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Chapter 4
Routing

Routing configuration is required only if your LAN has existing Routers or Gateways. Otherwise, this Chapter can be ignored.

Overview

While the ISDN Internet Router includes both RIP 1 (Routing Information Protocol 1) and a standard static routing table, these feature can be completely ignored if you do not have a router in your LAN.

Also, if the ISDN Internet Router is only acting as an Internet Gateway for the local LAN segment, you can ignore the "Routing" screen even if your LAN has other Routers.

Generally, you should use either RIP (Routing Information Protocol) OR the Static Routing Table, although it is possible to use both methods simultaneously.

RIP

RIP (Routing Information Protocol) is used by Routers to exchange routing information, and build routing tables in each Router dynamically.

By default, RIP is disabled. Use the following as a guide to determine whether you should enable RIP.

Static Routing

If RIP is not used, an entry in the routing table is required for each LAN segment on your Network, other than the segment to which this device is attached.

The other Routers must also be configured. It is essential that all IP packets for devices not on the local LAN be passed to the ISDN Internet Router, so that they can be forwarded to the Internet. To achieve this, the Routers must be configured to use the ISDN Internet Router as the Default Route or Default Gateway.

Local Router

The local router is the Router installed on the same LAN segment as the ISDN Internet Router. This router requires that the Default Route is the ISDN Internet Router itself. Typically, routers have a special entry for the Default Route. It should be configured as follows.

Destination IP Address
Normally 0.0.0.0, but check your router documentation.
Network Mask
Normally 0.0.0.0, but check your router documentation.
Gateway IP Address
The IP Address of the ISDN Internet Router.
Metric
1

Other Routers

Other routers must use the ISDN Internet Router's Local Router as the Default Route. The entries will be the same as the ISDN Internet Router's local router, with the exception of the Gateway IP Address.

Static Routing Example

Figure 11: Routing Example

For the LAN shown above, with 2 routers and 3 LAN segments, the required entries would be as follows.

For the ISDN Internet Router's Routing Table

The ISDN Internet Router requires 2 entries as follows.

Entry 1 (Segment 1)

Destination IP Address
192.168.1.0
Network Mask
255.255.255.0 (Standard Class C)
Gateway IP Address
192.168.0.100 (ISDN Internet Router's local Router)
Interface
LAN
Metric
1

Entry 2 (Segment 2)

Destination IP Address
192.168.2.0
Network Mask
255.255.255.0 (Standard Class C)
Gateway IP Address
192.168.0.100
Interface
LAN
Metric
2

For Router A's Default Route

Destination IP Address
0.0.0.0
Network Mask
0.0.0.0
Gateway IP Address
192.168.0.1 (ISDN Internet Router's IP Address)

For Router B's Default Route

Destination IP Address
0.0.0.0
Network Mask
0.0.0.0
Gateway IP Address
192.168.1.80 (ISDN Internet Router's local router)

Static Routing Table

On the LAN tab, static routing table entries will appear as in the example screen below.

Figure 12: LAN Tab

Operations

To delete an existing entry:

To create a new entry:

Routing Data

An entry in the routing table is required for each LAN segment on your Network, other than the segment to which this device is attached. The data for each entry is as follows.

RIP

Enable RIP
Check this to enable the RIP (Routing Information Protocol) feature of the ISDN Internet Router.
The ISDN Internet Router supports RIP 1 only.

Static Routing Table

Select Entry
This drop-down list shows all entries in the Routing Table.
  • To view or change an entry, select it, then click the Get Data button.
  • After making any required changes, click the Update button to save your changes.
Destination
IP Address
The network address of the remote LAN segment.
For standard class "C" LANs, the network address is the first 3 fields of this Destination IP Address. The 4th (last) field can be left at 0.
Network Mask
The Network Mask used on the remote LAN segment. For class "C" networks, the standard Network Mask is 255.255.255.0
Gateway
IP Address
The IP Address of the Router on the LAN segment to which this device is attached. (NOT the router on the remote LAN segment.)
Interface
Select the appropriate interface - LAN (Internal LAN) or WAN (External LAN or WAN) from the drop-down list.
Metric
The number of routers which must be traversed to reach the remote LAN segment. The default value is 1.



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