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New Member

changing destination address?

I need to get a router to change the destination IP address of packets. WHen somebody sends a packet from 10.x.x.1 to 209.x.x.1 I want an internal router to route that packet to a computer at 10.x.x.2. I tried the IP route commmand and the 10.x.x.2 computer didn't know what to do with a packet going to 209.x.x.1. I also thought about nat, but that changes the source address not the destination. Can anybody point me in the right direction? Thanks in advance.

Jpoulos

CCNP

3 REPLIES
New Member

Re: changing destination address?

It sounds to me like you have an internal device (10.x.x.2) advertised to the outside world as 209.x.x.1 via DNS. When an inside user querries DNS for the address to the host name of 10.x.x.2, DNS returns the 209 address. This causes internal users to try to hit 209.x.x.1 which is probably being NATed to 10.x.x.2.

Did I get the problem right?

If your DNS is internal, you need to change the DNS entry to the internal address (10.x.x.2) and allow NAT to change the DNS packet payload to 209.x.x.1. This way, your inside users will hit 10.x.x.2 directly.

If you DNS is external, you may have to use NAT on a stick. Check with TAC on some good examples for this since it can be tricky.

Hope I got this one right.

Mick.

New Member

Re: changing destination address?

Thanks for the response. My real problem is more complicated. I am using polycom Viavideo cameras internall and externally. You manually assign the ip address for the camera. When I call someone external I want my camera to have an external address 209.x.x.1(using conduit to come back in), but if I then call someone internal my camera still has external address assigned. I want my router to see this the reply from the other internal camera going to 209.x.x.1 and send it to my internal address 10.x.x.1. I tried the ip route statement but my computer doesn't know what to do with a packet sent to 209.x.x.1. Polycom acknowledges that this is a bug in their software.

Jpoulos

New Member

Re: changing destination address?

Sounds like NAT on a stick. It can be pretty tricky and it also varies depending on the release of IOS for your router.

I would call TAC and ask about this. They have some good config examples of it and they can help you troubleshoot it on the phone.

Mick.

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