Jon:
The absence of the use of the "extendable" keyword in your example leaves me with questions.
First, I'll paraphrase what I believe I've understood, and then I'll address the scenario I have questions about.
It appears that you are saying that the following won't work:
Exhibit A
ip nat inside source static tcp 192.168.10.26 aaa.0.0.136
ip nat inside source static tcp 192.168.10.26 bbb.0.0.136
... that it should be configured as:
Exhibit B
ip nat inside source static tcp 192.168.10.26 aaa.0.0.136 extendable
ip nat inside source static tcp 192.168.10.26 bbb.0.0.136 extendable
... to generate full un-ambiguous translations.
The following two statements are understood:
- For a new outside-to-inside flow, the appropriate static entry will act as a template for a full translation.
- For a new inside-to-outside flow, the dynamic route-map rules will be used to create a full translation.
However, your earlier post stated:
"This would allow you to map two local addresses to the same global address on different ports."
In a NAT overload scenario:
Presumably this would not work (less than full translation):
Exhibit C
ip nat inside source static tcp 192.168.0.100 aaa.bbb.ccc.ddd 80
ip nat inside source static tcp 192.168.0.200 aaa.bbb.ccc.ddd 21
... however, I am wondering if this:
Exhibit D
ip nat inside source static tcp 192.168.0.100 80 aaa.bbb.ccc.ddd 80
ip nat inside source static tcp 192.168.0.200 21 aaa.bbb.ccc.ddd 21
.... is any different than this:
Exhibit E
ip nat inside source static tcp 192.168.0.100 80 aaa.bbb.ccc.ddd 80 extendable
ip nat inside source static tcp 192.168.0.200 21 aaa.bbb.ccc.ddd 21 extendable
... which, much like Ismail884's example:
ip nat inside source static tcp 192.168.10.26 21 79.29.20.136 21 extendable
... looks redundant to me.
I don't see the need for the extendable keyword here. It looks like the extendable keyword is the redundancy, and not the port specifications.
I'm not trying to prove anyone wrong, or split hairs. It just felt like I was missing something when I started this reply (its taken a while to compose), and have arrived where I am now.
