Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Bob Metcalfe wins Turing Award

amturing.acm.org

Post reply on HN
Print view View original

141–150 of 238 posts

Re: Bob Metcalfe wins Turing Award

#141

Post by ArtRichards »

I think around 2011, they offered the first UT Longhorns Startup course, it was cool and hip and new, and they'd flown in mentors from SV and other places, so I figured, why not?

So, after applying, I had shown up at a hotel near campus. While waiting in the lobby, playing with their unsecured wifi, a rather distinguished looking gentleman came up to me, and asked, Hey are you here for the Startup Course interviews?

Yeah...

Well, why are you here in the lobby?

Well, I was told to wait here, and its been a half hour nobody called me.

He gave me a look, direct in the eyes, and said, oh, really? And you're just going to sit here and wait?

I was dumbfounded. Of course, it made sense, but it felt.. I didn't want to piss off the organizers, right?'

"Go in there, and get it!" as he clawed the air like a tiger. Damn, he was right.

So i ambled in, looked around, found a seat near the guy organizing (Josh Baer, another awesome guy) introduced myself and sat at a table by myself, just waiting for an in...

Then the gentleman from the lobby came in and sat in front of me, with a big grin.

Hi?

Hi.

You're a part of this?

Yes, my name's Bob Metcalfe.

Cool, thanks for the pep talk. So, whats your story?

Well, I founded 3Com, and helped come up with Ethernet.

Oh... damn.. cool..

...And my life has never been the same since!

If you read this, thanks Bob.

Re: Bob Metcalfe wins Turing Award

#142

Post by zamadatix »

throw0101b wrote: post #107

Somewhat related: The choice of 48 bits for the hardware/station address seems to have been a pretty good choice: it's been 40+ years and we still have no run out. I'm curious to know if anyone has done the math on when Ethernet address exhaustion will occur. While the Ethernet frame has been tweaked with over the decades, addressing has been steady. Curious to know if any transition will ever been needed and how wou…

Some quick napkin math on the current MAC vendors database: 46 bits of a MAC address are reserved for universally administered unicast (i.e. a globally unique MAC assigned to identify a device). So far we have assigned ~570 billion addresses via 24/28/36 bit range assignments for the same purpose which represents a little under 1% of the space. So nothing urgent, though if we stuck with Ethernet as much as we use it today then in At the same time there are also 46 bits of locally administered unicast addresses and, unlike IP, Ethernet addresses only care about the local network (and this isn't a "because we've co-opted them to to save space just like NAT broke IP protocols" rather the design intent of Ethernet). Even if you had 10 billion LANs with 100 devices each and they all used this random non-unique assignment there would only be a ~50% chance there one or more devices would have a collision.

The only real advantage I've ever been able to find of programming in unique MAC addresses vs random MAC addresses you can look up what company the MAC was assigned to. It may seem like there is a risk random assignment can be done poorly (e.g. not very randomly) but honestly the same risk exist with assigned ranges as seen by network vendors cheaping out and re-using their MAC blocks (which is significantly more likely to conflict than if they just used random locally administered addresses in the first place).

Re: Bob Metcalfe wins Turing Award

#143

Post by zamadatix »

lispython wrote: post #17

A veritable hero of our times boasts a mere 688 followers on his Twitter account: https://twitter.com/RobertMMetcalfe (as of the dispatch of this message).

It's more a personal account that's 1 year old which opens with a tweet on cancel culture followed by his political leanings, cryptocurrency posts, and an overwhelming amount of basketball stats. It does have the occasional post about his involvement in geothermal energy though but beyond that following the account isn't going to get you any content he's known and respected for.

Re: Bob Metcalfe wins Turing Award

#145

Post by jandrese »

AlbertCory wrote: post #138
retrocryptid wrote: post #136

Earlier quoted context omitted.

One more book on the stack... Now I have to read it to find out how ARCNet worms it's way into a novel about sili valley.

This part's not in the book: Gordon Peterson, the architect of ARCNet, was a major source for me. He talked to Bob back in the day. Gordon's still bitter about it, and will gladly tell you why Ethernet is inferior.

Ethernet is one of those case studies in "worse is better".

I remember the old saying that "Ethernet doesn't work in theory, but it does in practice". Mostly referring to the CSMA/CD scheme used before switches took over.

The competitive advantage of being built out of cheap commodity hardware and cabling is hard to overstate. Nobody likes dealing with vendors, their salespeople, and especially support contracts. Especially since that is always more expensive and often solves problems you don't have, like minimum latency guarantees, at the cost of throughput and complexity.

Re: Bob Metcalfe wins Turing Award

#146

Post by toast0 »

throw0101b wrote: post #111
RF_Savage wrote: post #88

Earlier quoted context omitted.

2.5Gb is downshifted 10Gb with the same line coding, just with 1/4 the symbol rate. This means that it inherits all the complexities of 10GbE, while tolerating cheaper connectors and cables. 10GbE uses DSQ128 PAM-16 at 800Msym/s. 2.5G just does quarter-rate at 200Msym/s. 1000BaseT uses trellis coded PAM-5, a significantly less complex modulation. When one factors in the complexity of the line code and all equalisatio…

> tolerating cheaper connectors and cables I always find the graphic below handy for telling which Cat cable can handle which Gig speed: * https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair#Var...

It's not really about can handle, but more is specified to handle at maximum length in a dense conduit.

At shorter lengths, and in single runs, it's always worth trying something beyond what the wiring jacket says. I've run gigE over a run with a small section of cat3 coupled to a longer cat5e run (repurposed 4-pair phone wire), and just recently setup a 10G segment on a medium length of cat5e. The only thing is while I think 2.5G/5G devices do test for wiring quality, the decimal speeds don't, auto-negotiation happens on the 1Mbps link pulses, unmanaged devices can easily negotiate to speeds that won't work, if your wiring is less than spec, you need to be able to influence negotiation on at least one side, in case it doesn't work out.

Re: Bob Metcalfe wins Turing Award

#147

Post by jandrese »

Dalewyn wrote: post #39
themoonisachees wrote: post #20

Earlier quoted context omitted.

2.5G or even 10G is not that much more expensive and companies making consumer electronics sell it as a considerable premium for what is essentially the same cost difference as making a 8gb vs 16 gb flash drive. Of course, regular internet users don't need more than 2.5G (and couldn't use it in most of the world due to ISP monopolies) so anything faster than gigabit is a target for segmentation.

Rant aside, I think there is an argument to be made that 2.5gbps switches "should" be cheaper now that 2.5gbps NICs have become fairly commonplace in the mainstream market. Case in point, I have a few recent-purchase machines with 2.5gbps networking but no 2.5gbps switch to connect them to because I personally can't justify their cost yet. I suppose I could bond two 1gbps ports together, or something, but I like to t…

The problem with 2.5G is that it's not enough of an upgrade over 1G to warrant buying all new switches and NICs to get it. For that matter few home users push around enough data for 10G to be a big win.

IMHO this is why Ethernet has stalled out at 1G. People still don't have large enough data needs to make it worthwhile. See also: the average storage capacity of new personal computers. It has been stuck around 1TB for ages. Hell, it went down for several years during the SSD transition.

Re: Bob Metcalfe wins Turing Award

#148

Post by toast0 »

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…

You don't need an interrupt per packet, at least not with sensible NICs and OSes. Something like 10k interrupts per second is good enough, pick up a bunch of packets on each interrupt; you do lose out slightly on latency, but gain a lot of throughput. Look up 'interrupt moderation', it's not new, and most cards should support it.

Professionlly, I ran dual xeon 2690v1 or v2 to 9Gbps for https download on FreeBSD; http hit 10G (only had one 10G to the internet on those machines), but crypto took too much CPU. Dual Xeon 2690v4 ran to 20Gbps, no problem (2x 14 core broadwell, much better AES acceleration, faster ram, more cores, etc, had dual 10G to the internet).

Personally, I've just setup 10G between my two home servers, and can only manage about 5-8Gbps with iperf3, but that's with a pentium g2020 on one end (dual core Ivy Bridge, 10 years old at this point), and the network cards are configured for bridging, which means no tcp offloading.

Edit: also, check out what Netflix has been doing with 800Gbps, although sendfile and TLS in the kernel cuts out a lot of userspace, kind of equal but opposite of cutting out kernelspace, http://nabstreamingsummit.com/wp-content/uploads/2022/05/202...

Re: Bob Metcalfe wins Turing Award

#149

Post by jandrese »

throw0101b wrote: post #112
dale_glass wrote: post #96

Earlier quoted context omitted.

You can have 10G with eg, Mikrotik at a reasonable price. One problem with it is that the copper tech is just power hungry. It may actually make sense to go with fiber, especially if you might want even more later (100G actually can be had at non-insane prices!) Another problem is that it's CPU intensive. It's actually not that hard to run into situations where quite modern hardware can't actually handle the load of…

> 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...

The other issue is that unless your computer is acting as a router or a bridge, you need to do something with that 10GB data stream. SSDs have only recently gotten fast enough to just barely support reading or writing that fast. But even if you do find one that supports writes that fast a 10GbeE card could fill an expensive 4TB drive in less than an hour. Good luck decoding JPEGs and blitting them out to a web browser window that fast.

Re: Bob Metcalfe wins Turing Award

#150

Post by jandrese »

bombcar wrote: post #101
zokier wrote: post #33

Earlier quoted context omitted.

It is also lesson of doing something now and rewriting it later. For example no modern ethernet network uses cd/csma anymore and it was pretty iconic part of original ethernet. Overall ethernet on physical layer has seen quite an evolution from coax and vampire taps, to twisted pair and hubs, to switched networks, and nowdays wireless, single-pair, optical, and virtual networks

I remember when hubs were still common; I don't know if any have been made for decades. Even bargain basement switches are switched now, and often even have spanning tree and other 'previously enterprise' features.

Hubs max out at 100Mbps. Everybody today is using Gigabit, so they're effectively extinct.

Even at 100Mbps hubs were on the way out. They were pretty hacky. The hardware had two different hubs internally and joined them together with a bit of logic, but that logic was somewhat failure prone and it was common to have 10/100 hubs where the 10 clients couldn't talk with the 100 clients and vice versa. Autodetection was at best a roll of the dice so most people wired down their port settings instead. Everybody hated them and switches got cheap real fast so they didn't last very long. The only thing they were good for was network diagnostics.

Post reply on HN