Connection Sharing and Router Nat_ routers, switches

Today, the proxy server crashed, after all, no shutdown work for a long time, with the Win2003 connection to allow the internal LAN PC access to the Internet, units of more than 40 computers through 2003 of the share connection, the basic use is very normal, that is, some of the FTP server can not connect, 2003 did not make any access restrictions, has been very puzzled, today just the proxy server strike, by the way let him rest, put a quidway2621 router to change, the simple configuration of the port, router rule NAT, access to the Internet than proxy Server fast a lot, or the forwarding speed of the router is good, and, usually not normal connection of the FTP server, now also good, can be normal connection!
By the way, check out the specific definitions and differences between ICS and NAT:
What is ICS
ICS, the English abbreviation for Internet Connection Sharing (Internet Connection sharing), is an Internet Connection Sharing service that Windows systems provide for a home network or a small intranet network. It is actually equivalent to a network address translator, the so-called network address converter is when the packet forward transmission process, you can transform the data packet IP address and TCP/UCP port and other address information. With a network address translator, computers in a home or small office network can use a private address, and a network address translator converts a private address into a single public IP address assigned by the ISP to connect to the Internet. The ICS method is also called an Internet conversion connection.
What is NAT
NAT is the network address translation (network addressing Translator), and in the broadest sense, ICS uses a NAT technology, but the NAT we're talking about here is the IP router that will run Windows Server. It enables the sharing of the Internet by forwarding packets between the LAN and Internet hosts. Nat is also known as a routing connection to the Internet. The network address translation nat hides the internal managed IP address by converting the private internal address to a public external address. This reduces the cost of registering IP addresses by using unregistered IP addresses internally and converting them to a small number of externally registered IP addresses. It also hides the internal network structure, which reduces the risk of an internal network being compromised.
The difference between ICS and NAT
Speaking of this seems to confuse people, then what is the difference between the two? In the Windows 2000 Help file, ICS and Nat are known as the Internet's conversion connections and routing connections, and in fact, it's a simplified version of NAT that uses ICS without understanding IP address and routing knowledge, and provides a local area network with Windows 2000 routers share a simplified configuration of the Internet, but ICS may not allow all IP traffic between LAN and Internet hosts, such as multiplayer games such as Diablo, real-time communications and other peer-to-peer services, If you use a private address on the public Internet or use the same port number at the same time, the applications are aborted. The NAT configuration requires knowledge of IP address and routing configuration, which is more complex than ICS, allowing all IP traffic between the LAN and Internet hosts. In addition, ICS can only use a legitimate public IP address, and NAT may use multiple legitimate public IP addresses provided by the ISP for client sharing by configuring the address pool.