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RIP and SAP are the routing and service advertising protocols traditionally used by NetWare systems to exchange route and service information on an IPX network. RIP is currently the most common routing protocol used on IPX networks.
RIP and SAP perform well in small networks that have simple architectures and few routers. These protocols, however, begin to reveal their limitations in the large, complex internetworks that are becoming increasingly common throughout the installed base of NetWare systems.
By default, RIP and SAP packets are broadcast every 60 seconds, even if no change has occurred anywhere in a route or service. Depending on the size and speed of the network, these periodic broadcasts can consume a significant amount of bandwidth and burden NetWare nodes, especially over WAN links.
Novell Internet Access Server 4.1 provides a configurable parameter, Periodic Update Interval , that enables you to control how often a router broadcasts its route and service updates. This, along with other configurable parameters, such as Aging Interval Multiplier, Pace Override, and Packet Size Override, enables you to fine-tune the operation of RIP and SAP on your router. However, the default values for these parameters are sufficient for most IPX networks and should be changed only on the advice of your technical support representative. A misconfiguration can cause the router to lose routes and services or even generate more traffic than usual.
When configuring RIP on an interface, you can set the RIP State parameter to one of three states: Auto, On, or Off. Auto, the default state, enables the router to accept incoming RIP packets and rebroadcast their routes only if RIP-broadcasting devices, such as NetWare 2 servers, are operating on the attached network. If those devices are removed from the attached network, the Auto -state interface responds by automatically disabling RIP and enabling NLSP. On enables the router to exchange RIP packets freely with other RIP routers on the network. Off disables RIP routing on the interface but does not prevent the router from responding to incoming requests for RIP routes from local NetWare workstations.
Similarly, you configure SAP on an interface with the SAP State parameter, which can also assume one of three states: Auto , On , and Off . Auto , the default state, enables the router to accept incoming SAP packets and rebroadcast their services only if SAP-broadcasting devices, such as NetWare 2 servers, are operating on the attached network. If those devices are removed from the attached network, the Auto -state interface responds by automatically disabling SAP and enabling NLSP. On enables the router to exchange SAP packets freely with other routers on the network. Off disables SAP advertising on the interface but does not prevent the router from responding to incoming requests for services from local NetWare workstations. Additionally, the Off state still allows the router to import locally advertised services.
NOTE: If you want to filter routes or services between routers, use RIP and SAP. NLSP routers cannot filter routes or services.
You should avoid running RIP and SAP over WAN connections because of the cost they incur from periodic transmissions.
This topic contains the following sections:
To configure RIP, complete the following steps:
Load NIASCFG, then select the following parameter path:
Select Configure NIAS > Protocols and Routing > Protocols > IPX
Select Routing Protocol , then select RIP/SAP Only .
Select RIP/SAP Only only if your network has no NLSP routers.
Press Esc to return to the Internetworking Configuration menu, then select the following path:
Select Bindings > a network interface > Expert Bind Options > RIP Bind Options
Select RIP State .
If you want to run RIP over the interface, select On.
This state is necessary for some third-party products that require RIP to operate.
If you do not want to run RIP over the interface, select Off.
This state disables backward compatibility with older routers and servers that use and depend on RIP.
If non-NLSP devices, such as NetWare 2 servers, are operating on the attached network and you want the router to accept and broadcast RIP packets received from these devices, select Auto.
Auto is the default state.
If you want to customize RIP operation further, configure one or more of the following parameters:
IMPORTANT: Because the default settings for these parameters are suitable for most RIP-based IPX networks, you should change them only for a specific purpose. Misconfiguring these parameters can increase routing traffic or cause loss of connectivity on your network.
Each router on the network segment to which this router is attached must use the same value for the Periodic Update Interval .
Increasing the Aging Interval Multiplier slows the rate at which the router ages the routes in its Routing Information Table. This is necessary to keep routes that might otherwise be aged out of the routing table because of dropped RIP updates. The default value for the Aging Interval Multiplier is 4. For example, if RIP packets are sent every 60 seconds (Periodic Update Interval equals 2), the router keeps the route information for 240 (60 x 4) seconds without refreshing it. Each router on the network segment to which this router is attached must use the same value for the Aging Interval Multiplier .
The default value for this parameter is 0, which means do not override the current pace.
Each router on the network segment must use the same RIP packet size.
Press Esc and save your changes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System .
If you want to configure other parameters, do so now, then reinitialize the system when you are finished.
To configure SAP, complete the following steps:
Load NIASCFG, then select the following parameter path:
Select Configure NIAS > Protocols and Routing > Protocols > IPX
Select Routing Protocol , then select RIP/SAP Only .
Press Esc to return to the Internetworking Configuration menu, then select the following path:
Select Bindings > a network interface > Expert Bind Options > SAP Bind Options
Select SAP State .
If you want to run SAP over the interface, select On.
This state is necessary for some third-party products that rely on SAP to advertise their services. Setting SAP State to On also enables RIP routing on the interface.
If you do not want to run SAP over the interface, select Off.
This state disables backward compatibility with older routers and servers that use and depend on SAP. The router responds to incoming SAP requests, such as Get Nearest Server, even if SAP is disabled on this interface.
If non-NLSP devices, such as NetWare 2 servers, are operating on the attached network and you want the router to accept and broadcast SAP packets received from these devices, select Auto.
Auto is the default state.
If you want to customize SAP operation further, configure one or more of the following parameters:
IMPORTANT: Because the default settings for these parameters are suitable for most RIP-based IPX networks, you should change them only for a specific purpose. Misconfiguring these parameters can increase routing traffic or cause loss of connectivity on your network.
No Override ---Do not override the global setting for the router. This is the default state.
Ignore ---Ignore Get Nearest Server requests received through this interface.
Accept ---Accept Get Nearest Server requests received through this interface.
Each router on the network segment to which this router is attached must use the same value for the Periodic Update Interval .
The default value for the Aging Interval Multiplier is 4. For example, if SAP packets are sent every 60 seconds (Periodic Update Interval equals 2), the router keeps the service information for 240 (60 x 4) seconds without refreshing it. Each router on the network segment to which this router is attached must use the same value for the Aging Interval Multiplier .
The default value for this parameter is 0, which means do not override the current pace.
Each router on the network segment must use the same SAP packet size.
Press Esc and save your changes.
Press Esc to return to the Internetworking Configuration menu.
If you want these changes to take effect immediately, select Reinitialize System .
If you want to configure other parameters, do so now, then reinitialize the system when you are finished.
Novell Internet Access Server 4.1 routing software includes a SET command that enables an IPX router to accept and advertise a service from another network, even if the network number associated with the service is not listed in the router's Routing Information Table.
The syntax of this command is as follows:
SET REQUIRED NETWORK FOR SERVICES=ON|OFF
To understand how this command works, consider Figure 12, which shows two directly connected IPX routers, one serving a large backbone network, the other serving a NetWare LAN.
Figure 12
IPX Router Accepting and Advertising Services from a Network Not Listed in the Routing Information Table
Suppose a NetWare server somewhere within the backbone network advertises its file services, which the backbone router receives as a SAP packet (Service Type=0x0004 and Network Number=0x01234567, for example). When the LAN router receives the SAP packet from the backbone router, it checks its Routing Information Table for the network number 0x01234567.
If the LAN router finds the network number, it adds the associated service information to its services table and advertises the service to the LAN during the next SAP broadcast. If the LAN router does not find the network number, it discards the packet. This function occurs if the following command has been entered at the LAN router:
SET REQUIRED NETWORK FOR SERVICES=ON
This function is disabled by default. However, if this function has been enabled by the preceding command, it can be disabled by entering the following command:
SET REQUIRED NETWORK FOR SERVICES=OFF
If the previous command has been entered, the LAN router will not discard the packet if it does not find the network number in its Routing Information Table. If the router does not find the network number, it first checks for the nearest NLSP level 2 router and then for the RIP default route (0xFFFFFFFE) or an aggregated route. If the LAN router finds one of these, it adds the associated service information to its services table. If the LAN router does not find any one of these, it then discards the SAP packet.
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