Methods and apparatus for optimizing NAT traversal in Mobile IP

In a Home Agent, a method of processing a registration request, comprising:

• receiving a registration request from a network device supporting Mobile IP, the registration request identifying a Mobile Node;
• sending a registration reply across a NAT device performing Network Address Translation to the network device supporting Mobile IP, the registration reply identifying the Mobile Node;
• receiving a keep alive message addressed to the Home Agent from the network device supporting Mobile IP across the NAT device performing Network Address Translation, wherein the keep alive message is not a registration request message;
• and
• dropping the keep alive message without sending a reply to the network device supporting Mobile IP in response to receiving the keep alive message, wherein the message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for a source IP address identified in the keep alive message, wherein the source IP address is a private IP address.

In a Home Agent, a method of processing a registration request, comprising:

• receiving a registration request from a network device across a NAT device performing Network Address Translation, the registration request identifying a Mobile Node;
• sending a registration reply to the network device across the NAT device performing Network Address Translation, the registration reply identifying the Mobile Node;
• and
• receiving a keep alive message addressed to the Home Agent from the network device, wherein the keep alive message is not a registration request message, wherein the keep alive message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for a source IP address identified in the keep alive message, wherein the source IP address is a private IP address.

A computer-readable storage medium storing thereon computer executable instructions for causing a network device supporting Mobile IP to send a message to a Home Agent enabling a NAT device to maintain an entry in a Network Address Translation table for a source IP address identified in the message, comprising:

• instructions for composing a registration request message identifying a Mobile Node;
• instructions for sending the registration request message to the Home Agent across a NAT device performing Network Address Translation;
• instructions for receiving a registration reply message from the Home Agent across the NAT device performing Network Address Translation;
• and
• instructions for sending a keep alive message to the Home Agent after sending the registration request message, wherein the keep alive message is addressed to the Home Agent, wherein the keep alive message is not a registration request message, wherein the message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for the source IP address identified in the keep alive message.

A network device supporting Mobile IP configured for sending a message to a Home Agent enabling a NAT device to maintain an entry in a Network Address Translation table for a source IP address identified in the message, comprising:

• means for composing a registration request message identifying a Mobile Node;
• means for sending the registration request message to the Home Agent across a NAT device performing Network Address Translation;
• means for receiving a registration reply message from the Home Agent across the NAT device performing Network Address Translation;
• and
• means for sending a keep alive message to the Home Agent after sending the registration request message, wherein the keep alive message is addressed to the Home Agent, wherein the keep alive message is not a registration request message, wherein the message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for the source IP address identified in the keep alive message.

A network device supporting Mobile IP configured for sending a message to a Home Agent enabling a NAT device to maintain an entry in a Network Address Translation table for a source IP address identified in the message, comprising:

• a processor;
• and
• a memory, at least one of the processor and the memory being configured for:
• composing a registration request message identifying a Mobile Node;
• sending the registration request message to the Home Agent across a NAT device performing Network Address Translation;
• receiving a registration reply message from the Home Agent across the NAT device performing Network Address Translation;
• and
• sending a keep alive message to the Home Agent after sending the registration request message, wherein the keep alive message is addressed to the Home Agent, wherein the keep alive message is not a registration request message, wherein the message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for the source IP address identified in the keep alive message.

A Home Agent, comprising:

• a processor;
• and
• a memory, at least one of the processor or the memory being configured for:
• receiving a registration request from a network device supporting Mobile IP, the registration request identifying a Mobile Node;
• sending a registration reply across a NAT device performing Network Address Translation to the network device supporting Mobile IP, the registration reply identifying the Mobile Node;
• receiving a keep alive message addressed to the Home Agent from the network device supporting Mobile IP across the NAT device performing Network Address Translation, wherein the keep alive message is not a registration request message;
• and
• dropping the keep alive message without sending a reply to the network device supporting Mobile IP in response to receiving the keep alive message, wherein the message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for a source IP address identified in the keep alive message, wherein the source IP address is a private IP address.

A Home Agent, comprising:

• a processor;
• and
• a memory, at least one of the processor or the memory being configured for:
• receiving a registration request from a network device across a NAT device performing Network Address Translation, the registration request identifying a Mobile Node;
• sending a registration reply to the network device across the NAT device performing Network Address Translation, the registration reply identifying the Mobile Node;
• and
• receiving a keep alive message addressed to the Home Agent from the network device, wherein the keep alive message is not a registration request message, wherein the keep alive message is sent in order to enable the NAT device to maintain an entry in its Network Address Translation table for a source IP address identified in the keep alive message, wherein the source IP address is a private IP address.