ccna 200 301 bookshelf with doors

ccna 200 301 bookshelf with doors.The people who created the IP addressing mechanism also created private IP addresses, which are defined in RFC 1918. These addresses can be used in private networks, but cannot be routed over the Internet. This design provides a degree of security for private networks, while saving valuable IP address space.If every host in every network had to use a truly routable IP address, it would have run out of IP addresses 800 years ago. By using private IP addresses, ISPs, businesses, and home users can connect their devices to the Internet using only a few addresses. This economical practice allows them to use private IP addresses on their own internal networks and then connect to the Internet without hassle.5.1 IPv4 Addressing 141To accomplish this, ISPs and enterprises-that is, end users, it doesn't really matter what their organization is-need to use a mechanism called network address translation (NAT) so that the private IP addresses used by their internal networks into an address that can be routed across the Internet. For the end user, there can be many people using the same IP address and connecting to Intemeto This way we save a lot of address space - good for everyone!NAT is covered in detail in my other book: the Cisco Certified Network Associate Study Guide, 7th edition (Sybex,2011)Take a look at the NAT conversion example shown in Figure 5.2 to configure NAT conversion on an enterprise router for an enterprise conversionFigure 5.2 NAT translation for public IP addresses and private IP addresses. The real global IP address must be configured on the interface that connects to the Internet, and the addresses configured on the Engineering and Sales routers are private IP addresses. The following rules are important. Private addresses (RFC1918) cannot be globally routed in the Internet. RFC1918 defines the networks that must be reserved in each class of addresses: 1 network for Class A; 16 networks for Class B; and 256 networks for Class C. These IP address ranges defined in RFC1918 can only be used in internal networks.RFC1918 slows the transition to IPv6. Private addresses must be filtered out on Internet boundary interfaces. Private addresses include still . 0.0.0/8, 172.16.0.0/16, and 192.168.0.0/16.Network address translation needs to be implemented on Internet border devices. The reserved private IP addresses are listed in Table 5.2.Chapter 5 IP Addressing Table 5.2 Reserved IP Address Space