Chapter 3 - Beginning the TCP/IP Planning Process
To begin the TCP/IP planning process, you should:
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Know your topology ![]()
Know the configuration tasks ![]()
Evaluate the complexity of your configuration
A server equipped with a TCP/IP option is part of a network topology, which is a pattern of systems and the physical links that connect them in computer networks.
This section helps you to recognize the facts about your server's network topology that you will need to plan your TCP/IP configuration. Topics discussed in this section include:
Drawing a Network Topology Diagram
Draw a diagram of your network topology, and make it as thorough as possible. The diagram should show the following:
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Your server ![]()
All other servers or PCs equipped with TCP/IP that you know about ![]()
LANs that directly connect your server to other hosts - servers, PCs, foreign hosts, and foreign host gateways ![]()
Servers acting as gateways and foreign host gateways on each LAN, and how they are connected to the rest of the network ![]()
The IP networks and subnetworks in which your server resides ![]()
As many destinations outside your network as possible
If you need more information to draw a topology diagram, consult with other network management personnel. Figure 3-1 shows a sample topology diagram. The figure was drawn from the perspective of Server 1. It is used in most examples in this chapter, as well as throughout Chapter 4, Chapter 5, and Chapter 6, to illustrate how to plan a TCP/IP configuration.
In your topology diagram, identify other servers equipped with TCP/IP, and the specific TCP/IP options on them. Later, you will use the TCP/IP configuration program to associate the IP addresses with the names and serial numbers of the servers. Figure 3-1 identifies the TCP/IP options on Server 1 and Server 2.
Identifying Workstations Equipped with PC/TCP
If your server has the Routing option installed, identify all the PCs equipped with PC/TCP or TCP/IP kernels from Ipswitch, Inc. or other sources that will use your server as a gateway.
PC/TCP is a software package created by FTP Software, Inc. Banyan software works with two versions of this software:
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Ethernet-only version ![]()
VINES Transport version
The Ethernet-only version works only on VINES workstations that have an Ethernet interface. This package bypasses all VINES workstation software and sends pure IP packets across the wire. Workstations with this version of PC/TCP must be physically connected to a server running the VINES Routing option, or to a foreign host gateway.
The VINES Transport version can be installed on any workstation that has a VINES-supported network interface card. This software encapsulates IP packets in a VINES packet, then sends the VINES packet across the network.
Note that workstations running the VINES Transport version of PC/TCP can be located anywhere in a VINES network. They need not share a physical interface with a VINES server that has a TCP/IP option. They do, however, share a logical interface with the server. The VINES interface of the server gateway must be configured through the TCP/IP menus. Using this interface, the server accepts packets from the PCs and routes them to their destinations.
Identify all the network interfaces on your server. Give special consideration to those interfaces that IP supports. If your server has the Routing option installed, you may treat VINES as an interface. In Figure 3-1, Server 1 has three interfaces, all of which IP uses - two Ethernet interfaces and VINES.
When you plan your TCP/IP configuration, you must decide on IP addresses for each interface on your server. Assign an IP address to the VINES interface only if a PC running PC/TCP resides in your server's VINES network, and will use the server as a gateway. Refer to Chapter 4.
Identify IP networks and subnetworks that your server must reach, and their respective numbers, if possible. In many cases, a single IP network is located in a cluster of buildings, such as a college campus, where all hosts are linked by LANs. Typically, each LAN is assigned a subnetwork number, which appears in the IP addresses of all hosts on the same LAN.
You need network numbers to define routes to destinations. Figure 3-1 notes the numbers of the networks connected to Server 1 - 160.134 and 130.133. Refer to Chapter 6 for more information.
If your server has the Routing option installed, identify the IP networks to which your server will route IP packets. If your server has the Server-to-Server option installed, identify the IP networks in which other servers equipped with this option reside.
Identifying your server's VINES network helps you to plan your routing table. For example, Figure 3-1 identifies Server 1's VINES network.
Identifying Gateways and Routes
Identify servers acting as gateways and foreign host gateways, and routes to the destinations through them. When you plan your routing table, you must associate the IP addresses of gateways to specific network interfaces, and destinations.
In Figure 3-1, all gateways for Server 1 are labeled, including those that are not connected directly by LANs to Server 1.
Make sure that you identify each server gateway in your VINES network. For example, Server 1 is the gateway in Server 1's VINES network.
The role that a server gateway performs depends on which option is installed. Using the Server-to-Server option, a server gateway encapsulates a VINES packet inside an IP packet, and routes the IP packet through an IP network. It can also strip the IP header off the packet, then route the VINES packet to its destination within the VINES network.
Using the Routing option, server gateways encapsulate IP packets within VINES packets and route the VINES packets to destinations in the VINES network. If the VINES server that receives the packet also has the Routing option installed, it can strip the VINES header from the packet and route the IP packet to a destination within an IP network. When you plan routing tables for servers with the Routing option installed, you may have to set up routes through server gateways to foreign hosts. Refer to Chapter 6 for more information.
Coordinating with Other Network Personnel
You should now know enough about your topology to begin planning the TCP/IP configuration for your server. You can obtain some configuration information from personnel responsible for other IP hosts and networks. Some configuration information has to come from you.
Knowing the Configuration Tasks
You use the TCP/IP configuration program to perform the following tasks:
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Specify information that IP interfaces require. You also control interfaces and manage address resolution over LANs. (For planning guidelines, see Chapter 4; for instructions, see Chapter 8.) ![]()
Specify foreign host gateways through which you can route IP traffic to a TCP/IP network, subnetwork, or host. (For planning guidelines, see Chapter 5; for instructions, see Chapter 9.) ![]()
Integrate the routing functions of VINES and TCP/IP, which work together to route data between servers. This task involves specifying other servers equipped with the TCP/IP Routing option. (For planning guidelines, see Chapter 5; for instructions, see Chapter 10.) ![]()
Specify other VINES servers with which you wish to establish a connection through a foreign host gateway. This connection allows workstations connected to your server to access VINES services across the TCP/IP foreign host gateway. (For planning guidelines, see Chapter 6; for instructions, see Chapter 11.)
In effect, your task of managing routing begins when you manage IP interfaces and specify other servers running TCP/IP. The TCP/IP configuration program uses the following information to create routing entries:
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The IP addresses you specify for other servers in your server's VINES network. The program uses these addresses to establish routes to networks. ![]()
IP addresses you assign to interfaces on your server. The program can define routes to networks whose numbers appear in the IP addresses you assign to interfaces on your server.
Evaluating a Configuration's Complexity
This section helps you determine the complexity of your TCP/IP configuration. In general, the complexity of a host's TCP/IP configuration depends on the role it plays in routing packets. Routing roles are different for end points and gateways.
An end point needs a gateway to communicate with hosts that are not on the LAN that connects the end point to the network. The gateway must be on the same LAN as the end point.
For routing, the end point needs to know only the addresses of destinations and the default gateway's IP address. Whenever the end point sends a packet to a destination that is not on its connection to the network, the end point sends the packet to the default gateway for routing. Thus, TCP/IP configurations of end points are very simple, requiring little planning.
On the other hand, gateways have multiple interfaces to the network, and must make complex routing decisions when switching packets from one interface to another. Gateways tend to need complex TCP/IP configurations to perform routing functions.
A gateway does not necessarily require a complex configuration. In some cases, you may specify the default gateway only. For example, Server Gateway in Figure 3-2 just needs to know how to reach the workstations directly connected to it, and the default gateway.