ZyXEL ISG50-PSTN User Guide - Page 282

Chapter 13 Trunks • You can define multiple trunks for the same physical interfaces. Link Sticking You can have the ISG50 send each local computer's traffic that is going to the same destination through a single WAN interface for a specified period of time. This is useful when a server requires authentication. For example, the ISG50 sends a user's traffic through one WAN IP address when he logs into a server B. If the user's subsequent sessions came from a different WAN IP address, the server would deny them. Here is an example. Figure 188 Link Sticking 1 wan1 ISG 2 wan2 LAN 3 B A 1 LAN user A logs into server B on the Internet. The ISG50 uses wan1 to send the request to server B. 2 The ISG50 is using active/active load balancing. So when LAN user A tries to access something on the server, the request goes out through wan2. 3 The server finds that the request comes from wan2's IP address instead of wan1's IP address and rejects the request. If link sticking had been configured, the ISG50 would have still used wan1 to send LAN user A's request to the server and server would have given the user A access. Load Balancing Algorithms The following sections describe the load balancing algorithms the ISG50 can use to decide which interface the traffic (from the LAN) should use for a session2. The available bandwidth you configure on the ISG50 refers to the actual bandwidth provided by the ISP and the measured bandwidth refers to the bandwidth an interface is currently using. 2. In the load balancing section, a session may refer to normal connection-oriented, UDP or SNMP2 traffic. 282 ISG50 User's Guide