/. Terabit Ethernet is Dead, for Now

Dan Shechter danshtr at gmail.com
Thu Sep 27 13:26:34 UTC 2012

If they would have rolled out 1000G networks now, I guess we will have to
plug in 17 MTP interfaces ;)

Dan #13685 (RS/Sec/SP)
 The CCIE troubleshooting blog: http://dans-net.com
 Bring order to your Private VLAN network: http://marathon-networks.com

On Thu, Sep 27, 2012 at 2:51 PM, Eugen Leitl <eugen at leitl.org> wrote:

> http://slashdot.org/topic/datacenter/terabit-ethernet-is-dead-for-now/
> Terabit Ethernet is Dead, for Now
> by Mark Hachman | September 26, 2012
> A straw poll of the IEEE's high-speed Ethernet group finds that 400-Gbits/s
> is almost unanimously preferred.
> Sorry, everybody: terabit Ethernet looks like it will have to wait a while
> longer.
> The IEEE 802.3 Industry Connections Higher Speed Ethernet Consensus group
> met
> this week in Geneva, Switzerland, with attendees concluding—almost to a
> man—that 400 Gbits/s should be the next step in the evolution of Ethernet.
> A
> straw poll at its conclusion found that 61 of the 62 attendees that voted
> supported 400 Gbits/s as the basis for the near term “call for interest,”
> or
> CFI.
> The bandwidth call to arms was sounded by a July report by the IEEE, which
> concluded that, if current trends continue, networks will need to support
> capacity requirements of 1 terabit per second in 2015 and 10 terabits per
> second by 2020. In 2015 there will be nearly 15 billion fixed and
> mobile-networked devices and machine-to-machine connections.
> The report goes on to predict that, from 2010 to 2015, global IP traffic
> will
> experience a fourfold increase from 20 exabytes per month in 2010 to 81
> exabytes per month in 2015, a 32 percent CAGR. Storage growth is expected
> to
> grow to 7910 exabytes in 2015, with over half of it accessed via Ethernet.
> Of
> course, one of the first places the new, faster Ethernet links will occur
> will be in the data center.
> With that in mind, the IEEE 802.3 group began formulating a response.
> However, virtually all attendees seemed to be in agreement before the
> meeting
> opened, as only one presentation focused on the feasibility of one-terabit
> Ethernet, eventually concluding that 400 Gbits/s made more sense in the
> near
> term.
> Kai Cui and Peter Stassar from Huawei Technologies suggested that the most
> cost-effective method for developing a 1-terabit Physical Medium Dependent
> (PMD) would be to leverage today’s 100-Gbit technology, which isn’t yet in
> high volume, and therefore not cost-optimized. “[The] cost target for 1Tb/s
> needs to be at or below 100G cost/bit*sec and required R&D investments
> should
> be modest,” they wrote as part of their presentation.
> “100GbE technology based architecture would imply 40 lanes at 25G, which
> clearly would imply impractically big packages and large amount of
> interface
> signals,” Cui and Stassar added, which would need to reduce the number of
> electrical and optical interface lanes to enable a reasonable package size.
> While alternative modulation formats could be used (5λx200G DP-16QAM, 4
> bits/symbol, 25G) “neither the multi-level nor the phase modulation format
> based technologies have been demonstrated to be sufficiently mature to
> justify usage in client PMDs towards 100Gb/s to 1Tb/s applications.”
> They concluded: “1Tb/s does seem a ‘bridge too far’ at least for the
> coming 3
> to 4 years.”
> Chris Cole of optical components maker Finisar presented the case for a
> 400-Gbit CFI, with backing from Brocade, Cisco, HP, IBM, Intel, Juniper,
> and
> Verizon, among others.
> Like Huawei’s Cui and Stassar, Cole indicated that 400-Gbit Ethernet can
> reuse 100 GbE building blocks, and fits within the existing dense 100 GbE
> roadmap. Faster data rates require “exotic” implementations, with higher
> R&D
> investments required and a longer time to market. “Data rates beyond
> 400Gb/s
> require an increasingly impractical number of lanes if 100GbE technology is
> reused,” he said.
> 400 Gbit/s also makes more sense than a 4×100 Gb/s link aggregation, Cole
> added, as fewer items promotes management efficiency. Individual link
> congestion is also a concern: “Without faster links, [the] link count grows
> exponentially, therefore management pain grows exponentially.”
> Cole suggested that a potential 400 Gb/s MAC/PCS ASIC could be fabricated
> in
> either 20- or 28-nm CMOS, using a 400-bit wide bus and a 1 GHz clock rate.
> “There is a strong desire to reuse 802.3ba, 802.3bj, and 802.3bm technology
> building blocks,” he said.
> That’s not to say that terabit Ethernet won’t be needed, Cole concluded, or
> 1.6 terabit Ethernet, at that. The timeframes for those followon CFIs could
> be between 3 to 6 years, he said.
> The CFI hasn’t formally occurred; until it does, nothing has been decided.
> So
> far, the most likely dates for formalizing the CFI will take place in
> either
> November or next month. But at this point, it looks like terabit Ethernet
> is
> a dead duck, at least for the near future.

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