Alex:

Thanks for your reply. I think the following information further clarify my
earlier question:

(a) My network is for Dial-In customers only. In that case, is there any
problem if I use private addresses for ARC & NMC?

(b) I do have sufficient IP (255) addresses to use for Dial-In customers.
But using private IP addresses make it easy to program 3Com Chassis. I can
assign a private IP address to all modems whereas right now I have to assign
IP addresses to only 4-T1 (96 modems). I want to design the setup whereas
3Com Chassis might be located behind a firewall. The firewall server can
translate the private IP addresses to public IP addresses via masquerading.
This way if tomorrow, I switch the carrier providing the T1 & block of
public IP addresses, I have no changes to 3Com Chassis.

Do you get the picture? I will be more than happy to send a diagram
(Powerpoint) if somebody wants to further criticize my design.

Thanks again.

-----Original Message-----
From: alex [mailto:alex@wanex.ge] 
Sent: Tuesday, September 09, 2003 5:50 PM
To: Discussion relating to the 3Com/US Robotics Total Control modemsystems.
Subject: Re: [USR-TC] 3Com TC IP Numbering??

Hello Kirti.

1: You can assign private address for your arc, but for example
it wont be able to send icmp-destination-host-unreachable if
ip from dial-in pool is not used (this icmp packet with private
source address wont reach its destination). You can always limit
access to your arc with access-lists (better to do it on border routers
in your network).

You can freely set private address to NMC. Only you use it.

P.S. Don't forget to limit telnet access to your arc by
"add telnet client <ip/netmask>" and "enable telnet client_access".

2: Dial-in clients: if you have lack of public ip addresses you must
assign them private addresses and then translate to public. In other
cases I dont think that it's good idea to assign private addresses to
dial-in clients. You can protect your public ip pool for dial-in users
from outside internet with access-lists, both on arc and on border
router, closing some ports (netbios over tcp, proxy, telnet, ports used
by some worms/viruses, etc).

----- Original Message ----- 
From: "Kirti S. Bajwa" <kbajwa@tib.com>
To: <usr-tc@mailman.xmission.com>
Sent: Wednesday, September 10, 2003 2:12 AM
Subject: [USR-TC] 3Com TC IP Numbering??