Configuring Static Routes 129The solution in this scenario is to enter a static route on the Webcache touse a LAN-side router for all requests destined for the LAN-side server.When the Webcache processes the cache miss, instead of passing thepacket to the default router, it sends it to the LAN-side router which hasdirect connectivity to the LAN-side server. Everything now functions asexpected.Advantages of StaticRoutesStatic routing has the following advantages over dynamic routing: Predictability — The path a packet takes between two destinations isalways known precisely because you compute the route that thepacket takes in advance. With dynamic routing, the path takendepends on which devices and links are functioning, and how therouters interpret the updates from other routers. Less Overhead — Static routing does not impose any overhead onthe routers or the network links because no dynamic routing protocolis required. This overhead could amount to a significant portion ofnetwork bandwidth on a low-speed dial-up link. In a network with200 network segments, every 30 seconds, as required by the RIPspecification, all the routers send an update containing reachabilityinformation for all 200 of these segments. With each route taking 16octets of space, plus a small amount of overhead, the minimum sizefor an update in this network is over three kilobytes. Each router musttherefore send a 3KB update on each of its interfaces every 30seconds. For a large network, the bandwidth devoted to routingupdates can quickly add up.In addition to Static Routes, the Webcache also listens to and respectsICMP redirect messages directed to it from routers on your network.Configuring StaticRoutesTo configure static routes using the Web interface:1 Log in to the Web interface.2 Click Device on the Toolbar.3 Select System > Protocol > Static Routes. The Static Routes screen isdisplayed.4 Enter the IP address of the network that you are creating a static route forin the IP Address field.dua1611-5aaa04.book Page 129 Friday, November 29, 2002 8:56 PM
