PAT with static NAT on same interface

[imanassypov]

Hi All,

Does having the following configuration on an ios device present any possibility that an egress stream PAT'ed to loopback gets source port translated to the statically nat'ed port?

interface Loopback0

ip address y.y.y.y

ip nat outside

ip nat inside source list acl interface Loopback0 overload

ip nat inside source static tcp x.x.x.x 7062 y.y.y.y 7062

For example, egress private ip address getting pat'ed to the loopback, eventually will have its source port translated to the '7062' in this case. How does the IOS route the return packet vs a new stream hitting the y.y.y.y on the same port?

thanks!

[johnlloyd_13]

hi,

i haven't encountered a loopback interface used for PAT. you should set the WAN physical port as the NAT outside interface. loopback interfaces are usually used for device management purposes.

[Marwan ALshawi]

well loopback interface sometimes can be used for some unconventional NATing cases such as NAT on stick, but you need to use PBR with it

see the bellow link:

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094430.shtml

not sure in your case what you trying to achieve !

hope this help

[johnlloyd_13]

hey marwan,

nice link! good to know this exist