Wednesday, July 11, 2007

Static routing is manually performed by the network administrator. The
administrator is responsible for discovering and propagating routes through the
network. These definitions are manually programmed in every routing device in
the environment.

After a device has been configured, it simply forwards packets out the
predetermined ports. There is no communication between routers regarding the
current topology of the network.

In small networks with minimal redundancy, this process is relatively simple to
administer. However, there are several disadvantages to this approach for maintaining IP routing tables:

Static routes require a considerable amount of coordination and maintenance
in non-trivial network environments.

Static routes cannot dynamically adapt to the current operational state of the
network. If a destination subnetwork becomes unreachable, the static routes
pointing to that network remain in the routing table. Traffic continues to be
forwarded toward that destination. Unless the network administrator updates
the static routes to reflect the new topology, traffic is unable to use any
alternate paths that may exist.

Normally, static routes are used only in simple network topologies. However,
there are additional circumstances when static routing can be attractive. For
example, static routes can be used:

To manually define a default route. This route is used to forward traffic when
the routing table does not contain a more specific route to the destination.

To define a route that is not automatically advertised within a network.

When utilization or line tariffs make it undesirable to send routing
advertisement traffic through lower-capacity WAN connections.

When complex routing policies are required. For example, static routes can
be used to guarantee that traffic destined for a specific host traverses a
designated network path.

To provide a more secure network environment. The administrator is aware of
all subnetworks defined in the environment. The administrator specifically
authorizes all communication permitted between these subnetworks.
To provide more efficient resource utilization. This method of routing table
management requires no network bandwidth to advertise routes between
neighboring devices. It also uses less processor memory and CPU cycles to
calculate network paths.

How to add Static route in Linux PC:

1) Adding specific Host: route add -host gw

2) Adding network : route add -net gw netmask

3) Adding default route : route add default gw

4) Adding Multicast routes : route add netmask dev eth2

For more information/Tutorials on networking please visit my other blogs in my profile.