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Bob Metcalfe wins Turing Award

amturing.acm.org

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Re: Bob Metcalfe wins Turing Award

#221

Post by riceart »

jacquesm wrote: post #207
riceart wrote: post #193

Earlier quoted context omitted.

A little confirmation bias on this one. In addition to the infamous internet will collapse prediction he was also pretty whole hog on the Segway scooter revolutionizing transit.

So let me enlighten you a bit: we did collapse the internet, and got a testy email from a bunch of backbone maintainers that they were going to block our live video streams (on port 2047) in four weeks time or so. Which resulted in us moving to the other side of the Atlantic to relieve the transatlantic cable. So even if it didn't make the news Metcalfe was 100% on the money on that particular prediction. The Segway…

He made a very specific prediction - it didn’t pan out - that there have been near misses and even global degradation events multiple times in the past 3 decades is not relevant. He admitted he was wrong and literally ate his words.

Re: Bob Metcalfe wins Turing Award

#222

Post by [deleted] »

fsckboy wrote: post #199
passwordoops wrote: post #40

Earlier quoted context omitted.

HN comment of the year winner right here! Makes you wonder how many other laws are built on nothing. If there's one thing I leaned doing a Ph.D. is if you dig deep enough, you find many foundational laws of nature rely on some necessary assumption that, if proven incorrect, would topple the whole thing

> Makes you wonder how many other laws are built on nothing. variance/standard deviation (also btw, a sum of squares concept) it marks the inflection points on the gaussian curves, but so what, the 2nd derivative points to something significant about the integral? not really. But even if we accept that it does, what does two standard deviations mean? a linear double on the x coordinates says what about the a hairy po…

[deleted]

Re: Bob Metcalfe wins Turing Award

#223

Post by iptrans »

toast0 wrote: post #178
iptrans wrote: post #165

Earlier quoted context omitted.

Interrupt moderation only gives a modest improvement, as can be seen from the benchmarking done by Intel. Intel would also not have gone through the effort to develop DPDK if all you had to do to achieve linerate performance would be to enable interrupt moderation. Furthermore, quoting Gbps numbers is beside the point when the limiting factor is packets per second. It is trivial to improve Gbps numbers simply by usin…

I'm quoting bulk transfer, with 1500 MTU. I could run jumbo packets for my internal network test and probably get better numbers, but jumbo packets are hard. When I was quoting https download on public internet, that pretty much means MTU 1500 as well, but was definitely the case. If you're sending smaller packets, sure, that's harder. I guess that's a big deal if you're a DNS server, or voip (audio only); but if you…

Bulk transfers aren’t that being interesting from a networking perspective.

You gonna have a bad time if you optimize only for the best case scenario.

Even using IMIX is a low bar. The proper way to do things is linerate using small packets.

Re: Bob Metcalfe wins Turing Award

#224

Post by williamDafoe »

irq-1 wrote: post #200
williamDafoe wrote: post #126

Earlier quoted context omitted.

Original DIX Ethernet was standardized by my manager, David Redell of Xerox. It was the bare minimum to do the job, 6-byte station destination, 6-byte source address, 2-byte packet length, a 2-byte Ethertype field (the latter 2 were combined for networks with hardware framing), and 32-bit CRC. NO arc in the hardware. It leveraged the move to byte-based memories and small CPUs. It followed the end-to-end principle in…

Maybe you know, why isn't the CRC at the end? Then you could stream the packet instead of needing to construct it and then go back to the header to write the CRC.

The CRC is at the end, sorry if my explanation did not make it clear. It comes after all of the payload bytes.

https://en.wikipedia.org/wiki/Ethernet_frame

Re: Bob Metcalfe wins Turing Award

#225

Post by williamDafoe »

williamDafoe wrote: post #126
hoseja wrote: post #7

What's the killer feature that differentiates Ethernet from other phy protocols?

Original DIX Ethernet was standardized by my manager, David Redell of Xerox. It was the bare minimum to do the job, 6-byte station destination, 6-byte source address, 2-byte packet length, a 2-byte Ethertype field (the latter 2 were combined for networks with hardware framing), and 32-bit CRC. NO arc in the hardware. It leveraged the move to byte-based memories and small CPUs. It followed the end-to-end principle in…

In the original ethernet design, routers were not used (because 8-bit processors were too slow and 16-bit processors were just starting to emerge). So the original standard proposed repeaters as the way to extend a large network, and this was a very very cheap analog way to grow your network. It was quite common to have a whole building or even several nearby buildings on one ethernet and then a high speed (i.e. 56 Kbps or maybe even a T-1) link to other buildings either nearby or in other cities.

Re: Bob Metcalfe wins Turing Award

#226

Post by Dalewyn »

amoss wrote: post #219
Dalewyn wrote: post #155

Earlier quoted context omitted.

2.5gbps is literally 2.5x times the speed of gigabit ethernet, so that's going to be very noticable even for most home users if they do any amount of LAN file sharing. It's really just the cost that's the problem, because paying 4x to 5x or even 6x times the cost of gigabit hardware for a 2.5x times performance boost doesn't make a lot of sense. If 2.5gbps peripheral hardware costs would come down I will happily bet…

This assumes that the LAN is the bottleneck. Gigabit ethernet tops out at 120MB/s, which is about the speed of spinning rust on a NAS.

Yeah, but you probably have more than one drive RAID'd in that NAS so you will almost certainly get faster transfers (granted: sequential) if ethernet wasn't the bottleneck.

2.5gbps ethernet translates to roughly 250MB/s in real world transfer speeds, that's a lot. Literally over double real world gigabit transfer speeds, and far less likely to bottleneck you.

Re: Bob Metcalfe wins Turing Award

#227

Post by jabl »

iptrans wrote: post #120
throw0101b wrote: post #112

Earlier quoted context omitted.

> Another problem is that it's CPU intensive. Are there 10GigE cards that do not do things like IP/TCP offloading at this point? Offloading dates back to (at least) 2005: * https://www.chelsio.com/independent-research-shows-10g-ether... * https://www.networkworld.com/article/2312690/tcp-offload-lif...

TCP/IP offload isn’t the issue. The core problem is that the Linux kernel uses interrupts for handling packets. This limits Linux networking performance in terms of packets per second. The limit is about a million packets per second per core. For reference 10GE is about 16 million packets per second at line rate using small packets. This is why you have to use kernel bypass software in user space to get linerate perf…

Most Linux network drives support NAPI since a couple of decades. No panacea of course, but still, far from having one interrupt per packet.

Re: Bob Metcalfe wins Turing Award

#228

Post by OJFord »

mixmastamyk wrote: post #191
lr4444lr wrote: post #56

Earlier quoted context omitted.

I respect Metcalfe a lot, but halfway through undergraduate discrete math it was pretty obvious to most people in the class even before seeing a formal proof that a fully connected graph has O(n^2) edges. I just figured that people wowed by "Metcalfe's Law" were business types who didn't any formal theory into computing.

I thought it was a "combinatorial explosion?" https://en.wikipedia.org/wiki/Combinatorial_explosion#Commun...

(n²-n)/2 is O(n²) as GP claimed (not that it's exactly n², unless edited before I saw it), you're both right.

Re: Bob Metcalfe wins Turing Award

#229

Post by 1970-01-01 »

Around 2002 he had the wild idea about Ethernet for intra-bus and peripheral communication. Nobody in the room thought it was a good idea. Glad he was smart enough to abandon that idea and stick with networking. I didn't want my mouse and keyboard getting an IP address.
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