Default Gateway

The default gateway is the intermediate network node on the network or subnet that has addresses for the network IDs of other subnets in the network. When a workstation sends data, the default gateway can forward the packets to other gateways until the data is eventually delivered to its final destination. Gateways are usually computers that are called routers because they are dedicated to directing network traffic.

TCP/IP workstations can each be configured for one default gateway only. This poses an interesting situation for remote workstations that are also connected to an intranet. For example, a computer at a branch office dials in to the corporate network while it is still connected to the branch office network. This type of a workstation is referred to as a multihomed workstation.

When a multihomed computer running Windows NT Workstation or Windows NT Server attempts to access a particular IP address, the destination server is located by using the following process:

• If the destination IP address indicates that it is on the same IP subnet as the workstation's network interface card, then data is sent through the network interface card.
• If the destination IP address indicates that it is not on the same subnet as the workstation's network interface card, then data is sent to the default gateway assigned by the RAS server. The default gateway then locates the destination route on behalf of the remote workstation.

If a default gateway IP address was previously configured for the network interface card, it is ignored by default. If required, the remote workstation can be configured so that the default gateway on the network interface card is used instead of the default gateway on the remote link.