Slashdot Mirror
New Ethernet Standard — Both 40 and 100 Gbps
Artemis recommends a blog entry that does a nice job of summarizing the history and current state of the Higher Speed Study Group and the IEEE's next-generation Ethernet standard. "When IEEE 802.3ba was originally proposed [there] were multiple possible speeds that were being discussed, including 40, 80, 100, and 120Gbps. While there options were eventually narrowed down to just two, 40 and 100Gbps, the HSSG had difficulties [deciding] on the one specific speed they wanted to become the new standard... [T]wo different groups formed, one which wanted faster server-to-switch connections at 40Gbps and one which wanted a more robust network backbone at 100Gbps... Unable to come up with a consensus the HSSG decided to standardize both 40Gbps and 100Gbps speeds..."
You misunderstand; one group said "We need to connect our servers to the switches with a faster connection." The other group said "we need to make our network backbone more robust by adding faster connections between buildings and such." The group that needed faster server-switch speeds don't need 100Gbps, they just need better than what they've got. The group that needed faster building-building/infrastructure links didn't believe 40Gbps is fast enough.
Adding both takes care of both groups of people.
"Victory means exit strategy, and it's important for the President to explain to us what the exit strategy is." G.W.Bush
The big problem with ethernet's design was its "spew everything to everyone" mentality. In practice, this was fixed by good switches becoming almost as cheap as hubs.
The main alternative to ethernet was token ring, which works much like a meeting where you have big stick that's passed around, and only the person with the stick can talk.
Not a typewriter
It's a press release. Check out ITwire.au, or do a google news search for HSSG. You'll see that the release went out 7/23, with almost everyone publishing on 7/24. This guy was just a day late (7/25).
"Trolls they were, but filled with the evil will of their master: a fell race..." -- J.R.R. Tolkien on Olog-hai
If you want all the gory details rather than a copy of a summary of a summary, here is a link to all the presentations at the meeting.
. html
http://www.ieee802.org/3/hssg/public/july07/index
Read through the minutes (warning PDF) to get a summary.
Motion #4: Move that the HSSG adopt the following objectives in replacement of
existing HSSG objectives:
o Support full-duplex operation only
o Preserve the 802.3 / Ethernet frame format utilizing the 802.3 MAC
o Preserve minimum and maximum FrameSize of current 802.3 standard
o Support a BER better than or equal to 10-12 at the MAC/PLS service interface
o Provide appropriate support for OTN
o Support a MAC data rate of 40 Gb/s
o Provide Physical Layer specifications which support 40 Gb/s operation over:
- at least 100m on OM3 MMF
- at least 10m over a copper cable assembly
- at least 1m over a backplane
o Support a MAC data rate of 100 Gb/s
o Provide Physical Layer specifications which support 100 Gb/s operation over:
- at least 40km on SMF
- at least 10km on SMF
- at least 100m on OM3 MMF
- at least 10m over a copper cable assembly
Looks like the 40 allows for fiber or copper connections, while the 100 is pretty much fiber-only (for now?). Fiber is still far more expensive than copper, especially when you're just interconnecting two switches that are next to one another in the rack.
What does the 40Gb standard have that the 100Gb standard doesn't cover?
In one word: cost. The 100Gb connection is limited to fibre optics, whereas the slower connection support copper. Fibre optics are still more expensive than copper. It should also be noted that backbones deal with more traffic than non-backbone networks. Think of the difference between inter-city high ways and local back streets and you should get the picture.
Jumpstart the tartan drive.
The FA says that 40gbps is intended for server-to-switch connections. 100meters should be plenty for that. How often is your server 40 kilometers from the nearest switch?
I'd also suspect that 40gbps will be a whole lot cheaper than 100gbps.
There is already precedent for this at 10G. The LAN people wanted the data rate to be 10.0 Gbps so that it was exactly 10x 1G while the WAN people wanted something compatible with SONET OC-192 wide area transport gear (9.95328 Gbps including framing bits). So they adopted both. They're not compatible at the physical layer so you'd never plug one into another. However they use compatible layer 2 formats so it's easy to switch packets from one to another.
>High Speeds Standards Group. How hard is it to read the summary? Slashdot: where people don't only RTFA, they don't RTFS.
No. It's High Speed Study Group. In IEEE 802 this makes a huge difference.
A study group studies and recommends what standards are to be written by a Working Group (in this case, the WG is 802.3). They do this by arguing for a while then drafting a scope and purpose for the new spec (you'll find this in the first few pages of each IEEE spec). This is sent up the hierachy (the IEEE 802 EC (executive committee) and IEEE SA NESCOM (IEEE Standards Association New Standards Committee)The Working Group then goes off and writes the spec if the EC and NESCOM approve the PAR (Project Authorization Request).
So the HSSG is not a standards writing group at all, it is a bit of pre work to decide what work is going to be done. Arguing over link speeds is exactly the sort of arguing it is chartered to do.
Evil people are out to get you.
When 10Mb Ethernet came out there was widespread debate about its performance, because computers weren't fast enough to saturate it. It was probably the same for 100Mb, and I know the early 1Gb NICs could only handle ~700Mb.
Let me clarify this even more. The 40Gb standard is aimed at LANs. The 100Gb standard is aimed at WANs / the Internet backbone. One is a method well suited to connecting machines in one room or a building to each other, the other is a way to connect cities. This is actually a very remarkable new role for "ethernet" standards, since most backbone trunk lines use special protocols today.
Make sense?
I like this definition:
Narrowband, Wideband, and BroadbandNarrowband is a transmission medium or channel with a single voice channel (with a carrier wave of a certain modulated frequency). Wideband is a transmission medium or channel that has a wider bandwidth than one voice channel (also with a carrier wave of a certain modulated frequency). Broadband refers to telecommunication that provides multiple channels of data over a single communications medium using frequency division multiplexing.
Through the Wires: Bandwidth
Mea navis aericumbens anguillis abundat