1.8.3. 路​​​​​​​由​​​​​​​法​​​​​​​則​​​​​​​

圖形 1.22, “LVS Implemented with NAT Routing”, illustrates LVS using NAT routing to move requests between the Internet and a private network.

在​​​​​​​這​​​​​​​個​​​​​​​例​​​​​​​子​​​​​​​裡​​​​​​​，啟​​​​​​​用​​​​​​​中​​​​​​​的​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​有​​​​​​​兩​​​​​​​張​​​​​​​網​​​​​​​路​​​​​​​卡​​​​​​​。​​​​​​​連​​​​​​​上​​​​​​​網​​​​​​​際​​​​​​​網​​​​​​​路​​​​​​​的​​​​​​​網​​​​​​​路​​​​​​​卡​​​​​​​有​​​​​​​位​​​​​​​於​​​​​​​ eth0 上​​​​​​​的​​​​​​​實​​​​​​​際​​​​​​​的​​​​​​​ IP 位​​​​​​​址​​​​​​​，同​​​​​​​時​​​​​​​有​​​​​​​浮​​​​​​​動​​​​​​​ IP 位​​​​​​​址​​​​​​​，連​​​​​​​到​​​​​​​ eth0:1 上​​​​​​​。​​​​​​​私​​​​​​​有​​​​​​​網​​​​​​​路​​​​​​​的​​​​​​​網​​​​​​​路​​​​​​​卡​​​​​​​在​​​​​​​ eth1 上​​​​​​​有​​​​​​​實​​​​​​​際​​​​​​​的​​​​​​​ IP 位​​​​​​​址​​​​​​​，也​​​​​​​有​​​​​​​浮​​​​​​​動​​​​​​​的​​​​​​​ IP 位​​​​​​​址​​​​​​​連​​​​​​​到​​​​​​​ eth1:1 上​​​​​​​。​​​​​​​在​​​​​​​備​​​​​​​援​​​​​​​情​​​​​​​況​​​​​​​發​​​​​​​生​​​​​​​時​​​​​​​，網​​​​​​​際​​​​​​​網​​​​​​​路​​​​​​​與​​​​​​​私​​​​​​​有​​​​​​​網​​​​​​​路​​​​​​​的​​​​​​​虛​​​​​​​擬​​​​​​​介​​​​​​​面​​​​​​​會​​​​​​​由​​​​​​​備​​​​​​​用​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​所​​​​​​​接​​​​​​​手​​​​​​​。​​​​​​​所​​​​​​​以​​​​​​​私​​​​​​​有​​​​​​​網​​​​​​​路​​​​​​​上​​​​​​​的​​​​​​​實​​​​​​​體​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​會​​​​​​​使​​​​​​​用​​​​​​​ NAT 路​​​​​​​由​​​​​​​器​​​​​​​的​​​​​​​浮​​​​​​​動​​​​​​​ IP 做​​​​​​​為​​​​​​​預​​​​​​​設​​​​​​​路​​​​​​​徑​​​​​​​，與​​​​​​​啟​​​​​​​用​​​​​​​中​​​​​​​的​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​溝​​​​​​​通​​​​​​​，這​​​​​​​樣​​​​​​​實​​​​​​​體​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​回​​​​​​​應​​​​​​​網​​​​​​​際​​​​​​​網​​​​​​​路​​​​​​​上​​​​​​​來​​​​​​​的​​​​​​​需​​​​​​​求​​​​​​​，就​​​​​​​不​​​​​​​會​​​​​​​有​​​​​​​問​​​​​​​題​​​​​​​。​​​​​​​

In the example, the LVS router's public LVS floating IP address and private NAT floating IP address are aliased to two physical NICs. While it is possible to associate each floating IP address to its physical device on the LVS router nodes, having more than two NICs is not a requirement.

藉​​​​​​​由​​​​​​​這​​​​​​​種​​​​​​​拓​​​​​​​樸​​​​​​​，啟​​​​​​​用​​​​​​​中​​​​​​​的​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​會​​​​​​​收​​​​​​​到​​​​​​​需​​​​​​​求​​​​​​​，並​​​​​​​導​​​​​​​向​​​​​​​到​​​​​​​正​​​​​​​確​​​​​​​的​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​上​​​​​​​。​​​​​​​實​​​​​​​體​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​會​​​​​​​處​​​​​​​理​​​​​​​這​​​​​​​些​​​​​​​需​​​​​​​求​​​​​​​，然​​​​​​​後​​​​​​​傳​​​​​​​回​​​​​​​給​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​。​​​​​​​LVS 路​​​​​​​由​​​​​​​器​​​​​​​會​​​​​​​使​​​​​​​用​​​​​​​網​​​​​​​路​​​​​​​位​​​​​​​址​​​​​​​轉​​​​​​​譯​​​​​​​，把​​​​​​​封​​​​​​​包​​​​​​​裡​​​​​​​面​​​​​​​實​​​​​​​體​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​的​​​​​​​位​​​​​​​址​​​​​​​替​​​​​​​代​​​​​​​成​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​的​​​​​​​公​​​​​​​開​​​​​​​ VIP 位​​​​​​​址​​​​​​​。​​​​​​​這​​​​​​​個​​​​​​​過​​​​​​​程​​​​​​​稱​​​​​​​為​​​​​​​ IP masquerading（IP 偽​​​​​​​冒​​​​​​​），因​​​​​​​為​​​​​​​實​​​​​​​體​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​的​​​​​​​位​​​​​​​址​​​​​​​被​​​​​​​隱​​​​​​​藏​​​​​​​起​​​​​​​來​​​​​​​，用​​​​​​​戶​​​​​​​端​​​​​​​是​​​​​​​看​​​​​​​不​​​​​​​見​​​​​​​的​​​​​​​。​​​​​​​

使​​​​​​​用​​​​​​​ NAT 路​​​​​​​由​​​​​​​時​​​​​​​，實​​​​​​​體​​​​​​​伺​​​​​​​服​​​​​​​器​​​​​​​可​​​​​​​以​​​​​​​是​​​​​​​執​​​​​​​行​​​​​​​多​​​​​​​種​​​​​​​作​​​​​​​業​​​​​​​系​​​​​​​統​​​​​​​的​​​​​​​任​​​​​​​何​​​​​​​電​​​​​​​腦​​​​​​​。​​​​​​​NAT 路​​​​​​​由​​​​​​​的​​​​​​​主​​​​​​​要​​​​​​​缺​​​​​​​點​​​​​​​是​​​​​​​ LVS 路​​​​​​​由​​​​​​​器​​​​​​​可​​​​​​​能​​​​​​​會​​​​​​​成​​​​​​​為​​​​​​​大​​​​​​​型​​​​​​​建​​​​​​​置​​​​​​​環​​​​​​​境​​​​​​​中​​​​​​​的​​​​​​​瓶​​​​​​​頸​​​​​​​，因​​​​​​​為​​​​​​​它​​​​​​​必​​​​​​​須​​​​​​​處​​​​​​​理​​​​​​​進​​​​​​​、​​​​​​​出​​​​​​​的​​​​​​​需​​​​​​​求​​​​​​​。​​​​​​​