tailieunhanh - building a cicso network for windows 2000 phần 2

Để kết nối với Internet, bạn sẽ cần phải có một địa chỉ IP đăng ký cho mạng của bạn. Một số tổ chức, tuy nhiên, yêu cầu địa chỉ nhiều hơn so với họ đã có sẵn trong bộ địa chỉ đã đăng ký. Để có được xung quanh vấn đề này, đề nghị (RFC) 1918 cung cấp địa chỉ đăng ký. | 34 Chapter 1 Developing a Windows 2000 and Cisco Internetwork TE To connect to the Internet you will need to have a registered IP address for your network. Some organizations however require far more addresses than they have available in their registered address set. To get around this issue Request for Comments RFC 1918 provides unregistered addresses. To use them and still connect to the Internet the organization must translate between a registered IP address that is applied to an interface connected to the Internet and the unregistered IP addresses that are applied to the hosts on the internal network. This process is called network address translation NAT . RFC 1918 reserves the following addresses Class Class to Class to RFC 1918 is available at ftp rfc . The remaining addresses from 224 through 239 are reserved for class D or multicasting. From 240 through 255 the addresses are considered class E or experimental. No matter what address a host is assigned it must be unique on the internetwork. IP addressing and routing can be performed without the use of classes. This is called Classless InterDomain Routing CIDR . Each distinct route on the network is not advertised separately. Instead it is aggregated with multiple destinations. One benefit of using CIDR is to reduce the size of the routing tables. Each address must have a way of separating the network s IP address from the host s IP address. This is achieved with a mask. When you subtract the mask from the full address the result separates the two. Each class of addresses has its own default mask. A class A address has the default mask of . As you see the first octet is masked enabling the IP address portion to remain. The default mask for class B is and the default mask for class C is . When a network administrator wants to apply a network address to two different network segments the IP