Question about loopback network interface

["Adam McLaurin" <lkml@irotas.net>]

Hi,

I am looking for some information on how exactly the loopback network
interface works. I've done a fair amount of Google/StackOverflow
searching but haven't really found anything particularly useful.

In particular, I'm interested in 2 things:

1) A diagram of the 'plumbing' of what exactly happens when an app
communications with another local app using TCP

2) How "loopback-aware" is TCP (the implementation in Linux, not the
protocol in general)? For example, does congestion control still come
into play when communicating over loopback? Or does TCP always do the
same thing, regardless of whether it's communicating to a remote or
local app?

Thanks,
Adam

P.S. My apologies for cross-posting this email with linux-net - I looked
at the recent archives of that list and it seems like nothing but spam