

Digging Deeper Into The Cloudflare CDN - becomevocal
http://www.zingcheckout.com/blog/2012/2/4/digging-deeper-into-the-cloudflare-cdn/

======
sargun
The biggest thing that companies miss when they're building SaaS applications
is that the network fucking matters. I'm talking from a internet-connectivity
perspective. The view here is that you can take any ol' 'enterprise' ISP and
put your servers on it, and you'll be good to go.

Unfortunately, no two ISPs are equal, which often times, forces you to
purchase from both. TCP implementations of OS's today have been tuned for the
late 90s, which requires dives under the hood to tune them for today's TCP.

When your application performance is pegged on the network the, most people
say just put static content on a CDN - and that works. But for dynamic
content, most people think you're screwed. While you can't main any gigantic
gains on it, there are a few things you can do for speed: TCP tuning,
compression, path optimization, and pipelining.

~~~
Terretta
> _TCP implementations of OS's today have been tuned for the late 90s,_

Here's where you need to slow down and think for a moment before you re-invent
TCP.

If you "retune" everything for broadband, you're crippling your ability to
reach your emerging mobile audience, whose TCP metrics look for all the world
like dial up and ISDN of the late 90s.

~~~
moe
Actually they don't. Dial-up is low bandwidth, low latency. Mobile is high
bandwidth, high latency.

~~~
Terretta
Dial up is low latency when a modem adds 200 ms by itself?

Mobile is high bandwidth when an EDGE connection might pull 110 Kbps when the
rural user is lucky?

Either you're confused, or talking about different tech.

~~~
moe
_Dial up is low latency when a modem adds 200 ms by itself?_

Closer to 100ms and, more importantly, constant not variable.

 _Mobile is high bandwidth when an EDGE connection might pull 110 Kbps when
the rural user is lucky?_

The fastest modems sold were 56kbps.

~~~
Terretta
I had ISDN in the 90s, at dual 64k.

Was in ISP business since early 90s, and in streaming business since before
broadband, so familiar with connection profiles, latency, and effects of
tuning TCP. There's a lot of lost or forgotten art being reinvented or
rediscovered for today's mobile.

------
XERQ
We disabled Cloudflare after a month because of their awful nLayer routing. We
were getting complaints of slow accesses from Telia customers in Europe. Now
we're back with SSD Nodes and much happier with SoftLayer's peering and
transit connections (they peer directly with Telia).

Your mileage may vary.

------
pcouture
Most large players in heavy load content ( like live video streaming ) run
double failover systems these days. Even if your running systems on S3 piping
it through Akamai, you can't guarantee that they won't drop you when your load
gets too high. So you have to setup a sister chain going through another
origin and cdn.

But even at that if you start talking 100k+ clients you can't offload them all
at the same time so you end up having to create this custom origin/mid tier
distribution system...

Very annoying. I'd like to see CDN's being held liable if they go down or drop
you entirely.

~~~
Terretta
I'm not aware of any real CDNs dropping someone for "load getting too high".
Also, for a real CDN, 100k+ clients isn't noticeable.

If you're talking about the "unlimited traffic" or "price too good to be true"
commodity delivery resellers, their business models are sometimes built on
overselling and like a cell provider, those will throttle or drop you.

That said, a "network of networks" is a great strategy beyond a certain level
of traffic. Nine Systems built a great business on that principle for video
streaming until purchased by Akamai. Balancing video over multiple CDNs is a
service we offer as well.

Finally, if your CDN SLA doesn't hold the CDN liable for going down, you're
doing it wrong.

~~~
moe
In video-streaming 100k+ clients equates to 25+ GBit/s. Yes, that is
noticable, even for a "real CDN".

------
bcl
I trid out CloudFlare for a few months for a couple of my sites. I was
primarily interested in their 'no downtime' feature but could never get it to
work for me. I ended up swtiching to S3 and CloudFront, paying a little each
month but it actually works.

~~~
oldstrangers
Their no down time feature is just them holding a cache'd copy of your site.
It could technically not work for you and still work for someone else.

------
ebaysucks
Now I know where those annoying challenge pages come from. Was planning to add
CloudFlare to my site but if it comes with those challenge pages, I'd rather
pass.

~~~
ddorian43
i believe those are optional

~~~
vnuk
Challenge pages cannot be totally disabled. From CF's admin page:

Adjust your basic security level to modify CloudFlare's protection behavior. A
low security setting will challenge only the most threatening visitors. A high
security setting will challenge all visitors that have exhibited threatening
behavior within the last 14 days. Essentially off will act only against the
most grievous offenders. We recommend starting out at medium.

