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Cisco 1841 for Intenet

Dear All,

I HAVE cisco 1841.

it has 2 interfaces.

the first one which is f 0/0 is have public ip from my ISP.

the other one is normal, and i am going to give it / 24.

now i have 3 subnets totally diffrent .

i want to create 3 subinterfaces from f0/1.

my question is , how many subinterfaces can i add under the f 0/1 ?

and can i make this Router work as NAT ( overloading ) but all the 4 subnet will use the same public IP Address ?

can it be done as per this diagram ?

please update me.


Re: Cisco 1841 for Intenet


it can be done. a few notes though.

your F0/0 interface will not have an ip address on it. (only the f0/0.1, f0/0.2..etc)

if you use subinterfaces, you only put ip addresses on those.

(likewise, if you do not use subinterfaces, you would put an ip address on F0/0)

you can then enable NAT to provide internet acceess for all of your subnets. you will create a nat pool that all subnets are assigned too and then use an 'ip nat inside source list....overload' command. see the link below for an more NAT info:

also, you can configure a subinterface for each VLAN you need to configure.

(since your interface will be supporting multiple vlans, it will be using 802.1q and the switch port it connects to will have to be configured as a 802.1q trunk as well)