TOPOLOGY DISCOVERY OF A PRIVATE NETWORK

• US 20110141944A1
• Filed: 01/12/2011
• Published: 06/16/2011
• Est. Priority Date: 02/15/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Feng, FuJen, Chow, Ming
• Granted Patent: US 8,787,207 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 41/122 of virtualised topologies, e.g. software-defined networks [SDN] or network function virtualisation [NFV]
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 61/2571 for identification, e.g. for authentication or billing charging arrangements H04L12/14

Abstract

The present invention relates to a method and system for determining devices connected to a private network through a gateway. A Network Management System (NMS) through the use of inquiries and Port Address Translation (PAT) commands is able to determine the topology of the network of devices within a private network and thus communicate with them. This is achieved through the use of Port Address Translation (PAT) initiated by the NMS to set a port for each device connected to the gateway.

Claims

1. A gateway device comprising:

a public interface associated with a primary public Internet Protocol (IP), address discoverable by other network devices and a secondary public IP address, wherein the secondary public IP address is particularly for discovery by a Network Management Server (NMS); and

one or more processors, wherein the one or more processors are configured to;

receive a discovery request from the NMS transmitted to the primary public IP address, the discovery request including a request to identify one or more devices of a private network, wherein the NMS is not in the private network;

identify a private IP address for each of the one or more devices to the NMS; and

responsive to a request from the NMS to add a Port Address Translation (PAT) entry for each of the one or more devices, generate a PAT table corresponding to the secondary public IP address, wherein the request designates a corresponding port for communication with each of the one or more devices selected from unassigned ports and wherein PAT entries include the private IP addresses and corresponding designated ports.

2. The gateway device of claim 1, wherein the one or more processors are further configured to search an access control list or a command authorization list, or combinations thereof upon receipt of a discovery request from the NMS.

3. The gateway device of claim 2, wherein the one or more processors are further configured to permit access only to NMS identified in the access control list or authorized administrators of the gateway device or combinations thereof.

4. The gateway device of claim 3, wherein the one or more processors are further configured to permit commands from the NMS only if the commands are listed in the command authorization list.

5. The gateway device of claim 1, wherein the one or more processors are further configured to compare a first community string value with a second community string value, wherein the second community string value is received in the discovery request.

6. The gateway device of claim 5, wherein if the first community string value and the second community string value do not match, the gateway device ignores the discovery request.

7. A method comprising:

discovering a gateway device, wherein the gateway device is in communication with a private network;

sending a first Simple Network Management Protocol (SNMP) message to the gateway device, wherein the first SNMP message is configured to elicit information about other devices connected to the gateway device;

receiving a message from the gateway device indicating that the gateway device is connected to a private network device;

deducing from the message that the private network device is part of the private network and has a private address; and

sending a command to the gateway device to establish a static PAT entry corresponding to the private network device on the gateway device designate a first port for communication with the private network device.

8. The method of claim 7, further comprising:

sending a second SNMP message to the gateway device, wherein the second SNMP message is configured to communicate with the private network device for requesting information associated with other private network devices in the private network;

responsive to the second SNMP message, receiving information from the private network device associated with at least one of the other private network devices; and

sending a second command to the gateway device to establish a second static PAT entry corresponding to the private network device on the gateway device and to designate a second port for communication with the at least one other private network device.

9. The method of claim 8, further comprising determining that the private network address is accessible, wherein if the private address is accessible then requesting information associated with the other private network devices in the private network.

10. The method of claim 9, further comprising sending a ping or third SNMP message to the private address of the private network device to determine if the private network device is reachable.

11. The method of claim 8, wherein the other private network devices are in communication with the private network device.

12. The method of claim 8, wherein the other private network devices are neighboring the private network device

13. The method of claim 8, further comprising sending a third command to remove one or more static PAT entries on the gateway device subsequent to discovery of the at least one of the other private network devices.

14. The method of claim 8, further comprising mapping the discovered private network device and at least one of the other private network devices in a database.

15. The method of claim 8, further comprising identifying an infrequently used port range and selecting the first designated port and the second designated port from the infrequently used port range.

16. The method of claim 8, further comprising:

accessing a port address table received from the gateway device;

identifying ports that are currently unused from the table; and

selecting the first designated port and the second designated port from the identified unused ports.

17. The method of claim 8, further comprising determining whether the gateway device is configured with a secondary public IP address, wherein the secondary address is for use of an NMS.

18. The method of claim 17, wherein if the NMS discovers that the gateway device is configured with the second public IP address then using the secondary address and an unassigned number from an infrequently used port range to configure PAT.

19. An apparatus comprising:

means for receiving a discovery request from a Network Management System (NMS), wherein the discovery request includes a request to identify a first device of a private network, and wherein the NMS is not part of the private network;

means for identifying the first device;

means for transmitting a first private IP address for the first device to the NMS;

means for receiving an access request from the NMS to add a first Port Address Translation (PAT) entry for the first device, wherein the access request includes the first private IP address and designates a first port for communication with the first device;

means for receiving a second discovery request from the NMS to identify a second device of the private network known by the first device;

means for identifying the second device;

means receiving a second access request for adding add a second PAT entry for the second device, wherein the access request includes a second private IP address and designates a second port for communication with the second device;

means for adding the first PAT entry and the second PAT entry to a translation table, wherein the first PAT entry and the second PAT entry include respective the first private IP address and the second private IP address and respective the first designated port and the second designated port;

means for communicating the translation table to the NMS; and

means for removing the PAT entries.

20. The apparatus of claim 19, wherein the first and second access requests are accompanied by a password, and further comprising means for verifying the passwords prior to adding the first and second PAT entries to a translation table.