•Minimal routing
A network completely isolated from all other TCP/IP networks requires only minimal routing. A minimal routing table is usually built by ifconfig when the network interfaces are configured. If your network does not have direct access to other TCP/IP networks, and if you are not using subnetting, this may be the only routing table you require.
•Static routing
A network with a limited number of gateways to other TCP/IP networks can be configured with static routing. When a network has only one gateway, a static route is the best choice. A static routing table is constructed manually by the system administrator using the route command. See Figure 4. Static routing tables do not adjust to network changes, so they work best where routes do not change.
Source Host |
|
| Destination Host | ||
Application |
|
| Application | ||
Transport | Gateway | Transport | |||
Destination | Gateway | Destination | Gateway | Destination | Gateway |
192.168.1.0 | 192.168.12.3 | 192.168.1.0 | 192.168.1.5 | 192.168.1.0 | 192.168.1.2 |
192.168.12.0 | 192.168.12.2 | 192.168.12.0 | 192.168.12.3 | default | 192.168.1.5 |
default | 192.168.12.1 | default | 192.168.12.1 |
|
|
Network Access | Network Access | Network Access | |||
192.168.12.2 | 192.168.12.3 | 192.168.1.5 | 192.168.1.2 | ||
| 192.168.12.0 |
| 192.168.1.0 |
| |
Figure 4. Table-Based Routing
•Dynamic routing
A network with more than one possible route to the same destination should use dynamic routing. A dynamic routing table is built from the information exchanged by the routing protocols. The protocols are designed to distribute information that dynamically adjusts routes to reflect changing network conditions. Routing protocols handle complex routing
