Cisco Optics Podcast Ep 57. The smartest data center operators use multi-mode fiber - do you? (6/7)

[00:00:09] Hello everyone and welcome back to the Cisco Optics Podcast where we talk about pluggable optics for networks. Multi-mode fiber has been the workhorse for fiber optic communication within a data center for years, as well as a choice for ethernet

[00:00:21] backbones and office buildings. It has a rich history that goes all the way back to the first optical fiber standards when 100 megabits per second was a huge data rate. Anybody remember those days? This is episode 57 and we continue our conversation with Hao Dong, Market Technology Development Manager for

[00:00:40] Corning's Optical Communications Business. We get into the reach of future high-speed standards for multi-mode fiber. Hao Dong is a Market Technology Development Manager for Corning's Optical Communications Business. Within this role he focuses on technology and market trends to identify, evaluate, and develop leading

[00:00:59] optical network solutions that form the backbone of today's connected world. Hao has over 18 years of industry experience and has held various positions in engineering, development, and marketing within the fields of optical components, fiber lasers, and optical communications.

[00:01:14] Hao holds a Bachelor of Science in Physics from Wuhan University and a PhD in Physics from the University of Connecticut. One quick note before we start. You'll hear Hao mention a 100 meter reach fiber that they're working on. Since we recorded this, Corning has

[00:01:27] launched that fiber. It's their clear curve OM3XT and OM4XT multi-mode fiber. And now join me as I talk with Hao Dong. But the problem is that for this newly defined IEEE standards, the OM3 is no longer supporting 70 meter. It only supports the distance up to

[00:01:57] 60 meter. But again for OM4 it's still supported 100 meter. Do you know why it's 60 and not 70? Was there a debate about that? So basically if you look at the, you know, if you go back to the basics, right, what is really limiting the distance? What is really limiting the

[00:02:22] transmission capability? So I think there is a way to define it, which is the link bandwidth. So for if you follow the link bandwidth approach and do some calculation you will see the OM3 fiber ENB will not be able to

[00:02:46] support 70 meter. So you have to take the compromise and that's a fundamental reason for this 60 meter versus 70 meter discussion. In other words, the fiber bandwidth, the fiber ENB is not higher enough to support 70 meter at this case. So after all the analysis it just

[00:03:12] I'm sure people would have wanted it to support 70 if possible so that we there can be a consistent spec from generation to generation but you're saying after all the analysis it was concluded it's just not

[00:03:24] feasible? Exactly, exactly. Yeah this is a you know big problem for the 100G per LAN so you know almost for the first time right the fiber bandwidth becomes a bottleneck. As we said again 70 meter on 3 and 100 meter on 4 that's a golden

[00:03:46] roll but it seems like it has to be bridged in this case. And you know it's not only for we talk about the 100G per LAN being treated as a future proofing solution. So there are another

[00:04:00] effort ongoing as well which is BiDi. So you know there is a 100G per LAN based BiDi MSA which is called the terabit BiDi. Terabit BiDi defines you know defines the transmission reach spec as it's even shorter. So for OM3

[00:04:22] it only supports 45 meter and OM4 only supports 70 meters. So from you know from both that's also 100G per LAN? That's also 100G per LAN yeah that's also 100G per LAN but the difference is BiDi. So yeah so that's a problem we see and you know

[00:04:46] from the fiber standpoint obviously the question is how do we address the issue right? So currently you know we're working on the new fiber trying to hopefully we you know we can address this issue and deliver a longer distance than

[00:05:05] just you know generic OM3 and OM4. Okay is there anything else you want to bring up? Any current work that you've been doing? Anything you've been thinking about a lot lately? Yeah you mentioned the application for multimode right so obviously I think

[00:05:29] the big topic of people are thinking will be where the multimode fiber will be used. So I think obviously data center is a good application space especially in North America I think the enterprise data center these guys are still they love multimode right they're still

[00:05:49] a lot multimode being deployed for data center applications and also in another application case or application space for multimode will be China clouds so I think you know if you compare the China clouds company versus the hyperscale in North America you will see the difference in terms

[00:06:12] footprint right. So in North America the hyperscale DC typically really spread out the campus over a size or footprint of stadium right it's huge yeah the China clouds okay good yeah typically China clouds you know those data center

[00:06:34] located in multi-story buildings so in terms of the footprint is smaller so that's why they still think you know 100 meter is good enough to to finish their say leaf to spine interconnections.

[00:06:48] That's interesting I never knew about that. Yeah yeah we heard a lot about that especially you know when it comes to the single-mode versus the multimode discussion I think it's widely believed that

[00:07:03] big clouds in China will deploy a large volume of 200g 400g multimode solution in the next a couple years so yeah. Do you know if they have a preference for OM3 OM4 maybe special fiber? OM3 yeah OM3 will be the dominant fiber option for that really

[00:07:28] for most of the applications for China clouds yes because even even have a strong preference even at you know one of these two new standards either the IEEE or the Terabit for the single line

[00:07:43] 100 gig. Well for the status quo I think they prefer the OM3 because of the cost of consideration that you know the fiber cost on OM3 is obviously it's cheaper than OM4 right but when it comes to

[00:07:58] the future proofing solution say 100G per land so I think a lot of things are still to be determined but yeah definitely there will be a you know there will be the reach the distance will be a

[00:08:12] consideration. Yeah so I guess the question is can can they let's say they go with the IEEE can they accommodate 60 meters instead of 70 right? Is that going to be a problem?

[00:08:27] That could be a problem so that's a problem we are considering as well so that's why like I said you know we are working on the new 100G per land based of fiber trying to address

[00:08:43] the rich issues in 100G per land based application including the biodi namely the Terabit biodi and also 100G IEEE AO2-3DTB define the transceivers so with the you know with the newer fiber EMB specification the higher EMB specification especially you know the EMB

[00:09:10] yeah B values at the 910 nanometer they will address the rich issue for for terabit biodi application. Okay well sounds exciting. Yeah oh by the way the other application I think a big application for multimode potentially could be the you know AI machine learning applications right so we

[00:09:41] you know these days people talk a lot about fiber to the machine fiber to the server and the server right so that's another application space with a lot of potentials. Okay so basically replacing what's currently like top of rock switch to server connectivity which is basically copper

[00:10:01] cables still. That was the sixth part of my conversation with Howdong next time we'll continue with the reach of high-speed standards from multimode fiber and the impact on data center deployments. We have a new website it's optics.podcastpage.io you can either listen there

[00:10:28] or use the same podcast platform you've been using all along please subscribe better yet leave a review especially if you've been using Apple podcast remember we're part of the Cisco podcast network where you can find other great Cisco podcasts too we also have

[00:10:44] educational videos on YouTube just go to youtube.com and search on Cisco optics thank you for listening this is Pat Child product manager at Cisco optics the next episode is the seventh and final part of my conversation with Howdong until next time