Google Buys a Piece of a Cable To Japan

Googling Yourself writes "Google announced that they will be part of a six-company consortium that will build a high-bandwidth sub-sea fiber optic cable linking the US and Japan. The new cable system, named Unity, is expected initially to increase Trans-Pacific lit cable capacity by about 20 percent, with the potential to add up to 7.68 Terabits per second of bandwidth across the Pacific. The name Unity was chosen to signify a new type of consortium, born out of potentially competing systems, to emerge as a system within a system, offering ownership and management of individual fiber pairs. Rumors that Google would join the consortium had originally surfaced in September last year but the company had declined to confirm or deny the news."

Comments

how many strands

[seanadams.com]

in such a cable?

And how do you figure out the optimal capacity to install anyway? To me 7 Tbits does not sounds like much to link two whole countries. Surely there is some point of diminishing returns, but why not more than this?

Re:how many strands

[OeLeWaPpErKe]

Actually you might want to look up DWDM and CWDM. It really depends on the cable, but even with systems commercially available (if a bit pricey) today, you can do up to 80 channels on a single fiber strand, allowing for 800 Gbit per fiber line (half duplex), which means you can achieve 800 Gbit per fiber pair full duplex.

This obviously depends on a lot of things, the most important parts are the retransmission stations on the cable (every 50 km or so), as they're very hard, and VERY expensive to replace. Generally half the fiber strands are backups, and all cables connect only to either even or uneven retransmission stations, allowing the cable to keep functioning with the loss of any one retransmission station (a frequent occurance). Problem is that for repairs a ship needs to come by, retrieve 3 transmission stations from their 200 meter depths, and get engineers close enough to conduct repairs, while preventing other ships from crossing the exposed 200-or-so kilometer of exposed cable. This is one of those ships.

Btw these retransmission stations are sinking pods that "float" below the ocean at a given depth (generally 200 meters or so). They are powered by a high voltage current transmission system in the cable itself.

Wikipedia entry on WDM

Re:Good news all around if it happens

[kitsunewarlock]

My globe just shrunk a little bit more.

They sell a creme for that.

Re:Good news all around if it happens

[totally bogus dude]

I don't think it will have much, if any, effect on Australia. Most of the focus of our ISPs is getting to the West coast of North America, and going via Japan is a pretty significant detour. Mind you, the Australia-Japan Cable gives us 320 Gbit/sec to Japan.

A trace from a server in Ohio to 72.14.235.104 (one of google.co.jp's addresses) has a RTT of 200 ms, which is about the same as the East coast of Australia to www.google.com (I get 230 ms from Perth). So for US-based sites going via this new cable would, I imagine, be quite a bit slower than via more direct links. We also already have several independent links to the US, so it wouldn't even be much benefit to us as a backup.

According to this random site, Sydney to San Jose is almost 12,000 km (by air). Sydney to Tokyo is 7,700 km. The press release declares that the new cable will be approximately 10,000 km, so that's around an extra 5,000 km via this route minimum. I suspect any run from Australia to Japan isn't going to be particular direct though; AJC is apparently 12,700 km.

This PDF provides some maps of the approximate cable locations. It has one marked "New Japan-US Plans" which might be referring to the Unity cable.