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Associated with each WAN call destination is the call type, which characterizes the behavior of the call after it is established. Calls can be permanent or on-demand.
For more information about call types, refer to:
A permanent call is a connection that remains active between the local router and the remote router identified by the call destination. A permanent call can be established automatically from configured protocol-to-board bindings, or manually from CALLMGR. The call remains active until IPX is unbound from the interface, or until the connection is disconnected manually from CALLMGR. If a permanent call fails, IPXRTR tries to reestablish the connection.
IPX routing and service information crosses permanent calls as required by the operative routing/service protocol, which can be RIP/SAP or NLSP. If you do not want routing and service traffic to cross a permanent-call link, the routing software enables you to configure static routes and services on each router. This is typically how IPX routers are made aware of remote routes and services over links that use on-demand calls.
For information about static routes and services, refer to Static Routes and Services.
For more information about permanent calls, refer to "Understanding" in the routing documentation for NetWare/Link PPP.
An on-demand call is a dedicated, point-to-point connection between two routers that becomes active only when one router must send user data to the other. Because the on-demand call relies on configured static routes and services, no routing or service information crosses the link while the call is active.
With an on-demand call, the link remains inactive until user data needs to cross it. Workstations needing to reach remote destinations send packets to their local IPX router advertising the routes, assuming the packets can reach their destination. The local router stores the packets and tries to establish a connection to the remote router. After the local router completes the call and negotiates on-demand service, it forwards the stored packets to the remote router, which then forwards them to their destination.
NOTE: To avoid activating potentially expensive connections, IPX routers do not forward type 20 (NetBIOS) packets over on-demand calls.
For more information about on-demand calls, refer to "Understanding" in the routing documentation for NetWare/Link PPP.
NetWare routing also enables you to configure a routed on-demand call. Unlike the standard on-demand call, which relies on statically configured routes and services, a routed on-demand call runs a routing protocol while the link is active. When the link goes down, the routes and services made known by the routing protocol become unavailable.
If no data crosses the link after some period of time, a Data-Link layer timer triggers the termination of an on-demand call. However, the routing protocol running over a routed on-demand call resets this timer each time it transmits a packet. This keeps the link continuously active. To solve this problem, the routing software uses a similar timer that operates at the Network layer. This timer is reset only when data packets---not protocol packets---cross the link. In this way, the routing updates do not keep the link active when no data is being transmitted.
Routed on-demand calls are well-suited for large corporate networks that have many branch offices. In this type of internetwork, most of the traffic is unidirectional: from the branch office to the corporate network. Configuring each branch office with a single (default) route to the corporate network is sufficient. When a branch office router establishes a link to the router serving the corporate network, the routing protocol floods the branch office routes into the corporate network. This is necessary so that responses to branch office service requests know how to reach their destination in the branch office network. As long as the branch office forwards information to the corporate network, the link remains active. If the link is idle for some predetermined period of time, it goes down.
You configure a routed on-demand call the same way you configure a standard on-demand call with one exception: you must configure a routing protocol to operate over the link.
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