Managing resources for IP networking

1. A method for using a network device having an operating system instance that operates in a plurality of routing contexts, the method comprising:

associating a first network with a first routing context and a second network with a second routing context, wherein the first context is isolated from the second context;

enabling a first application running on the operating system instance of the network device to select the first routing context by associating the first application with a first routing context number;

enabling a second application running on the operating system instance of the network device to select the second routing context by associating the second application with a second routing context number;

receiving, at the same networking address of the network device, a first message originating from the first network and a second message originating from the second network by the network device;

at a packet ingress processing module in the network device, assigning to the first message either the first routing context number or the second routing context number based on one of a source network interface and a source application socket; and

providing heritability of the first routing context number, wherein the heritability assigns to a child application of the first application a default routing context associated with the first routing context.

2. The method of claim 1 , wherein a socket for at least one of Transport Control Protocol (TCP), User Datagram Protocol (UDP), and raw IP code associated with the operating system instance inherits the first routing context from a process in the first routing context.

3. The method of claim 1 , further comprising:

assigning to the first message the first routing context number, wherein the first message is determined to be associated with the first routing context using the first routing context number; and

assigning to the second message the second routing context number, wherein the second message is determined to be associated with the second routing context using the second routing context number.

4. The method of claim 3 , further comprising:

assigning a first routing table to the first router context, wherein the first routing table is associated with the first context number; and

assigning a second routing table to the second router context, wherein the second routing table is associated with the second context number.

5. The method of claim 1 , wherein the first and second networks are private networks that are isolated from the Internet.

6. The method of claim 1 , wherein information received by the network device from the first network is not provided to the second network by the network device, and wherein information received by the network device from the second network is not provided to the first network by the network device.

7. The method of claim 1 , wherein both the first message and the second message include at least one data packet.

8. The method of claim 1 , wherein the first and second messages are received by the network device using a first network connection initiated by a first process and a second network connection initiated by a second process, respectively, the method further comprising:

assigning to the first process a default first routing context number associated with the first network connection; and

assigning to the second process a default second routing context number associated with the second network connection.

9. The method of claim 8 , wherein the heritability further comprises inheriting the default first routing context by a third process, whose parent is the first process, at the time of creation of the third process.

10. The method of claim 1 , further comprising associating at least one interface to the operating system instance with a routing context.

11. The method of claim 1 , further comprising providing an IP host that is compatible with existing protocols.

12. The method of claim 1 , further comprising running separate operating system instances on a plurality of processors residing on the network device, which implement a single IP host.

13. A system for use with a first network that is associated with a first routing context, and a second network that is associated with a second routing context, the system comprising:

a network device that receives messages from both the first network and second network at a networking address,

wherein the network device is configured

to enable a first application to select the first routing context by associating the first application with a first routing request number, and

to enable a second application to select the second routing context by associating the second application with a second routing context number, and the network device tags the messages to maintain the association with a routing context while being processed by the network device,

the network device implementing a process that assigns either the first routing context number or the second routing context number to at least one of the messages received by the network device at a packet ingress processing module in the network device,

wherein the process inherits a default routing context associated with the first routing context when the process is created by the first routing context; and

a plurality of processors residing in the network device implementing a distributed host, wherein a processor of the plurality of processors implements multiple hosts.