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New Member

NAT and Networking


Je suis en projet (formation continue). Je suis en train de faire ce projet avec un collègue et nous rencontrons une difficulté que nous n'arrivons pas à résoudre.

1. Notre réseau interne (notre projet) est en réseau privé en adressage
2. Nous avons créé des VLAN avec un switch lequel est connecté au Routeur.

3. Notre réseau internet (notre projet) est connecté au réseau de notre centre de formation lequel est en 172.16.xx.xx /27. Celui ci est connecté à internet avec sa passerelle que nous connaissons bien sur. Les PCs sur les différentes VLANs arrivent à pinger la passerelle du réseau du centre de formation pour sortir sur internet ce qui est bien (c'est-à-dire que le ping atteint le routeur, sort de l'autre coté du routeur pour aller sur le réseau du centre formation et atteint la passerelle de sortie) MAIS lorsqu'on ping l'adresse de Google = KO ou autre adresse de externe (en utilisant l'adresse en décimal).

4. Apparemment le NAT est bien configuré ???? mais c'est KO donc je pense qu'il y a une erreur au niveau du NAT. ?????

Des conseils ????? ou avez vous besoin de nos config pour voir si il y a des erreurs. Note : nous sommes des débutants dans CISCO donc à voir pour les erreur de config ?? lol




Re: NAT and Networking


Would it be possible for you to post your threat in english?


New Member

Re: NAT and Networking

Oups, I thought I was on the french forum.

Well no problem - in english :

I am currently following an I.T training in networking and telecommunication. I am doing a project with a collegue of mine and we are running into a difficulty.

My project:

1. We have an intern network with network and also some VLAN,

2. We are connected directly using a CISCO router to the school network which one is on The gateway for the school is

3. Our network and the VLAN can ping up to the gateway from the school. So everything looks fine but we can't ping and not even the ip address for google.

4. We did set up NAT on the router and still KO.

So basically we can't go on the internet. As part of my project is also to install ISA 2004. I did install it on the network and used ISA 2004 as a gateway to the school network. All the computers from my network can access the internet passing through ISA. When I put the router without ISA 2004, this is KO.

Voilà. Hoping my explanation is good enough. Do you want our router config to check it out ??? we spent many days on this and this is getting annoying as the teacher don't even know themselves

I just got the config sent to me by my collegue. Here it is. Note : We are beginners with CISCO so hopefully nothing will shock you lol with the config.

New Member

Re: NAT and Networking

I believe you need to change the static route to specify the next hop not the network address

ip classless
ip route
ip route

New Member

Re: NAT and Networking

Oups, yes you are completly right on this point. I will check it out tomorrow. thanks for this.

I keep you info if there are still no access to internet or if there is.


New Member

Re: NAT and Networking

Not a problem, I used to make that mistake all the time, but since I have started preparing for my CCNA certification, I have stopped making that little mistake. Just another thing I noticed in the configuration file, you didn't configure the 2nd subinterface.

Hopefully that little mistake will fix your issue.

New Member

Re: NAT and Networking

Thanks for your reply.

The file I put there is a config which was saved on .txt and my collegue did not save the one with all the interface beeing set up but the second interface does have an address. Today is morning here in France, I will check it out when going there and get you an answer on what is happening with the changes.


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