LANconfig: IP-Router / Routing / Routing-Table
WEBconfig: LCOS menu tree / Setup / IP-Router / IP-Routing-Table
An IP routing table can, for example, look like this
:
| IP address | Netmask | Routing-Tag | Router | Distance | Masquerading | Active |
|---|---|---|---|---|---|---|
| 192.168.120.0 | 255.255.255.0 | 0 | MAIN | 2 | Off | yes |
| 192.168.125.0 | 255.255.255.0 | 0 | NODE1 | 3 | Off | yes |
| 192.168.130.0 | 255.255.255.0 | 0 | 191.168.140.123 | 0 | Off | yes |
What do the various entries on the list mean?
- IP addresses and netmasks This is the address of the destination network to which data packets may be sent and its associated network mask. The router uses the network mask and the destination IP address of the incoming data packets to check whether the packet belongs to the destination network. The route with the IP address '255.255.255.255' and the network mask '0.0.0.0' is the default route. All data packets that cannot be routed by other routing entries are sent over this route.
- Routing Tag With the routing tag the selection of the target route can be controlled more precisely. Therefore not only the target IP address for the selection of the route is detected but also other information, which is joined to the data packets by the firewall. With the routing tag “0” the routing entry is valid for all packets.
- Router
The router transmits the appropriate data packets to the IP address
and network mask to this remote station.
- If the remote station is a router in another network or an individual workstation computer, this is the name of the remote station.
- If the router on the network cannot address the remote station itself, then the IP address of another router which knows the path to the destination network is entered.
- Routes with the entry '0.0.0.0' identify exclusion routes. Data packets for this “zero route“ are rejected and are not routed any further. That way routes which are forbidden on the Internet (private address spaces, e. g. '10.0.0.0'), for example, are excluded from transmission.
- If an IP address is input as router name, this is a locally available router, which is responsible for transfer of the relevant data packets.
- Distance
Number of routers between your own and the destination router. This
value is often equated with the cost of the transmission and used to
distinguish between inexpensive and expensive call paths for wide-area
connections. The distance values entered are propagated as follows:
- All networks which can be reached while a connection exists to a destination network are propagated with a distance of 1.
- All non-connected networks are propagated with the distance entered in the routing table (but with a minimum distance of 2) as long as a free transmitting channel is still available.
- The remaining networks are propagated with a distance of 16 (= unreachable) if there are no longer any channels available.
- Remote stations connected using proxy ARP are an exception to this. These “proxy hosts“ are not propagated at all.
- Masquerading Use the 'Masquerade' option in the routing table to inform the router which IP addresses to use when transferring packets from local networks. For further information see the section .