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This topic explains how the NLSP routing protocol can benefit your IPX internetwork.
This topic includes the following sections:
This section presents several reasons supporting the use of NLSP on an IPX internetwork.
This section answers questions that NetWare® administrators often ask about NLSP.
This section summarizes the principal benefits of running NLSP on your internetwork.
Each RIP router broadcasts its entire routing table and service database every 60 seconds, even if none of the information has changed since the previous broadcast. This generates a significant amount of traffic on the internetwork.
By contrast, NLSP transmits information only when a change occurs in a route or service, or every two hours---whichever occurs first. Although this information is broadcast by default, it can be multicast if the network interface driver supports multicast transmission.
When a router or a link comes up or goes down, or when a service becomes available or inaccessible, it takes time for that information to become known to all routers throughout the internetwork. Convergence is the process by which a routing protocol learns of a topology or service change and makes that change known to each of the active routers on the internetwork. A network is said to have converged when all routers once again share the same view of the network.
As a link state routing protocol, NLSP converges faster than RIP, the traditional distance vector routing protocol for IPX. Fast convergence is advantageous for the following reasons:
While a network is converging, there is a brief period during which the routers are busy rebuilding their routing databases. In-transit packets are often lost during this process.
With NLSP, you can build and operate larger IPX internetworks than are possible with RIP.
Although packets relayed by RIP routers can travel no more than 15 hops between their source and destination, packets relayed by NLSP can travel up to 127 hops.
Periodic SAP broadcasts consume substantial bandwidth and can even saturate low-speed WAN connections.
NLSP uses a highly efficient and reliable delivery mechanism for transmitting and updating service information across a WAN connection. Because no SAP (or RIP) traffic travels across the connection, NLSP improves performance significantly on WANs. Also, because NLSP ensures reliable delivery, it eliminates the need for retransmissions that waste bandwidth.
NLSP makes efficient use of network resources by automatically distributing forwarded traffic across network interfaces. That is, given two or more equal-cost routes between two network nodes, NLSP distributes the traffic evenly among them. If you have NetWare 4.1 or Novell Internet Access Server 4.x software, you can use the Novell Internet Access Server Configuration utility (NIASCFG) to specify up to eight equal-cost routes or even configure a router to use a single route.
For added efficiency over WAN connections, NLSP compresses the IPX packet headers to reduce the size of data packets. NLSP also reduces the size of the service information it carries. Together, these features further reduce overhead traffic and make more network bandwidth available for actual data. The increase in data transfer speed is especially noticeable across WAN connections.
Any network management application that uses Simple Network Management Protocol (SNMP)---such as Novell's ManageWise® software---can monitor an NLSP router or a RIP router implemented to the Management Information Base (MIB) specification. You can then use these applications to derive a topology map of your entire IPX internetwork from a single NLSP router.
Such far-reaching management capability enables you to detect problems such as duplicate network numbers, inactive routers or links, and even failed interface boards anywhere on your internetwork.
NLSP routers know the cost of every link and use this information to choose the most efficient route for each outgoing packet.
NIASCFG enables you to change the cost of a link. For example, you can increase the cost of a particular link so that NLSP routes traffic through a preferred, less-expensive link.
Because NLSP is fully compatible with IPX RIP and SAP, you can use NLSP and RIP routers together in the same internetwork. NLSP routers also interoperate with devices and applications that use or depend on RIP and SAP. NLSP encapsulates and propagates the routing and service information it receives from RIP/SAP devices and networks.
You can also migrate NetWare LANs from RIP to NLSP as needed; you do not need to migrate your entire internetwork at the same time.
The following sections answer some commonly asked questions about NLSP.
Yes. Like RIP, SAP propagates service information every 60 seconds. NLSP also carries service information, but broadcasts it only when a change occurs in a service or route, or every two hours---whichever occurs first. By these figures, NLSP reduces service advertising overhead to 1/120 of that generated by SAP. In a typical internetwork running NLSP, you can expect a 90 to 99 percent reduction in service advertising overhead.
However, the best long-term solution for reducing SAP overhead is to use NetWare 4 software and enable your applications to use Novell Directory ServicesTM (NDSTM) software.
Each large internetwork is different in its complexity and the network events it must process. Some events are processed more quickly by distance vector protocols; others are processed more quickly by link state protocols.
Link state protocols dispense with many of the time-consuming tasks associated with traditional distance vector protocols. Also, older implementations of distance vector protocols are often inefficient.
Novell has tested NLSP in very large networks, and has verified that the algorithms perform well and use a nominal amount of CPU.
Typically they do, but not in every network. In addition to the 290 KB that IPXRTR requires, NLSP uses about 600 KB in a large internetwork of 3,000 network numbers and 1,600 services.
Yes. Because NLSP is fully RIP/SAP-compliant, it interoperates with third-party routers that support IPX RIP/SAP. NLSP cannot, however, reduce the amount of RIP/SAP traffic where those routers are located.
For third-party routers that support Internet Protocol (IP) routing, you can use the IPRELAY driver to tunnel through the third-party routers. IPRELAY is available with the NetWare MultiProtocol RouterTM 3.x software or the Novell Internet Access Server 4.x software. For more information, refer to Tunneling Through Third-Party IP Routers.
Many third-party router manufacturers plan to support NLSP. Contact your router manufacturer for details.
There are still advantages to running NLSP software on your internetwork, even if some third-party routers on the internetwork do not yet support NLSP:
Yes. NLSP automatically detects the presence of NetWare 2 software on an internetwork. However, wherever you have a mix of NetWare 2 and NetWare 3TM servers, you run NLSP, RIP, and SAP.
NLSP allows for up to 230 systems---routers and servers combined---on a single Ethernet LAN segment. This number is higher for token ring and FDDI networks, depending on the maximum packet size you configure on each server on the LAN.
Yes. NLSP can run on the same network---or even the same router---with Open Shortest Path First (OSPF) and IS-IS routing protocols. Because NLSP information is carried within IPX packets, it does not interfere with other routing protocols running on the same network.
Yes. NLSP, IPX RIP, and SAP use MIB variables in SNMP format that are fully compatible with the following network management products:
Some of these products have already integrated the NLSP, IPX RIP, and SAP MIB variables. IPX Upgrade for NetWare Servers provides these MIB variables in ASN.1 format so that you can use your MIB compiler to convert them into a format that your network management software can use.
The primary difference is the rate at which NLSP routers send keep-alive messages---in the form of Hello packets---to their peers. If a system is not forwarding packets (that is, not operating as a router), there is little need to send Hello packets frequently. On an NLSP router, however, you should consider increasing the Hello Interval frequency. This enables other NLSP routers on the internetwork to detect failed routers more quickly so that an alternate route can be chosen.
Generally, wherever you want. However, if you have a WAN mesh internetwork, that is typically the best place to start.
If you have a large internetwork, first decide how you intend to partition it into routing areas, then migrate the routers at the area boundaries. You should also migrate one LAN at a time. Guidelines for partitioning your internetwork are presented in Defining Routing Areas in an Internetwork.
Even if your internetwork uses third-party routers that support RIP/SAP but not NLSP, you can still migrate your NetWare servers to NLSP. In this case, the servers and third-party routers can continue to exchange routing information using RIP/SAP. When you later migrate your dedicated routers and integrated server-routers to NLSP, your NetWare servers automatically use NLSP instead of RIP/SAP to exchange routing information with the NLSP routers.
As the percentage of NLSP routers on your internetwork increases, the bandwidth use and convergence time improves throughout your internetwork.
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