Basic Question

[Lost2M8]

Question:

I have just started a new job....

We have a Cisco 2800 series internally (behind a pix, but offsite). Now for some reason the internal LAN IP (e0/0)is not a valid internal IP (IE 212.212.212.x) but the e/01(WAN) is a valid internal address (192.168.100.1).

Now I of course want to change the LAN address from 212.212.212.1 to 192.168.100.2 but is this proper standards? In my previous job our external would be x.x.100.x and LAN ip would be x.x.101.1

Hopefully someone understands me....

Thanks in advance.

 

[brianinms]

I wouldn't recommend you change anything until you understand that routers functionality completely. Is your local network 212.212.212.x? Post a copy of the config.

 

[Lost2M8]

I can post it tomorrow. I am obviously not doing anything for a few months but the all the routes use the correct WAN addresses.

There are 6 sites. Each site has a 2800

1. LAN IP 212.212.212.x WAN IP is 192.168.212.x
2. LAN IP 212.212.213.x WAN IP is 192.168.213.x
3. LAN IP 212.212.214.x WAN IP is 192.168.214.x
4. LAN IP 212.212.215.x WAN IP is 192.168.215.x
5. LAN IP 212.212.216.x WAN IP is 192.168.216.x
6. LAN IP 212.212.217.x WAN IP is 192.168.217.x

All I am wondering is can the LAN be the same subnet. So say E0/0 is 192.168.212.1(WAN) and the E0/1 (LAN) be 192.168.212.2 or should I use a different IP such as 192.168.222.1 for the e0/1 port.

I know I will have to change all the statics inside the LAN, update the DNS server, change the port forwarding IPs (yes i know I have a lot of planning!) but this will help me start planning my addys.

 

[Lost2M8]

Oh and I should add they are behind a sinlge pix firewall.

 

[burtsbees]

Looks like a T1, with ptp vpn's...

Burt

 

[Lost2M8]

Thanks Burt?? I can tell u the technology coming in and between each site....that has nothing to do with the question.

 

[burtsbees]

If you say so...I mean, the fact that you have 6 public IP addresses INSIDE for public access and privates on the WAN for interlan comms has NOTHING to do with the fact that this is how T1 technology is sometimes handled...change it if you want to, then...NAT everything to one public IP on the outside...what can I say? But thanks for pointing that out...

Burt

 

[Lost2M8]

Incase you missed the top, I just started here. I never implemented those addresses. I know I can make it anything I want and NAT, I am asking if there is a common standard for this.

 

[burtsbees]

It seemed that you were asking why the addresses seemed to be reversed, and I was merely pointing out that this is one way to do it. I mentioned what the technology looked like in the hopes that you would confirm/deny---that is a starting point.
I have seen it done this way because it seems people want to have public IP addresses for their FTP/

http://WWW servers

and what-not rather than NAT them. Sometimes people like to see this as not wasting their 6 addresses that come with the T1. Myself---I have the same, and I NAT to one address. It seems safer this way...

HTH

Burt

 

[Lost2M8]

Thanks Burt, appreciate the help.