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Is it just me or is networking really hard?

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Re: Is it just me or is networking really hard?

#161

Post by nacs »

samplonius wrote: post #134
nubb wrote: post #122

Earlier quoted context omitted.

UDP is used when it's designed by network engineers. That's why we have VOIP and video streaming - all are served UDP. dont get me started on the lack of multicast out there. imagine game servers running multicast. one day.

Most video streaming today is not served by UDP, but by TCP. Only live video uses UDP. Stored video (ex. Netflix) is all sent via TCP.

> Only live video uses UDP

Not necessarily. One of the largest live video streaming services, Twitch.tv, uses TCP for streaming.

Re: Is it just me or is networking really hard?

#162

Post by __d »

OliverJones wrote: post #39

I sometimes ask the question "how does the internet work?" in interviews. The vague and wrong answers I hear are astonishing. I'm looking for a basic understanding of the layering of TCP, or RDP, or ICMP (or anything actually) on top of IP. I don't get that level of insight much. The people who do have that insight usually can go deeper -- slow-start, BGP, etc. I wonder if we have a modern version of C.P. Snow's mid-…

I used to ask job applicants for a network-oriented programming position to explain how IP packets were delivered between machines: first on a LAN, and then on a WAN.

The vast majority had no idea what went on beneath the BSD sockets API.

Similarly, asking developers roughly how computation occurs (memory, cache, registers, instruction sets, etc) typically drew answers well into the comical spectrum.

Yes, I think our education of engineers is failing them miserably.

Re: Is it just me or is networking really hard?

#163

Post by chetanahuja »

efaref wrote: post #135
chetanahuja wrote: post #123

Earlier quoted context omitted.

Well... those are examples of designing custom protocols on top of UDP. These network engineers, who I assume are specially trained in some secret govt. facility for network commando training, actually have to understand the problem at hand and design something specifically for the problem. Calling these protocols just "UDP" is like saying something like "I use wheels to commute from home to office everyday"

I would hardly call protocols like [SIP]( https://www.ietf.org/rfc/rfc3261.txt ) and [RTP]( https://www.ietf.org/rfc/rfc3550.txt ) "custom". There are many more standard protocols out there than just TCP and UDP. There's even a "better TCP" in the form of [SCTP]( https://tools.ietf.org/rfc/rfc4960.txt ). The fact is that TCP was the MVP for reliable streams of data on the 1970s internet, and is woefully inadequate fo…

'I would hardly call protocols like [SIP]... and [RTP]... "custom".'

The meaning of "custom" in this context was to distinguish it from a full TCP or raw UDP. Not to imply that there's no standard definitions for VOIP protocols. Quite the contrary in fact. The point being made is that UDP is just a substrate to create other protocols that also need to be designed for a purpose. And just calling all these protocols "UDP" is a mistake.

Btw, not to be argue from authority, but to back my words with some context, I'm responsible for at least one such "custom" protocol myself. https://packetzoom.com/blog/

Re: Is it just me or is networking really hard?

#164

Post by Rapzid »

davnicwil wrote: post #124
akerl_ wrote: post #55

Earlier quoted context omitted.

I'd argue that the cases where a hash table's performance characteristics come into play are few and far between for most developers, and when they do, it's way more relevant that the person have a general idea how to profile perf in their code and say "yup, this is the spot that I need to worry about optimizing first". By marking down people who don't know how to implement a hash table, you're cutting out a large ch…

I did an interview once where they asked me questions around the implementation of a hashmap. At the time I'd been working about a year out of university, and had not in that job come across any situation where I'd needed to know anything about how hashmaps worked under the hood (if anyone had a first job where you did, I'm happy for you, yours was a lot more interesting than mine). Any remnant of an explanation I'd…

Could even flip it around: prepare a simple implementation of a hash map, maybe even in sudo code, and then show it to the interviewee and ask them what's going on/discuss it.

Re: Is it just me or is networking really hard?

#165

Post by jwatte »

nubb wrote: post #122
chetanahuja wrote: post #117

"You can’t even imagine a way that reliability could be implemented on top of UDP that beats TCP? What total bullshit" This. This "TCP already does it best in every situation" is a common trope usually spouted by people who know nothing about what TCP does and why. The easiest way to get over this misconception is to ask yourself, can you think of a protocol that not only works well over all sorts of networks, all th…

UDP is used when it's designed by network engineers. That's why we have VOIP and video streaming - all are served UDP. dont get me started on the lack of multicast out there. imagine game servers running multicast. one day.

Multicast at global scales is fundamentally broken. Every router on the internet would have to know about every potential peer wanting to join a multicast group.

Re: Is it just me or is networking really hard?

#166

Post by jwatte »

nubb wrote: post #122
chetanahuja wrote: post #117

"You can’t even imagine a way that reliability could be implemented on top of UDP that beats TCP? What total bullshit" This. This "TCP already does it best in every situation" is a common trope usually spouted by people who know nothing about what TCP does and why. The easiest way to get over this misconception is to ask yourself, can you think of a protocol that not only works well over all sorts of networks, all th…

UDP is used when it's designed by network engineers. That's why we have VOIP and video streaming - all are served UDP. dont get me started on the lack of multicast out there. imagine game servers running multicast. one day.

Multicast at global scales is fundamentally broken. Every router on the internet would have to know about every potential peer wanting to join a multicast group.

Re: Is it just me or is networking really hard?

#167

Post by pyre »

Dylan16807 wrote: post #146
pyre wrote: post #111

Earlier quoted context omitted.

> You're not going to outperform TCP to do what it's good at. I took this to be something more akin to "never implement your own crypto." If everyone followed that advice there would be no crypto, so it's obviously not blanket advice.

Even looking at it like that, it's wrong. TCP has a lot of tunable parameters where the choices are baked into it, and it assumes that extra round trips are no big deal. Crypto does not have all that many tradeoffs. You just need expert implementation. It's dangerous and unnecessary to do it yourself. For something that is low-bandwidth and latency-sensitive, you can take TCP and make minor adjustments and come out w…

I was using "never implement your own crypto" as an example. I think that "never implement your own crypto" is a more important rule to follow than anything regarding TCP. On the other hand, if you don't know much about networking, trying to reimplement TCP over UDP isn't likely to gain you better performance. As with most things, there is no substitute for knowing what are doing.

Re: Is it just me or is networking really hard?

#168

Post by bjterry »

perlgeek wrote: post #137
OliverJones wrote: post #39

I sometimes ask the question "how does the internet work?" in interviews. The vague and wrong answers I hear are astonishing. I'm looking for a basic understanding of the layering of TCP, or RDP, or ICMP (or anything actually) on top of IP. I don't get that level of insight much. The people who do have that insight usually can go deeper -- slow-start, BGP, etc. I wonder if we have a modern version of C.P. Snow's mid-…

> Are we miseducating our so-called "full-stack" engineers by not offering them a basic understanding of telecom? Or are they not listening? What's that "stack" anyway? Usually I get the impression that people frontend (user-interface, so usually HTML, JS, maybe a thin web app) and backend (API service, business logic and storage in a database). Is understanding of the OS, of the memory model, of networking protocols…

Every time I've heard the term full stack used, it referred to web developers, and I think it just implies that someone could go from nothing to having a full website without outside help. That is, they can create HTML and JavaScript front-end and a back-end using a web framework and a database. Anything outside of that is pretty much ignoring common usage. Obviously it isn't a situation like "if you wish to create a website from scratch, you must first create the universe" because that would be a singularly unhelpful definition of full stack.

Re: Is it just me or is networking really hard?

#169

Post by ibejoeb »

brudgers wrote: post #87
exDM69 wrote: post #23

Earlier quoted context omitted.

To be fair, Gaffer's original articles are well written, thoughtful and informative too. This is him ranting about the unfounded, negative and incorrect feedback he's been receiving about them from people who are willfully ignorant about networking. He could or should have replied with less attitude and more facts, though. I understood what and why he's saying what he is, but I didn't enjoy the negativity either.

An explanation for a behavior is not an excuse for it. Likewise my synpathy for the frustrations that led to someone else's behavior don't make the behavior right.

There's nothing wrong with his behavior. He's an adult, and he can speak candidly. He needs no permission to rant or use foul language.

Re: Is it just me or is networking really hard?

#170

Post by angersock »

ggambetta wrote: post #58
exDM69 wrote: post #23

Earlier quoted context omitted.

To be fair, Gaffer's original articles are well written, thoughtful and informative too. This is him ranting about the unfounded, negative and incorrect feedback he's been receiving about them from people who are willfully ignorant about networking. He could or should have replied with less attitude and more facts, though. I understood what and why he's saying what he is, but I didn't enjoy the negativity either.

His articles are excellent , and I've learned a lot from them myself. But I cannot sympathise with lowering the level of a technical discussion to personal insults.

I don't know if this is a general failing of people's critical thinking abilities, a sloppiness in their reading, or something else, but I have noticed over the past (feels like) few years a growing problem:

A lot of folks conflate personal insults ("you, ggambetta, are clearly a dunderhead when it comes to reading comments") with general sentiments about a group or abstract population ("Hacker News posters tend to be overly sensitive to the point of being crybabies").

A great deal of the flavor and comedy in writing, especially pieces that are self-identified rants, are not from personal insults but instead from hyperbolic and sometime vitriolic statements about an abstract other.

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