You are right, my “Metro” definition is about ISP/Carriers.

Mobile or Fixed, despite pure Mobiles would like to call it MBH – it has much less traffic (Mobile subscribers would always have 7x less than fixed).

It is still the place where the majority of port capacity lives. Because all content and cache are after this link.

50GE is better just because it is half of the cost of 100GE and it is enough now for the great majority of cases. Money is very important these days for this industry. 100GE single mode is more expensive than the best router port itself. Routers have been deprecated 10x for the decade (almost 100x for 2 decades). Pluggable optics is not that much deprecated.

I do not think that content provider guys call their DCI “Metro”, not very often.

I agree that 100GE for DCI is the minimum, 400GE is probably already needed in some places.

IMHO: it is a different story. Very interested too.

PS: By the way, even if some ISP has 50% of revenue from Enterprise services (it is probably the biggest number, typically 30%-40%), it is still just 5% compare to residential traffic. Traffic to enterprises is still sold 4x-10x (depending on the country).

Hence, Enterprise does not make sense to mention in the traffic discussion. It is a “rounding error”.

Enterprise business created a huge demand for oversubscribed ports to connect Enterprises. And QoS/QoE. Not traffic.

Eduard

From: NANOG [mailto:nanog-bounces+vasilenko.eduard=huawei.com@nanog.org] On Behalf Of Mark Tinka
Sent: Friday, May 5, 2023 11:13 AM
To: nanog@nanog.org
Subject: Re: Routed optical networks

On 5/5/23 07:57, Vasilenko Eduard via NANOG wrote:

Disclaimer: Metaverse has not changed Metro traffic yet. Then …

I am puzzled when people talk about 400GE and Tbps in the Mero context.

For historical reasons, Metro is still about 2*2*10GE (one “2” for redundancy, another “2” for capacity) in the majority of cases worldwide.

How many BRASes serve more than 40000/1.5=27k users in the busy hour?

It means that 50GE is the best interface now for the majority of cases. 2*50GE=100Gbps is good room for growth.

Of course, exceptions could be. I know BRAS that handles 86k subscribers (do not recommend anybody to push the limits – it was so painful).

We have just 2 eyes and look at video content about 22h per week (on average). Our eyes do not permit us to see resolution better than particular for chosen distance (4k for typical TV, HD for smartphones, and so on). Color depth 10bits is enough for the majority, 12bits is sure enough for everybody. 120 frames/sec is enough for everybody. It would never change – it is our genetics.

Fortunately for Carriers, the traffic has a limit. You have probably seen that every year traffic growth % is decreasing. The Internet is stabilizing and approaching the plateau.

How much growth is still awaiting us? 1.5? 1.4? It needs separate research. The result would be tailored for whom would pay for the research.

IMHO: It is not mandatory that 100GE would become massive in the metro. (I know that 100GE is already massive in the DC CLOS)

Additionally, who would pay for this traffic growth? It also limits traffic at some point.

I hope it would happen after we would get our 22h/4k/12bit/120hz.

Now, you could argue that Metaverse would jump and multiply traffic by an additional 2x or 3x. Then 400GE may be needed.

Sorry, but it is speculation yet. It is not a trend like the current (declining) traffic growth.

So, it depends on what "metro" means to you.

For an ISP selling connectivity to enterprise customers, it can be a bunch of Metro-E routers deployed in various commercial buildings within a city. For a content provider, it could be DCI. For a telco, it could interconnecting their Active-E/GPON/DSLAM/CMTS network.

Whatever the case, the need for 100Gbps is going to be driven by the cost of optics over the distance required. Some operators run 2x 10Gbps for resilience/redundancy, while some others run 4x 10Gbps for the same. It all depends on the platform you are using. At some point, that capacity runs out, especially when you account for fibre outages, and you need something larger on one side of the ring mainly to provide sufficient bandwidth during failure events on the other side of the ring, and not necessarily because you are growing by that much.

Also, if the optics are available and are reasonably priced, why muck around with 40Gbps when you can just go straight to 100Gbps? The equipment usually can support either.

I'm unaware of any popularity around 50Gbps interfaces, but I also probably don't pay too much attention to such nuance :-).

So, it's not that we are seeing organic growth that justifies 100Gbps over anything smaller. It's more that the optics are available, they are cheap, they can go the distance, and the routers/switches can do the speed. At least, for us anyway, that is what is driving the next phase of our Metro-E network... going straight from 10Gbps to 100Gbps links, not because that is the growth we are seeing from an organic traffic standpoint, but because the routers can do it, and it offers us peace of mind that we can handle any traffic re-route when one half of the ring fails, without dropping packets.

The 400Gbps market will be restricted to mainly content folk linking up data centres, as well as some large telco's, for the time being. It is not likely to be the norm for the majority of operators who run some kind of metro network.

Mark.