On Sat, Mar 2, 2013 at 2:25 PM, Brian Wood <woodbrian77 at gmail.com> wrote:

> I understand that UDT isn't part of the kernel, but am not
> sure why you disagree with the term replace.
> Here's an exchange I found on a forum.  The UDT author
> replies to the question with 3 paragraphs.
>

OK, brief networking stack lesson here.

IP, the basis for all of these technologies, is a Layer 3 protocol.
TCP and UDP are both built on IP. They are Layer 4.
HTTP, SSH, SMTP, DNS, etc. are all built on TCP or UDP. They are Layer 7
(application) protocols.

So, when dealing with say HTTP, you're not *only* using HTTP, but you're
also using each level of the stack below that the protocol was built on. In
the case of HTTP, the stack goes something like HTTP/TCP/IP. For DNS, it's
DNS/UDP/IP.

Likewise, for ODT, the stack is ODT/UDP/IP, as the quote below from the
author specifies.

To reiterate, ODT is not a replacement for UDP. Rather, it is an
Application Layer (Layer 7) implementation on top of UDP.

http://en.wikipedia.org/wiki/OSI_model

"Can you provide some data on how the protocol overhead
> compares to TCP?"
>
> The UDT packet header is 4 bytes longer than TCP
> (UDT/UDP/IP headers vs TCP/IP headers). Since UDT is at
> user space, it uses more CPU (up to 2x, especially at low
> throughput: the design of UDT makes it more efficient at
> higher throughput) and also likely more memory buffers
> are required (exact number is application specific but
> usually it should not require significant more buffers).
>



> I'm also thinking about using nginx instead of apache.
> From what I've read --
> http://blog.zhuzhaoyuan.com/
> nginx is faster with static pages and that's all I have
> at the moment.   Nginx is smaller in terms of disk space
> so that's in its favor.
>

Excellent choice. I've been a die-hard apache fan for most of my sysadmin
years, but have switched nearly every system I can over to nginx in the
last six months, and couldn't be happier.

-Erik
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