According to this graph : here is a full size version
The facebook AS32934 server in the US is direcly connected to DE-CIX in germany. How can that be possible ? Is there fibers over the ocean ?
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3I recommend learning what an autonomous system is; it's not a "server", and Facebook is large enough to actively manage physical presence and peering.– chrylis -cautiouslyoptimistic-Commented Apr 13, 2020 at 9:38
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2 Answers
Is there fibers over the ocean ?
They're more under the Ocean but absolutely, you can see a somewhat accurate map of them here. These undersea cables are how continents are interconnected and will usually have Tb/s worth of capacity. It's also important to note that AS32934 is not just a single Facebook Server but rather a whole Network full of Routers, Switches, Fibre & Servers.
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5It might be helpful to clarify that Facebook is, essentially, its own ISP, and it peers directly with other ISPs in the normal ways that ISPs do.– CarcerCommented Apr 13, 2020 at 11:16
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And Facebook probably doesn't have its own fibre. Facebook probably leases a certain wavelength from another company that does own a fibre. They might even lease a layer-2 or layer-3 VPN from a third company, which leases from a company that owns a fibre - I don't think that would show up in the AS connectivity graph? Commented Apr 13, 2020 at 11:29
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5@user253751, Facebook definitely own their own Fibre, in fact, they've been key building partners in a few undersea cables. See here: engineering.fb.com/connectivity/fiber-optic-cable Commented Apr 13, 2020 at 11:41
The facebook AS32934 server in the US is direcly connected to DE-CIX in germany. How can that be possible ? Is there fibers over the ocean ?
Note that this graph only shows IP routing. When a router in DE-CIX wants to send a packet to AS32934, it knows there is a link from DE-CIX to AS32934, so if it sends the packet out via that link, it will arrive at AS32934. It does not know what type of link it is.
It is likely that Facebook leases some kind of point-to-point VPN (or a real PN!) between one of their US server farms and DE-CIX. The VPN is not routed - traffic that comes in one end goes out the other end. So BGP doesn't need to know about it. At least, that's one possibility.
You'll also notice that this graph shows ASes, not servers. Roughly speaking, it shows which companies are connected to which other companies. Facebook is connected to DE-CIX. It doesn't tell you what part of Facebook is connected to DE-CIX. Facebook can have US servers and EU servers and some kind of connection between them - it's all included inside the box that says "Facebook". You wouldn't expect to see Facebook's internal connections here.
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1Facebook definitely own and build their own Fibre to connect their backbone, in fact, they've been key building partners in a few undersea cables. See here: engineering.fb.com/connectivity/fiber-optic-cable Commented Apr 13, 2020 at 11:42