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

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

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

NAT/PAT sessions


I'm designing a network for ISP, and I would like to know if a 7600 or 12000 router can handle NAT/PAT for 50000 clients. The thing is that we want to save public IP addresses, so we assign private addresses to the residential routers, and we will translate them in the Internet Gateway. I would like to know if one of those routers can handle such traffic and NAT/PAT sessions.

Hall of Fame Super Gold

Re: NAT/PAT sessions

Hi, actually you did not mentioned the speed of the link to the internet. That is the most important factor in choosing a router.

Consider each NAT entry is about 312 bytes, so for example with 1 GB or RAM you can support like 3 millions of simultaneous translations. See:

Note: currently broadband users take in serious consideration the availability of public Vs private addresses when choosing a broadband service, so do not rule out that you will need to handle public addresses at least as a premium service.

Please rate post if it helps!

Re: NAT/PAT sessions

Ya if your building an ISP I would highly recommend getting more real IP's as (at least here) you'd lose alot of customers that want real (aka public) IPs

New Member

Re: NAT/PAT sessions

Hi, i work in a Celular company from Chile, and i have a problem with a NAT/PAT, realy the problem is not with a NAT/PAT, the problem is when 10000 user consulting some webpage like; when this happens take this consulting how a attack, beacause 10000 user consulting the same webpage with the same IP address. This problem you will have too, how resolve this?.

I have a 128 real IP, but the NAT/PAT complete the 65000 port the first IP en then follow with the second IP.



Andrés Améstica U