[Jool-list] BIB-less NAT64

[Tore Anderson]

* Alberto Leiva <ydahhrk at gmail.com>

> > The reason I'm asking is a «problem» I've seen with Jool's NAT64:
> > it can only handle 2^16 * $number_of_addresses_in_pool4 concurrent
> > connections (per protocol).  
> 
> Are you sure?

For all practical purposes, yes.

> You're making it sound like you can only have as many connections as
> the maximum number of BIB entries given your pool4. If this is truly
> the case, this is a bug. Each BIB entry should be able to have
> multiple sessions, and each session should represent a connection.
> 
> Of course, every one of a BIB's sessions must share client v6
> transport address ("IPv6 Remote" in Jool's -sd output) and pool4
> transport address ("IPv4 Local"). But AFAIK this is a limitation of
> NAT64 itself, not just Jool's.

An IPv6 client source address:port tuple will in normal circumstances
only be used for a single connection. If the client creates a new
connection through the NAT64, it will use a new random source port, and
thus be allocated a new BIB entry. For this reason, the BIB and session
tables end up having almost exactly the same amount of entries:

root at nat64gw1-osl2:~# jool --session --count
16916
27
55
root at nat64gw1-osl2:~# jool --bib --count
TCP: 16832
UDP: 27
ICMP: 55

> Okay, guys. Prototype ready.

Alberto, are sure you are human?

> Experimental branch in fake-nat64, in case anyone wants to try it out:
> https://github.com/NICMx/Jool/tree/fake-nat64

I would like to. My schedule the coming few weeks are totally swamped
though, so it will probably not be until October until I have time...

> This thing makes mask-choosing trivial. It's way faster than a stock
> NAT64.

...but I suppose this might make Sander want to give it a go
instead. :-)

Tore