Ip Routing; How Packets Are Routed; Routing Tables - Lantronix SCS Reference Manual

IP
The entire security table can be cleared with the following command.
Local>> CLEAR IP SECURITY ALL

6.7 IP Routing

TCP/IP internets are usually broken down into networks. Each host on a particular network can only see
hosts on its network; to transfer network traffic to other networks, routers (also called gateways) are
required. Routers are typically connected to two or more networks.
The SCS serves as a router for the networks that it is directly connected to. To determine the path to other
routers on the network, the SCS will listen to network broadcast packets (for example, RIP packets); routers
will advertise themselves in these packets.
The SCS must be positioned between two networks in order for routing to work correctly. If two or more
SCSs are used, the units cannot be on the same network (as in Figure 6-44).
1 2 3 4 5 6 7

6.7.1 How Packets are Routed

When an IP host tries to send a packet, it looks to see if the destination address is on the same network as
the host's IP address. If it is, the host sends the packet directly to its destination. If the packet is destined for
a different network, the host sends it to a router (in this case, the SCS).
When the SCS receives the packet, it examines the packet's destination address, determines the most
efficient route to this address, and forwards the packet to this location. The "most efficient route" is
determined using two factors: the network that the address is part of and the SCS routing table, which is
discussed in the following section.

6.7.2 Routing Tables

The SCS uses a routing table to keep track of which networks are reachable, and the shortest route to each
network. A typical routing table entry consists of the destination network, and which router is the best path
to that network. Routing tables also keep track of the cost or metric required to get to a given network.
6.7.2.1 Types of Routes
There are three types of routes: host, network, and default.
Figure 6-43: Clearing the Security Table
Figure 6-44: Two Units Used to Link the Same Network
192.1.1.1
receive
activity ok 100 link power
transmit
reset # aui 10/100
8 9 10 11 12 13 14 15 16
192.1.1.5
receive
transmit
1 2 3 4 5 6 7 8
6-19
IP Routing
activity ok 100 link power
reset # aui 10/100
9 10 11 12 13 14 15 16