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As described earlier, NetWare Link/PPP on-demand connections are initiated at the request of network protocols when data is present that must be routed to a remote LAN, and they are terminated when the NetWare Link/PPP WAN connection is determined to be idle. Standard network protocols generally expect each WAN circuit to provide permanent connections to all remote systems. The reason is that the network protocols rely on periodic communication with remote systems to dynamically exchange routing updates and, in the case of IPX, service advertising updates. These periodic exchanges identify the network routes and services that are known on each remote LAN accessed over the WAN connections.
Depending on the size of each remote LAN and the speed of the WAN connection, periodic maintenance exchanges can result in a constant stream of data across the NetWare Link/PPP connection, which prevents on-demand connections from terminating using idle-link detection. However, without the maintenance exchanges, Network-layer protocols do not have the information required to route data to the proper remote systems, and on-demand connections are never established because the local network protocols are not aware of the accessible WAN routes and services.
To provide the required route and service information without tying up the on-demand connection, the Novell Internet Access Server 4.1 routing software offers two alternatives:
Static route and service databases ---Each database is network protocol-specific and contains a manually configured subset of the route and service information. Manual configuration eliminates the need for periodic maintenance updates because the required route and service information is already available in the static databases of each system. When the Novell Internet Access Server 4.1 routing software receives a request for a manually configured static route or service, it supplies the routes and services information to other network nodes and makes a WAN call to the configured node.
A single static route is also useful as a default route for IPX or TCP/IP hosts. In this way, the only routing information crossing the link is that required by users to access a specific set of services.
Static routes and services are configured using NIASCFG. In the case of IPX, the Static Routing Configuration utility (STATICON) provides a simplified method to configure static routes and services. STATICON accesses information from the router across the WAN link if the router supports the IPX Management Information Base (MIB) provided with the Novell Internet Access Server 4.1 routing software and Simple Network Management Protocol (SNMP) over IPX. Documentation for the IPX MIB is provided in the IPXMIB.TXT file on the product CD-ROM.
Routed on-demand calls (with IPX and IP protocols) ---A routed on-demand call runs the IPX or IP routing protocol over the link. The timeout for a routed on-demand call is based on the receipt of Network-layer data packets. In this way, the Novell Internet Access Server 4.1 routing software is able to get the benefit of running routing protocols over the on-demand link without the IPX or IP packet traffic keeping the link continuously active. Routed on-demand calls are well-suited for large corporate networks that have many branch offices. For more information on routed on-demand calls, refer to Understanding in the IPX documentation and Understanding in the TCP/IP documentation.
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