What Is Multi-Nat - ZyXEL Communications P-2608HWL-D1 Support Notes

Ethernet (10 baseT) is the most popular interface standard for the computer to connect to the model. This
automatically limits the speed of the connection to less than 10 Mbps even if the cable modem can receive at 30
Mbps or more. Most Local Area Networks (LANs) use 10baseT Ethernet, and although they are 10 Mbps
networks, it may take longer than one second to transmit 10 megabits (or 1.25 megabytes) of data from one
terminal to another.
Cable modems on the same node share the same amount of bandwidth, which means that congestion occurs
when too many people access the Internet at the same time. In addition, when one user is downloading large
graphic or video files, a significant portion of the shared bandwidth is used thus slowing down access for other
users in the same neighborhood.
Most independent Internet Service Providers (ISPs) today connect to the Internet using a single 1.5 Mbps (or T1)
telephone line. All subscribers share that 1.5 Mbps bandwidth. Cable companies connecting to the Internet
backbone using a T1 line limit their subscribers to an absolute maximum of 1.5 Mbps.
To create the appearance of faster network access, ISPs store or "cache" frequently requested web sites and
Usenet newsgroups on a server in the central office (CO). Storing data locally will remove some of the
bottleneck at the backbone connection.
How fast can they go? Theoretically, they can receive data at speeds up to 30 Mbps. In the real world, with cost
conscious cable companies running the systems, the speed will probably fall to about 1.5 Mbps.

What is Multi-NAT?

NAT (Network Address Translation-NAT RFC 1631) is the translation of an IP address used within one
network to a different IP address known within another network. One network is designated the
outside
and the other is the . Typically, a company maps its local inside network addresses to one or more global
outside IP addresses and "unmaps" the global IP addresses on incoming packets back into local IP addresses.
The IP addresses for the NAT can be either fixed or dynamically assigned by the ISP. In addition, you can
designate servers, such as a web server and a telnet server, on your local network and make them accessible to
the outside world. If you do not define any servers, NAT offers the additional benefit of firewall protection. In
such case, all incoming connections to your network will be filtered out by the Prestige, thus preventing
intruders from probing your network.
The SUA feature that the Prestige supports previously operates by mapping the private IP addresses to a global
IP address. It is a subset of the NAT. The Prestige with ZyNOS V3.00 supports most of the NAT features based
on RFC 1631, and we call this feature as 'Multi-NAT'. For more information on IP address translation, refer to
The IP Network Address Translator (NAT)
RFC 1631,
All contents copyright (c) 2005 ZyXEL Communications Corporation.
P-2608HWL Series Support Notes
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註解 [user1]: Is this still true?
What about 100/1000 Ethernet?
inside
network
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