Patent Publication Number: US-2004044756-A1

Title: Method and apparatus for providing management access to devices behind a network address translator (NAT)

Description:
BACKGROUND  
       [0001] The present invention relates to management of devices on a home network; more particularly, the present invention relates to the capability of managing devices on a home network, wherein utilization of a simple network management protocol (SNMP) proxy agent enables access to both private and public address spaces on each side of a network access translator (NAT).  
       [0002] In applications where a network address translator (NAT) is required in order to communicate with the head end, a NAT does not allow simple network management protocol to be utilized. It is, therefore, desirous to provide a means by which private networks may easily communicate using SNMP.  
       SUMMARY  
       [0003] The present invention utilizes a SNMP proxy agent, having access to both private and public address spaces on each side of a NAT, and which provides additional features to a cable operator and further requires no changes in the system standards. 
     
    
    
     BRIEF DESCRIPTION OF THE FIGURE  
     [0004] The sole figure of the present application is a block diagram showing the manner in which private and public address spaces are interfaced in accordance with the principles of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
     [0005] Making reference to the sole FIGURE of the present application, there is shown therein a system  10 , utilizing an SNMP Proxy Agent  12 , for providing capabilities around a NAT  14 , and which provides a full set of management capabilities for a range of device types in the private address space behind NAT  14 .  
     [0006] To accomplish this, an SNMP Proxy Agent  12  is provided, which has access to both private and public addresses on each side of NAT  14 . SNMP Proxy Agent  12  has two network interfaces, i.e., a Network Interface  13 , for connection to the public address space and a Network Interface  15 , for connection to the private address space. The port  12 A, on the public side, is used to send and receive SNMP messages to and from a network management system (NMS), not shown for purposes of simplicity, also in the public address space, and typically located at the multimedia systems operator MSO head end or at the network control center.  
     [0007] The port  12 B, on the private side, is used to send messages in an arbitrary format to the appropriate devices or objects in the private address space. The management station contacts proxy agent  12 , indicating the identity of the foreign device. The proxy agent translates the protocol interactions it received from the management station to interactions supported by the foreign (private) device.  
     [0008] In the system embodiment  10 , NAT  14  is not part of the data flow, but is provided in the system to act as a quasi-transparent address translator for end-to-end applications. In the SNMP proxy agent case, transmission control protocol/user datagram protocol (TCP/UDP) connections are terminated, and appropriate addresses that do not need translating are used.  
     [0009] The SNMP proxy agent  12  can use an approach that provides a separate object identifier (OID) for each managed object or device and, thereby, appear to the management system such that each object has an SNMP agent. A private management information base (MIB) is created for each object class.  
     [0010] The System  10  shows a wide area network (WAN)  16 , and two local area networks  18  (LAN 1 ) and  20  (LAN 2 ), coupled through L 2  switch  22 , directly or through the NAT  14  and Internet Protocol (IP) Forwarder  28 . Addresses that do not require translation are coupled directly from L 2  switch  22  to the proper local area network  18  or  20  (LAN 1  or LAN 2 ). Addresses that do require translation are coupled to the proper local area network  18  or  20  (LAN 1  or LAN 2 ) through NAT  14  and Internet Protocol Forwarder  28 .