Question regarding private IP addresses.

[Wyckyd1]

"Private IP address for router Why can't they just use what is already in place?"
Hi,
I am not a Cisco person or a router person or even an experienced WAN person so I need to know the answer to this. It may be more off of principal than "Why not do it anyway?".
There is a small office on a small LAN. The computers on the network are assigned private IP addresses via DHCP. They are class C addresses (192.168.x.x-in this case since it is a small office it is 192.168.1.x where x has some reserved addresses such as for the server and the router). So all is assigned via DHCP including the gateway address of 192.168.1.1 which is the router. The router provides NAT.
Now they are going with a company that will provide them high speed access. This company is going to put a Cisco router in. NO problem I have seen people with private IP address schemes similiar to this one and the ISP had no problem assigning the Router whatever IP address that was specified.
Well this company is coming in saying that they can only assign the router a 10.x.x.x address (Class A). They say they can't do the 192.168.x.x which would be easy because then they just replace the current router with there own and it is all seamless in theory . As I said I've seen exactly that happen before.
My question is WHY can't they just assign it the address the current one has? Yeah it is a different class but as I said this is not a WAN it is a small LAN. I was told it needed to be that way for monitoring the router. Why would a private IP address scheme on a LAN have anything to do with monitoring a router. Wouldn't they just need the routers public IP address? They are NOT permitted to enter the LAN and monitor it. So whatever is going on in the LAN is none of there business.
The person I talked to said she didn't have the exact answer but will have someone call me. So I want to be equipped. Is there a reason a private network would need the internal part (gateway address) match what the company wants (10.x.x.x) in order for them to monitor the router from the outside?
Any insight would be appreciated.

Have a great day!

[vilagefool]

ok, i am in the cisco courses now and i'm still learning. but I'll give it a shot. The 10.x.x.x address is created at the ISP by a pix box. This does the same thing as your current router. it assigns ip address and 'translates' them when traffic passes through. BTW, do you know the model number of this cisco router? You should be able to put your own ip addresses and not have a problem as long as you set it up in the router. (I am assuming that the router supports this) The only argument that your ISP might have is if the company gets support from the ISP and they need to login to somthing past the router. I hope this helps and didn't confuse you even more. I'll check up on how exactly this can be done.

[Wyckyd1]

Thanks for the reply. Yeah you should be able to assign the router any private IP address. As I said I've seen it done. They are not going to use the DHCP capabilities of the router because the server already does this. They will be using the NAT though.
So are you saying there really is no reason for the company not being able to assign it there current gateway if they don't want the ISP in there network, which I know for a fact they do not. They don't care if the ISP wants to monitor there own router but they don't see any reason thier private network needs to be viewed. So in a nutshell they should have no problem doing what they want (i.e. monitoring there router) if they keep the current gateway address rather than thiers?

[Gollo]

If you wanna get really funky your could have the router that is currently in place uplink to the router the ISP is installing but that could get funky. Who knows it might just work.

[Wyckyd1]

[quote] If you wanna get really funky your could have the router that is currently in place uplink to the router the ISP is installing but that could get funky. <hr></blockquote>
The thought crossed my mind but yeah could cause some quirkiness. Then you have another piece of equipment to suspect. I think though it is more of principle now. This ISP's salesperson told these people it would be absolutely no problem to accomodate the current scheme. (This was among other things they said as well.) Then once the contract was signed, guess what?
So my thing is: I see no reason why they can't accomodate the current scheme and unless they can give me a reason why they need thier scheme which they say for monitoring then they should accomodate thier client. So I think the thing of having thier own scheme for monitoring purposes is Bullsh8t. Maybe not though but that is why I ask. It is just hard to believe someone once they lied to you esp. lied more than once.

[silencio]

Well, I couldn't confirm this on TAC but the router that they are going to use may only use the 10.x.x.x network on the inside interface. It's not uncommon. If you use Windows 2000 internet connection sharing you need to use a 192.168.0.x network.

[Matridom]

I'd go with gollo's recommendation, just attach your current router to the ISP's router, the only issue will be an extra hop. Also believe it or not, it's easier for troublshooting. You know how your current setup works, how to troublshoot it ect.. Also if your ISP dies for whatever reason, it's easy to go to a backup connection.. minimal downtime. If you use he's recommendation, you can't change to backup ISP or anything..

[EvilCabbage]

Agreed.

[Wyckyd1]

Thanks to all for the input, very much appreciated. Just thought I'd give ya the skinny after talking to one of the "big techs" for the ISP.
Basically it is not for monitoring purposes (as I suspected also confirmed that with a CCNA), and there is no reason why the router cannot be assigned another address. He said the reason was because the ISP wanted to keep addressing schemes on all thier clients uniform, therefore if a tech gets a call from an office about a problem they will already know the IP addressing scheme. I guess that makes sense, saves a little bit of time.
I explained this wasn't what they were told. Hopefully they put that clause in the contract not just accepted it in the write in I put in thier "list" of things they need to do and things they will do. (That was more of a pamphlet).
As explained the ISP wouldn't be getting the first call if there was a problem anyway so he will call back and see if they can just assign the router the class c private ip address.

We'll see.

Thanks again.