* Posts by Peter Rathlev

17 posts • joined 25 Jul 2011

The internet IS a series of tubes. Kinda: A Reg 101 guide to cabling

Peter Rathlev

Re: Errrr

It started out with this:

> Unlike the other Ethernet standards, 10GbE provides the only

> full-duplex, point-to-point links usable for connecting

> network switches.

There have been "full-duplex point-to-point links usable for connecting network switches" since the very first actual full-duplex switches. The first I remember was 100 Mbps, but I'm pretty sure people were doing full duplex links between switches before that.

When using pluggables (e.g. SFP) the type of cabling you can use depends on the type of pluggable, not the switch. The pluggable acts as a modularization boundary. There are of course things that would need a converter (using SC connectors with a SFP-only switch) but that's got nothing to do with the switch. The only other common plug is the 8P8C, and here you have to choose between Cat6, Cat6a and Cat7. Or whatever comes next. But still the switch doesn't care.

10GBASE-T also runs on plain Cat6, though only up to 55m. The article makes it sound like you need Cat6a or better.

MMF is more expensive than SMF, not the other way around as the article states. SM transceivers are more expensive to produce though, but they have steadily been getting cheaper over the years.

10GBASE-SR doesn't have "the smallest form-factor". It's not a physical specification. SFP+ is though, and most of the 10GBASE standards are implemented by SFP+ transceivers. (Not 10GBASE-T because of power requirements and similarly not some of the more exotic long range optics.)

In the table it says CX4 supports up to 20G. It doesn't for Ethernet, where it's only 4 x 3.125 Gbps signaling and an actual capacity of 10 Gbps. But then the table of course lists a lot of things that aren't Ethernet at all.

Recommending using MMF for new installs is probably somewhat a matter of taste, but since SM transceiver costs are way down and since SMF is much more future proof I would certainly recommend using that for new 10G installs over anything MMF.

While the article mentions 10GBASE-T many times is does not list the important disadvantage of power consumption. It has improved over the years but is still around 5-6W per port, compared to about 1W per port for SM LH/LX ("10km") transceivers.

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Peter Rathlev

Re: Errrr

This article firmly places itself outside both categories; it's too little tongue-in-cheek to be a spoof and the subject is quite simple for most readers here. Many claims in the article are patently absurd, it's not just you (or anyone else) being dumb. And the article could use a little copy-editing too.

Most of the paragraphs contain errors or misleading information. I don't really want to spend the energy pointing them out unless someone really wants it. (And it's a little too much for just a "Send corrections" email...)

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iOS 7's weak random number generator stuns kernel security – claim

Peter Rathlev

XKCD was first

http://xkcd.com/221/

http://www.engadget.com/2010/12/29/hackers-obtain-ps3-private-cryptography-key-due-to-epic-programm/

Judging from both the "Last-Modified:" header of the XKCD image and the Wayback Machine it seems Engadget borrowed it from Randall, not the other way around. Which may have been your point, but I just wanted to make sure we're all on the same page. :-)

XKCD uses a CC BY-NC license so Engadget should have mentioned from where they borrowed the image.

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Multipath TCP: Siri's new toy isn't a game-changer

Peter Rathlev
Facepalm

Hmm...

Apart from spelling Geoff's surname wrong there are a few misunderstandings in the article.

RFC 6824 takes NAT into account and has a whole chapter (6) dedicated to middlebox interactions. Of course a sufficiently stupid middlebox can break anything, but MPTCP will then just fall back to regular TCP with a small delay. Keep in mind that each subflow is (almost) a regular TCP session for everyone but the two end hosts. One can probably assume that they tested this on at least the most common middleboxes out there.

The primary use case for Apple is probably resilience and not more bandwidth, i.e. being able to switch seamlessly between two otherwise unrelated connections and only being minimally affected when one disappears.

The chicken-and-egg part isn't much of a problem. We're talking OS level stuff so the application developer doesn't have to decide. And since everything is backwards compatible you can implement it little by little. Compare it to TLS for SMTP.

Regarding VPNs and security, MPTCP also takes this into account. A new subflow cannot send data before the other end has been verified as the original partner. Trying to create the subflows will leak information about the other end's address(es) but VPN software could prohibit this like any other NAC feature.

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Firefox OS mobilises HTML5, without the added Steve Jobs

Peter Rathlev
Go

Re: I don't see this as an advantage @Tim 14:28

Limited and unsophisticated language? A good programmer can write FORTRAN in any language.

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Oracle fudges touts Sparc SuperCluster prowess

Peter Rathlev

Re: SPARC, not Sparc ! (@AC 14:03)

Well it so happens that I'm seriously retarded, so much that I just simply don't know where to look that up. Can you please provide some pointer? I hear you saying that using a name that is not a trademark ("Sparc" or "sparc") when referring to something trademarked ("SPARC") is a trademark violation? So calling the Sparc a "CPU" is wrong too? (Yeah, the lack of capitalization is entirely not on purpose, I just stopped thinking.)

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Peter Rathlev
Meh

Re: SPARC, not Sparc !

Well, IANAL but I fail to see how El Reg's use can be considered trademark violations. They're clearly referring to the party that holds the SPARC‰® trademark. I would've thought observing trademarks just means that you cannot use the mark to refer to something else. I didn't think trademark law forced everybody to always spell everything correctly.

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Giant super-laser passes 500 TRILLION watts

Peter Rathlev
Boffin

As noted by the lab, 500 Terawatts is more than 1,000 times as much power as is consumed in the United States at any instant

Except at the moment they fired it, right? It's placed inside US borders.

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LOHAN's fantastical flying truss menaces kiddies

Peter Rathlev
Holmes

Re: Death from the skies

Yeah. Isn't the typical bullet less than 10g? They're not made from balsa wood of course. :-)

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Shuttleworth remixes Ubuntu... for biz users

Peter Rathlev
Linux

Things working on GNU/Linux

"Only the other day someone said 3G dongles didn't work - they do". Yeah, I hear that a lot too. I almost started believing it, since never using Windows means I don't know what people place as a baseline for "easy".

On what I use (Fedora 14, CentOS 6.2 Desktop) you just plug in the device and tell NetworkManager what country + provider you're using, and then it works. Tried with three different dongles, all were this easy. As is conneting via Bluetooth to my phone and using its 3G connection.

It was actually hard-ish when I was still insisting on using things like wvdial and other shell based things. But it certainly hasn't been hard the past few years.

And then I found how how "easy" it _really_ was on a Windows. Wow. Just wow. Even colleagues of mine working with Windows can't make it work right. Weren't "drivers" a last century thing?

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Pope's PR says Vatican in grip of WikiLeaks-style scandal

Peter Rathlev

Yeah, Father Gabriele is right. The devil's been walking those corridors for the last millennium and a half, m-kay.

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Duff Mars probe team sweats under Medvedev menaces

Peter Rathlev
Joke

What failures...?

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'Puzzling structures on surface' of YU55 spaceball

Peter Rathlev
Alien

@ShelLuser 16:31

According to Wikipedia the escape velocity from LEO is ~10.9 Km/s, so wouldn't must of the manned moon missions* have acheived velocities at least in that range?

*) I know they were faked of course.

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Router glitch causes widespread net outages

Peter Rathlev
Joke

Candlejack?

You didn't even say Candlejack... That's supposed to

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Peter Rathlev
Facepalm

@AC 20:54

Yeah, don't buy Juniper. And make sure that every network that you would traverse to reach any place you want also would not buy Juniper. And then hope that this only ever happens to Juniper. :-)

E.g. http://www.cisco.com/warp/public/707/cisco-sa-20100827-bgp.shtml

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Amateur claims crack of final Zodiac Killer cipher

Peter Rathlev
Facepalm

@Loyal Commenter

Not only that, he apparently couldn't even get this attempt at a Vigenere-ish solution right, even though it's hard not to get right as you point out. According to doranchak's comment in the top of the stack (or bottom, depending of preference) the shifts mentioned on his notes would not yield the result he proposes.

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Peter Rathlev
Happy

It's fun reading the comments!

I agree with sabba; if El Reg had themselves pointed us to all the people proving Starlicker blatantly wrong it would only be half as funny. That would still rather funny of course.

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