nat pool question

Unanswered Question
Jun 18th, 2009

Hi all!

This are my nat staments,

ip nat inside source list 111 ROUTEMAP_NAT pool publicips

ip nat pool publicips prefix-length 24


This is a pool of 254 IPs but i have 500 host, if the 500 host try to access internet at same time, the router could translate the 500 streams or when reach last IP from pool drop connections until one timeout?

And, if the maximun is 254 translations, how can i overload all my streams?

Thank you in advance.

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John Blakley Thu, 06/18/2009 - 08:15

You should be able to put the overload keyword at the end of your source line. It will enable PAT.

ip nat inside source list 111 ROUTEMAP_NAT pool publicips overload

Oh, and are you using an acl or a Routemap?



*Please rate if it helps*

david.knet Thu, 06/18/2009 - 08:17

I tryed that but then allways the source ip is the first of my pool and i dont want this.

david.knet Thu, 06/18/2009 - 08:23

I am doing load-balancing per-destination and if the source ip is allways the same then the traffic flow allways by the same path

John Blakley Thu, 06/18/2009 - 08:36


You could try:

ip nat pool publicips prefix-length 24 type rotary

This would rotate through your ip addresses. You could also try (although this should be tested):

ip nat inside destination list 10 pool publicips

The problem with the above is that I'm not sure if it overloads. And if this is for internet traffic, your access list may need to look like:

access-list 10 permit any

I'm going to lab this and let you know. I'd be interested in seeing if it works as well.



Collin Clark Thu, 06/18/2009 - 08:40

If I remember correctly, each unique internal IP will use a unique public IP until the last public IP ia available and the rest of the clients will be PAT'd out of it. I'll see if I can find some docs on it. You original post config looked OK for this.


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