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NetWare servers have traditionally used the Routing Information Protocol (RIP) to route IPX packets, and the Service Advertising Protocol (SAP) to exchange service information with other NetWare servers. In addition to providing the same functionality for network devices that rely on RIP and SAP (NetWare 2 servers, for example), NLSP provides link state routing for IPX internetworks.
NLSP is derived from IS-IS (Intermediate System-to-Intermediate System), the link state routing protocol developed by the International Standards Organization (ISO). Like IS-IS, NLSP exchanges routing information between routers and makes routing decisions based on that information. For workstation-to-router communication, NLSP routers continue to use RIP and SAP.
NLSP routers exchange information such as connectivity states, path costs, throughput, maximum packet size (MTU size), and networks learned through RIP (external network numbers). In networks with RIP/SAP devices, the routers keep track of services and external (RIP-based) routes. This information is carried in a Link State Packet (LSP). By exchanging this information with its peer routers, each NLSP router builds and maintains a logical map of the entire internetwork.
Unlike RIP and SAP, which periodically broadcast routing and service information, NLSP transmits routing information only when a change occurs in a route or service, or every two hours---whichever occurs first.
Migrating an IPX internetwork to NLSP involves only the NetWare servers and routers; you do not need to install additional software on the NetWare workstations. NLSP is compatible with all NetWare workstations and RIP/SAP routers, and with other network devices---such as print servers---that use SAP to advertise their services.
Although NLSP is a routing protocol specifically for IPX, it is not limited to pure IPX LANs. NLSP operates seamlessly within multiprotocol LAN and WAN environments, such as TCP/IP, AppleTalk*, frame relay, and X.25, to name a few.
The IPXRTR NetWare Loadable ModuleTM (NLMTM) file is the IPX protocol stack for the NetWare operating system. IPXRTR provides combined NLSP routing and full RIP/SAP functionality for network-level operations.
IPXRTR allows you to enable or disable RIP, SAP, and NLSP selectively on network interfaces within the same server or router. For example, you can use RIP and SAP exclusively on one interface and NLSP on another. Additionally, an interface can use NLSP as the active routing protocol but still accept and process RIP and SAP broadcasts from network devices that use RIP and SAP.
IPXRTR also allows you to bind IPX to two or more network interface boards connected to the same LAN. This enables NetWare workstations on that LAN to use either interface when accessing the server---a feature called load balancing or load sharing.
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