Configuring the IS-IS Intermediate System as Overloaded

There are some circumstances in which it is advantageous to have an IS-IS intermediate system not fully participate in forwarding traffic. For example:

• During startup this intermediate system may be temporarily too busy with the tasks associated with convergence to forward traffic.
• The intermediate system is in a test network that has connections to a production network. The overload bit prevents traffic from moving between the two networks.

You can configure the intermediate system to not forward traffic by enabling the overload bit.

When enabled, the overload bit instructs other intermediate systems not to use this intermediate system as an intermediate hop in their SPF computations. No paths through this intermediate system are visible to other intermediate systems in the domain. IP and CLNS prefixes directly connected to this intermediate system are reachable.

Use the set-overload-bit command in IS-IS configuration mode to enable overload on this intermediate system.