Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Can you separate or pass through an external IP through a Cisco 1841 to an internal device?

Ok here is the story/setup

Our bank is required to do disaster recovery testing. We are doing this offsite at one of our director's businesses. His setup is as follows:

His ISP is Time Warner which provided him with a wall unit and a switch

He has a Cisco 1841 router out from the Time Warner switch and then down to his internal network, so TW wall unit --> TW switch --> Cisco 1841 --> internal network.

The IPs provided to them from TW are 74.219.xxx.1-254

We are trying to use the external address of 74.219.xxx.222, which his business is not currently using internally

The Cisco 1841 router holds and NATs all of these addresses currently. We have a Cisco 800 series that is a dedicated router that needs an unused external static IP setup separate from their network. We were trying to plug into their Cisco 1841 and give the 800 series an internal address of 192.168.xxx.222. This will not work for our bank's core processing data center. It has to be out of the TW switch and have an address of the 74.219.xxx.222.

We tried plugging into the TW switch and making the 800 series router parallel to the 1841 router. Communication is not functioning when set up this way. This was tried on a laptop before using the 800 series router. Is there a way to pass through the 74.219.xxx.222 address internally through the Cisco 1841 so we can connect the 800 series directly to this address and the 1841 doesn't use or NAT it in any way?

We had contacted TW support and they made it sound like we would have to block out some addresses and resubnet our director's network. This probably will not be an option. Basically we need to pass the 74.219.xxx.222 addresses internally and have the Cisco 1841 pretend not to see it at all.

So we would like to have 74.219.xxx.1-254 into the TW wall unit --> TW switch --> Cisco 1841 --> all 74. addresses resolved to 192.168.xxx.1-254 to internal EXCEPT 74.219.xxx.222 which would pass through to the Cisco 800 series router.

Is this possible? Any help is appreciated. Thank you.

Eric

2 REPLIES
New Member

Can you separate or pass through an external IP through a Cisco

Hi,

I see a work around for your problem. Jst create 2 sub-interfaces on the LAN side of the Cisco 1841. use one as your LAN as you are using it currently and use another one to bridge with your WAN interface to simply forward traffic between WAN and BVI interface.

This should solve your problem.

Regards,

Pawan Sharma

http://www.ebrahma.com

Hall of Fame Super Gold

Can you separate or pass through an external IP through a Cisco


I see a work around for your problem. Jst create 2 sub-interfaces on the LAN side of the Cisco 1841. use one as your LAN as you are using it currently and use another one to bridge with your WAN interface to simply forward traffic between WAN and BVI interface.

Subinterfaces on LAN ???

Have you been trying this, or speaking in theory....

The OP problem is not so simple to solve.

602
Views
0
Helpful
2
Replies
CreatePlease login to create content