Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

NATing

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080094837.shtml

The link above is to Cisco's webpage for "NAT: Local and Global Definitions." I have a question about the section where it talks about "Define Outside Local and Outside Global Addresses."

When the NAT router translates the outside global address from 171.16.68.1 to 10.10.10.5 (the outside local) the host 10.10.10.1 would think the packet was sourced from the IP 10.10.10.5 since that's the SA it sees in the IP header. When it went to reply it would use a destination address of 10.10.10.5. Here's my issue, wouldn't the 10.10.10.1 host based on the adjacency test believe that 10.10.10.5 would be on it's own network so it wouldn't send the packet to the router but would instead attempt direct delivery? To me this would seem to break the communication. Am I missing something here?

TIA,

Brad

I've included the pic from the webpage.

1 ACCEPTED SOLUTION

Accepted Solutions

Re: NATing

When 10.10.10.1 puts out an ARP request for 10.10.10.5, the router would respond with its own MAC address because it knows it is acting on behalf of 10.10.10.5.  So subsequent packets would be sent to the router.

Kevin Dorrell

Luxembourg

2 REPLIES

Re: NATing

When 10.10.10.1 puts out an ARP request for 10.10.10.5, the router would respond with its own MAC address because it knows it is acting on behalf of 10.10.10.5.  So subsequent packets would be sent to the router.

Kevin Dorrell

Luxembourg

New Member

Re: NATing

Thanks Kevin, that makes sense.

415
Views
0
Helpful
2
Replies
CreatePlease to create content