it is a rather costly affair to open up the roads and trunk some fibre, in any market. So no, DWDM is not more expensive, if you are delivering services at scale. It is actually cheaper. It is only more expensive if you are small scale, because in some markets, the fibre glut means you can buy dark fibre for cheaper than you can light it with DWDM. But this is a situation unique to small operators, not large ones. The colored interface is still very expensive. This only matters for the line side. For client-facing, it's not a drama. And you typically buy more optics for the client side than you do the line side. Of course, there are some Cities (not “towns”) where it is very expensive or maybe even impossible to lay down a new fiber. Yes, in the majority of cases, it is cheaper to lay down fiber. I think what you mean to say is that in the majority of cases where there is fibre glut, and dark fibre is a market option, buying fibre is cheaper than lighting it with DWDM. This is true. But I think that on a global scale, this is the exception, not the rule. In general, you are not likely to be able to buy dark fibre, cheaply or otherwise, if you look at all markets in the world. Hence, the importance of DWDM for the Metro is overestimated. Again, only if you are small scale. If you are a large scale operator with as many IP/Ethernet customers as you have Transport, DWDM is essential. Use only routers. Provision enough fiber. Have always 1 router hop to the aggregation (hub-spoke topology), no routers chaining in the ring. If fiber is not enough – then use normal DWDM with an external transponder. Routers would be still in hub-spoke topology. Yeah, you sound like an equipment vendor whose main customers are incumbent telco's in a few rich markets :-). The life of the average operator, around the world, is far less glamorous. Mark.