城域网广域网设计和接入技术.ppt

* * Purpose: This figure is a transition that highlights the NAT functions that are presented in the next few figures. Emphasize: The next few figures discuss the following NAT functions: Translating inside global addresses Overloading inside global addresses Handling overlapping networks Transmission Control Protocol (TCP) load distribution Transition: The next figure describes translating inside global addresses. * Purpose: This figure is a graphical illustration of the chapter objectives. * Purpose: This figure is a transition into the NAT overview section. It also highlights some important NAT terms. Emphasize: Highlight the different sending addresses on the packet before it enters the router and after it leaves the router. Compare those addresses to those listed on the NAT table. Describe each term as it relates to the figure. Note: The letters on the figure correspond to the descriptions in the text. Descriptions for outside local IP address and extended translation entry are not represented graphically. Easy IP is a related feature to NAT available on Cisco routers. Configuring Easy IP is not taught in this course. The Easy IP (Phase 1) feature combines NAT and Point-to-point (PPP)/Internet Protocol Control Protocol (IPCP). This feature enables a Cisco router to automatically negotiate its own registered WAN interface IP address from a central server and enable all remote hosts to access the global Internet using this single registered IP address. Because Easy IP (Phase 1) uses existing port-level multiplexed NAT functionality within the Cisco IOS software, IP addresses on the remote LAN are invisible to the Internet. Reference: For a complete description of the Easy IP configuration commands, refer to the “Easy IP Commands” chapter in the Dial Solutions Command Reference. * Purpose: This figure explains how overloading inside global addresses works. Emphasize: Overloading inside global address translation is Port Address Translation (PAT). How to configur