12 Jul
2004
12 Jul
'04
12:39 p.m.
--On 10 July 2004 23:59 +1000 Zeus Ng <zeus.ng(a)isquare.com.au> wrote:
Can you redraw your diagram and place ser in the path
as well. I don't
understand what you are trying to illustrate.
10.0.0.1 A -> NAT1 -192.168.0.1 \
|--> NAT3 --> 195.1.1.1 Internet -> Ser
10.0.0.2 B -> NAT2 -192.168.0.2 /
Personally, I've tried UAs behind two / three
layers of NAT and it works,
if it's what you are trying to say.
Yes, there are situations where the logic break. Mostly, if one UA is
behind two NAT, one inner and one outer. The second UA is behind the same
outer NAT. As a service provider, it's not my problem. My logic perfectly
handles the outer NAT. As for the inner NAT, the client has to figure it
out internally.
Indeed - I was trying to illustrate a situation where the two UAs
are behind the same outer NAT but not behind the same inner NAT. As far
as I can see the test uses the heuristic that the UAs are behind the
same LAN if the packet source/dest IP (i.e. routable addresses) are the
same. This heuristic fails when they are behind the same outer NAT
(same routable IP) but not behind the same inner NAT. It also fails
in circustances like this (AFAICS):
10.0.0.1 A -\ 10.0.0.0/8
|
| 195.1.1.1/24
NAT ---------------> Internet -> Ser
|
|
192.168.0.1 B -/ 192.168.0.0/16
i.e. where you have a dual-private-ported NAT (for instance a corporate LAN
and a lab LAN) with the same external IP.
Alex