ZyXEL ZyWALL USG 2000 User Guide - Page 359

Chapter 15 Policy and Static Routes Table 84 Configuration > Network > Routing > Static Route > Add (continued) LABEL DESCRIPTION Gateway IP Select the radio button and enter the IP address of the next-hop gateway. The gateway is a router or switch on the same segment as your ZyWALL's interface(s). The gateway helps forward packets to their destinations. Interface Select the radio button and a predefined interface through which the traffic is sent. Metric Metric represents the "cost" of transmission for routing purposes. IP routing uses hop count as the measurement of cost, with a minimum of 1 for directly connected networks. Enter a number that approximates the cost for this link. The number need not be precise, but it must be 0~127. In practice, 2 or 3 is usually a good number. OK Click OK to save your changes back to the ZyWALL. Cancel Click Cancel to exit this screen without saving. 15.4 Policy Routing Technical Reference Here is more detailed information about some of the features you can configure in policy routing. NAT and SNAT NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address in a packet in one network to a different IP address in another network. Use SNAT (Source NAT) to change the source IP address in one network to a different IP address in another network. Assured Forwarding (AF) PHB for DiffServ Assured Forwarding (AF) behavior is defined in RFC 2597. The AF behavior group defines four AF classes. Inside each class, packets are given a high, medium or low drop precedence. The drop precedence determines the probability that routers in the network will drop packets when congestion occurs. If congestion occurs between classes, the traffic in the higher class (smaller numbered class) is generally given priority. Combining the classes and drop precedence produces the ZyWALL USG 2000 User's Guide 359