How many concurrent sessions can the NAT box handle?
The NAT box has 2 MB of DRAM. This allows over 10,000 simultaneous connections, more than most companies ever need.
Does my internal addressing scheme matter?
It generally does not. The addresses assigned to the devices behind the router are never seen on the Internet. The only exception is outlined below.
Why can't I reach certain sites?
If you have randomly chosen your IP addresses, or have moved from another provider, the addresses you are using may be registered to another network. Although there is no broadcasting of the addresses on your network, if you try to reach a network using the same addresses, you will not be able to contact those hosts. This is a limitation of TCP/IP and can only be fixed by renumbering your LAN. This is why G4 Communications recommends you select from the reserved addresses (see RFC 1597) designated for this purpose.
What about the services I host internally, such as e-mail and web hosting?
With either classic or masquerading, these situations can be accommodated. A table is built in the NAT box to indicate what addresses and port should be redirected to internal addresses. Our Technical Assistance Center (TAC) can handle these configuration changes. The TAC can be reached at 1.888.840.4487.
What is the difference between classic NAT and masquerading?
Classic NAT uses a one-to-one scheme. One registered external IP address is mapped to one internal unregistered (nonroutable) IP address. Masquerading maps one registered IP address to several unregistered (nonroutable) IP addresses.
Will my Microsoft NetMeeting and PPTP (point-to-point tunneling protocol) work?
Yes, but you will only be able to make NetMeeting calls, not receive them, because the calling computer won't know the address of the receiving computer.
I have multiple mail or web servers, can I get punch-throughs for these?
Classic NAT handles these as single servers. Masquerading requires you to have the mail or web server listen on a different port. An alias can be created to represent this port. Consult your server documentation to see if the listen port can be changed. Our Technical Assistance Center can handle these configuration changes at 1.888.840.4487.
How does NAT make my network more secure?
NAT maps the IP addresses to the unregistered ones behind the NAT box. This prevents others from being able to identify your IP numbering scheme on your LAN. With masquerading, there is only one IP address and the PCs use different port numbers to access the Internet, providing greater security.
