Discussion on:

Set up NAT using the Cisco IOS

We've been using NAT with the Cisco IOS for about a year now. It works very well and made our last ISP switch much smoother. When we switched IP ranges we only had to make a few changes to the router instead of modifying each machine within the network. The only thing I am still curious about is the performance hit NAT adds to external access. Does anybody have any knowledge they would share on that point?

We recently installed basic 256K DSL from Qwest in Chicago at two small (5 PCs) LANS. Qwest uses a small Cisco 675 (or 678) DSL modem with DHCP & NAT capability as part of their package. One office has a Cisco 806 router and a bloc of (5) IP addresses, but we're only using NAT there now via the 806 setup. The other office just uses the NAT/DHCP of the 675 device.
*** BOTH SITES HAVE SEVERE LATENCY ISSUES ***
*** BOTH CLIENTS ARE DISSATISFIED WITH THIS**
The time dealys after a click before there are any signs of data flowing are 3-10 seconds typically. The 56K modem would complete many things faster than the 256K DSL. Bypassing the 806 router & using live IP addresses immediately gave a spped boost & latentcy disappeared at the onesite. The NAT may not be the problem, it may just be Qwest's network that is causing this. We've had great results using NAT with with McLeod DSL & Netopia routers. Qwest is trying to weasle out of responsibility.

we use two Cisco 827 routers to provide a VPN between two sites and Internet access independently at each. There is no speed issue for us. The only problem being sometimes the ADSL goes down at one of the sites but this is due to the telephone providers.

nice easy tutorial, except for command explanations part
You should've explained that with examples.

Sir I would like to thank u first for providing us this NAT config on cisco and explaining it
for those who configures it first time it is very difficult so please gieve me this be taking one static so ip address and lan ip 192.168.1.0
please sir i have been waiting for ur kind reply
thanks

check where you've placed your labels on your diagram.

your circles should be "local" and "global" ... not inside/outside

and your host labels should be from left to right:

inside local, outside local, inside global, outside global

(it makes more sense to me that way... others may disagree...)
Eitherway your "web server" should be "outside global"

check it out here:
http://www.cisco.com/warp/public/556/8.html

We trying to use the NAT outside to replace the alias. But i can't get it work.

We have a server in office. It has external IP point to its internal IP on PIX510 firewall settings. Before we use alias to let office user access its external IP. Now we want to use the NAT outside.
However after I set the

static (outside,inside) 192.168.0.157 209.190.xxx.xxx netmask 255.255.255.255
conduit permit ip xxx.xxx.xxx.0 255.255.255.0 xxx.xxx.xxx.0 255.255.255.0

it doesn't work. Any idea?

Thanks

HI,
I have a situation. I need to configure the router like only one inside local ip will be transtaled when it send packet to any selected local host. And also when that outside local return the packet it will also be translated with the outside global address of the router. is it possible?

I also have an issue with my NAT connection, I have done the needful according to the configuration above, but I cannot ping the internet.
Brief explanation, we were given a pool of private IP addresses by ISP which has already been NATted on their own network. Is it advisable to NAT to these addresses to prevent ambiguity in configuration?
After I NAT into these address pool, I can ping the modem from my client PC and can see the translations using the "sh ip nat trans" but I cannot ping any external internet address.

Pls advice.