ip nat outside does not work on fast ethernet

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Jun 23rd, 2008
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I am having a cisco 2800 series router.

I am having ISP link with RJ45 termination which i can connect on an ethernet interface. when i am trying to connect it on the FE port of the router with IP nat outside command on FE then it stops working. but on firewall it is working perfectly. Can anybody give solution how to make it work on the router with NAT configured on the router.

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paolo bevilacqua Mon, 06/23/2008 - 02:46
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Please paste here the ACL used for "ip nat inside source". If it is of the type "permit ip any any" that is causing you problem, you should change it so to include only internal source address in ACL.

Hope this helps, please rate post if it does!

rohan.jhaveri Mon, 06/23/2008 - 12:34
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Does the link come up when connected to ethernet port of router?If not,then its because the Cisco 2800 series has GE port and MEN links from ISP are for FE port.

The link may come up on firewall as it may be having a FE port and not a GE port.

For all you know NAT may not have any role to play if link is not UP.

Correct me if my understanding of your question is not right.

paolo bevilacqua Mon, 06/23/2008 - 12:41
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Rohan, speed on router ports is not an issue, because these do work 10/100/1000 as desired. Beside, only bigger ISR router have gigabit, the smaller have 10/100.

The question however is poorly formulated and got no follow-up, thing that generally indicates the issue has been resolved but the person did not bother informing about here.

foxbatreco Mon, 06/23/2008 - 19:15
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Bevilacqua's point is correct enough, port speeds are not the ones causing issue here.

Most probably ACL defined for NAT purpose is causing the problem here.

lets wait for the poster to revert back.


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