2.2.3.3 Choose a Routing Service

In order for packets to be delivered to devices on remote networks, at least one device on the local network must be configured to forward packets from the local network segment to the remote network segment(s). These devices are called routers.

There are a variety of different mechanisms used for routing packets in an IP network. The most simplistic routing mechanism is called "static routing," whereby an end-node (such as a desktop PC) is configured to simply forward any packet destined for a remote network to a pre- determined router. It is up to the router to deliver the packet from that point on.

Beyond this simple blind-forwarding approach, there are also several routing "protocols" that actively monitor the state of the network and make dynamic routing decisions based on the availability of various routers on the networks. The most common routing protocol is RIP (Router Information Protocol), which is very similar to the RIP protocol used on IPX networks. RIP routers publish a list of the networks that they are connected to every sixty seconds. Other RIP-aware devices on the network then read these advertisements and update their local routing tables accordingly. This allows a device to choose a specific router to use for delivery based on the information being published.

RIP works well in small networks, but does not work well in large or complex networks, as the routing tables can quickly become very large, slowing network performance tremendously. Another router protocol commonly found in larger organizations is OSPF (Open Shortest Path First). OSPF does not use frequent broadcasts and explicit maps to constantly update the network map, but instead uses infrequent "alerts" to notify devices of changes in the map. Also, the map itself allows for aggregating routes together, making the maps smaller, thereby improving performance.

You may need to discuss this subject with other system administrators, consultants, or service providers in order to determine the appropriate routing service, or to determine the IP address of the local router.

There are many other routing protocols, although static, RIP and OSPF are the most common. The routing service you will use for the NetWare server will be determined by a variety of factors:

• If you already have TCP/IP installed on other systems on the same network that this server is on, then look at the routing service in use on those other devices. If they are using static routing, then you should use that service as well, and you should use the same default route that those other systems use. Check the "Static Routing" checkbox, and also write the default route in the "Default Route" field in the configuration worksheet. If the other devices on your network are using RIP or OSPF, then you should check one of those checkboxes in the configuration worksheet.
  
  
• If you do not have TCP/IP installed on other systems on the same network but do have TCP/IP installed on other networks within your organization, then you should probably use the same routing protocol in use on those other networks. If those other systems are using static routing, then you will need to determine the IP address of a router on your local network that is capable of forwarding packets to those other networks. Check the "Static Routing" checkbox, and write down the IP address of the local router in the "Default Route" field in the configuration worksheet. If the other devices are using RIP or OSPF, then you should check one of those checkboxes in the configuration worksheet.
  
  
• If you do not have TCP/IP installed on any systems within your organization, but have (or will soon have) a routed connection to the Internet, then you should request the type of routing service in use from your Internet Service Provider. If the local router will be using static routing, then check the "Static Routing" checkbox, and write the IP address of the local router in the "Default Route" field in the configuration worksheet. If the local router will be using RIP or OSPF, then check one of those checkboxes in the worksheet shown in Figure 2.1.
  
  
• If you do not have TCP/IP installed on any systems within your organization, or you do not plan to have a routed connection to the Internet, then you do not need to specify a routing service.
  

For more information on IP routing, refer to section B.4 IP Routing.

STEP: To continue to the next step in the configuration process, go to section 2.2.4 Determine the Naming Service Information.

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