Network system having multiple subnets for a mobile platform

A method for assigning Internet Protocol addresses in a communications system for an aircraft according to the invention includes the steps of creating an air-to-ground network (AGN), a passenger services network (PSN), and a command and control network (CCN). A first range of addresses is assigned to a first group of devices that are associated with the AGN. A second range of addresses is assigned to a second group of devices that are associated with the PSN. A third range of addresses is assigned to a third group of devices that are associated with the CCN. IP aliasing is employed to allow at least one device from the first, second and third groups to be multi-homed.

FIELD OF THE INVENTION

The present invention relates to networks for mobile platforms, and more particularly to an Internet Protocol (IP) addressing scheme for mobile platforms.

BACKGROUND OF THE INVENTION

Broadband communications access, on which our society and economy is growing increasingly dependent, is not readily available to users on board mobile platforms such as aircraft, ships, and trains. While the technology exists to deliver the broadband communications services to mobile platforms, conventional solutions are currently commercially unfeasible due to the high costs for service or due to low data rates. The conventional solutions have typically only been available to government/military users and/or to high-end maritime markets such as cruise ships. To attract business users, the broadband communication services must provide acceptable data rates at a reasonable price. The broadband communications services must also be designed within guidelines that are required for networks or nodes that are connected to the Internet.

Internet web sites are identified by a public address. Routers and switches use the public address to route IP packets. Public addresses are considered a scarce resource. Requests for public address space from American Registry for Internet Numbers (ARIN) are scrutinized for efficient usage. For example, aircraft Internet systems will require a significant number of IP addresses for routers, servers, users, and other hosts.

SUMMARY OF THE INVENTION

A method for assigning Internet Protocol addresses in a communications system for an aircraft according to the invention includes the steps of creating an air-to-ground network (AGN), a passenger services network (PSN), and a command and control network (CCN). A first range of addresses is assigned to a first group of devices that are associated with the AGN. A second range of addresses is assigned to a second group of devices that are associated with the PSN. A third range of addresses is assigned to a third group of devices that are associated with the CCN. IP aliasing is employed to allow at least one device from the first, second and third groups to be multi-homed.

In other features of the invention, the first range of addresses define a network number and a host number. The host number is divided into an aircraft number for subnetting and a device number.

In still other features, a second range of addresses includes a network number and a host number. The host number includes a first group of bits that identify one of a seat electronic box device, a server element and a network element. A second group of bits identifies an area distribution box. A third group of bits identifies a column. The host number includes a fourth group of bits that identify a seat electronic box. In a first alternate, the host number includes a fifth group of bits that identify a type of server that is to be addressed and a sixth group of bits that identify a server device. In a second alternate, the host number includes a seventh group of bits that identify a type of network that is to be addressed and an eighth group of bits that identify a network device.

In still other features of the invention, the third range of addresses includes two addresses that are super-netted together. The third range of addresses include a network number and a host number. The host number includes bits that identify an area distribution box, a column, a seatbox, a user, and a port.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now toFIG. 1, a mobile platform communications system10for mobile platforms12-1,12-2, . . . , and12-n is shown. The mobile platforms12communicate via one or more satellites16-1,16-2, . . . , and16-n and with one or more ground-based receiving stations18-1,18-2, . . . , and18-n. The ground-based receiving stations18are connected to a distributed communications system22via a router24-1,24-2, . . . , and24-n. A public address manager (PAM) server28is connected to the distributed communications system22, the router24or to the ground-based receiving stations18. If used, the PAM server28manages the leasing of public addresses that are stored in a public address pool29to the mobile platforms12.

One or more web servers30-1,30-2, . . . , and30-n are connected to the distributed communications system22. Likewise, one or more virtual private networks (VPNs)32-1,32-2, . . . , and32-n are connected to the distributed communications system22. The distributed communications system22is preferably the Internet. Users located on the mobile platform12access the web servers30and/or the VPN's32via the mobile platform communications system10. As can be appreciated, the mobile platform establishes an air-to-ground network via the satellites16and the ground stations18.

Referring now toFIG. 2, the mobile platform12includes a transmit antenna40that is connected by a switch41to a transmitter42and a receive antenna46that is connected by the switch41to a receiver48. The transmit and receive antennas40and46are controlled by an antenna control system50. The receiver48, the transmitter42, the switch41, a switch52and an airborne router54are collectively referred to as a data transceiver router (DTR)55.

The airborne router54is connected to a switch57that is connected to servers64,65,66, and67. The servers64-67provide web services, media services, an aircraft interface unit (AIU), a control panel (CP), and other server functions. For example, the servers provide flight specific websites such as car rental companies located at the destination, popular web sites such as CNN, MSN, etc. that are stored in cache, targeted advertising, and other content. One or more additional servers and/or functions may also be provided. The switch57is connected to one or more area distribution boxes (ADBs)68-1,68-2, . . . , and68-n. The ADBs68are connected to one or more seat processors70that are connected to one or more user communication devices UCD74-1,74-2, . . . , and74-n. A switch69and the seat processor70are collectively referred to as a seat electronic box (SEB)72. The UCD74is a laptop computer, a personal digital assistant PDA, or any other electronic device that communicates via the Internet. The UCDs74preferably include a microprocessor, memory (such as random access memory, read-only memory, and/or flash memory), and input/output devices such as a keyboard, a mouse, and/or a voice operated interface. In a preferred embodiment, the mobile platform communications system10establishes point-to-point over Ethernet (PPPoE) sessions between the UCDs74and the airborne router54.

Referring now toFIG. 3, the communication system10according to the present invention includes three or more logical subnets: a passenger services network (PSN)100, an air-to-ground network (AGN)102and a command and control network (CCN)104. For example, the servers64and66that provide web or media services are preferably multi-homed in that they have multiple physical interfaces. The UCDs74are connected to the PSN100. IP aliasing allows multiple IP addresses to be configured on the same physical interface. The IP addresses can be from the same or different subnets. Multiple logical subnets can be created on the same physical network. Since only a router can forward traffic between subnets, logical subnets simplify router and host-based packet filtering to control inter-subnet access. Logical subnets allow access to actual application ports to be restricted to specific subnets. Logical subnets allow maximum use of private address ranges and reuse of address ranges between module platforms. Logical subnets minimize the number of subnets that must be advertised to the ground.

More particularly, the AGN102is defined as the network that provides connectivity between the onboard IP management interfaces on each network element (such as routers, switches, servers, and seat boxes) and the ground. Data that is expected to use the AGN102includes simple network management protocol (SNMP) traffic, content pushed from the ground to the aircraft, billing information, maintenance data of the network elements, port address translation of passenger addresses for off-board aircraft connectivity and other similar data traffic.

A first part (or network number) of an IP address typically identifies a network on which a host resides. A second part (or host number) identifies the particular host on the network. To support different sized networks, the IP address space is split into three address classes. A Class A IP address typically includes an 8-bit network number and a 24-bit host number. Class A IP addresses are currently assigned a dotted decimal address in the range between 1.xxx.xxx.xxx and 126.xxx.xxx.xxx. A Class B IP address includes a 16-bit network number and a 16-bit host number. Class B IP addresses are currently assigned a dotted decimal address in the range between 128.0.xxx.xxx and 191.255.xxx.xxx. A Class C IP address includes a 24-bit network number and an 8-bit host number. Class C IP addresses are currently assigned a dotted decimal address in the range between 192.0.0.xxx and 223.255.255.xxx.

The AGN102preferably employs a Class A IP address. The host number is further broken down into a subnet number and a sub-host number to more effectively use the IP address space. In the mobile platform addressing scheme according to the invention, the IP addresses for the AGN102include a network number, a subnet number that is equal to an aircraft identification number and a sub-host number that is equal to a device number. The aircraft identification number is a 14-bit number that allows 16,382 aircraft to be uniquely addressed from the ground. This addressing approach provides sufficient address space for commercial passenger aircraft and can also be used to extend this service to additional sectors.

Private addressing is used to reduce the need for public Internet routable IP addresses that are difficult to obtain. The 14-bit aircraft identifier doubles as the subnet number to allow routed communications between the plane and the ground. The second part of the IP address is the device or host number. The device or host number provides 10-bits of device address space. The range of device numbers preferably starts with device number1(the device number0is not used) and ends with the device number1022. These limitations reduce the possibility of assigning an address that conflicts with the broadcast address of the subnet. The device or host numbers are further separated into the ranges listed in the table shown in FIG.4.

Referring now toFIG. 4, a first range, including1to6, is assigned to devices or hosts that route management traffic between the air and the ground. The devices or hosts in the first range preferably include the DTR55and other transmit/receive devices that are located between the air and the ground. A second range, including7and8, is assigned to Port Address Translation (PAT) of onboard passenger addresses to the ground. PAT changes a source IP address and a source port to allow a large number of devices to use a single IP address. Two addresses are used to ensure that PAT does not run out of addresses.

A third range, including9to24, corresponds to a management interface of the ADBs68. A fourth range, including25to424, is used for UCDs74. With this approach, there can be a maximum of 16 ADBs. Each ADB has 5 columns with 30 SEBs. Up to 2400 UCDs74can be supported. This is unlikely to occur if the mobile platform is an aircraft since the maximum number of passengers that are expected for the largest aircraft is 800. 400 addresses have been reserved for UCDs.

A fifth range of addresses, including425to432, corresponds to servers such as the media server64, web server66and/or servers for other services. A sixth range, including433to422, is reserved for crew information system devices. The aircraft interface unit (AIU)65is assigned address443. Control panels (CP)67are assigned a seventh address range including444to450. Laptop power controllers are assigned device addresses in an eighth range including954to969.

To allow for future deployment of expanded services, addresses in a ninth range, including970to989, are reserved for servers and delivery service devices. A tenth range, including990to1005, allows communication between legacy equipment and IP enabled equipment. Business jets have an additional four receivers that are assigned addresses in an 11thrange including1006to1009. Finally, to allow communication between the DTR55and the antenna control/system50in the future, address1010is reserved. The overall address scheme can be summarized as follows:

Command and Control Network

All servers, routers, and SEBs communicate on the command and control network (CCN)104. The CCN104preferably employs a class B IP address with a 16-bit network number and a 16-bit host number. The CNN104is assigned the network number 172.16.0.0. This network has been further partitioned to allow quick identification of elements (the partitioning is not the same as subnetting). The first four bits of the host number are used to identify classes of devices. The first bit is unused and is set equal to 0. The first bit may be used to provide an additional 32,766 addresses to support IP addresses of other equipment that participates on the CCN104. The next three bits following the first bit of the host number are used to define the CCN device that is being addressed. These three bits are referred to as the “L” bits below. For example, the three bits can be defined as follows: “100” is a SEB element; “010” is a server element, and “001” is a network element.

The address [172.16][0100????.????????] is that of the CCN interface of the SEB72, which is used for initialization and onboard control of the SEB72. As with all CCN devices, the first bit is unused and is set equal to 0. The next three bits are used to define the type of CCN device that is being addressed. In the case of the SEB72, the bit pattern is set equal to 100. To uniquely address each SEB72, the next 4 bits are used to define the ADB68that the SEB72is connected to. This will allow up to 16 ADBs68to be described. The first ADB68starts with the number 0. The next 3 bits are used to define the column of the ADB68that the seatbox is connected to. Three bits are used to allow up to 5 columns per ADB68to be addressed. The first column is addressed as 1. The last bits define the position of the SEB72with respect to the column. Five bits are allocated to allow up to 30 seatboxes to be defined. The first seatbox is addressed as 1. This is summarized as follows:

The server element address is the CCN address of any device that provides a service to the PSN100. This may include web servers, content servers and any other server that may be defined in the future. The address is used for initialization, maintenance, and onboard control of the servers and is not part of the PSN100. As with all CCN elements, the first bit is preferably unused and is set equal to 0. The next three bits are used to define the type of CCN device that is being addressed. In the case of a server element, the bit pattern is set to “010”. To allow different types of servers to be defined and identified by IP addresses, the next 7 bits are used to specify the type of server being addressed starting with a type of1.FIG. 5lists on-board server type numbers. The final 5 bits allow up to 31 servers to be defined for each type. The server device number starts at 1. This is summarized as follows:

The network element address is the CCN address of the devices that provides network services, excluding servers or SEBs, to the PSN100. This includes routers, transmitters, receivers, ADBs, AIUs, Business Jet Receivers, ASPACs, HCAs or any other type of network element. This address is used for initialization and onboard control of the network elements and is not part of or accessible to the PSN100. As with all CCN devices, the first bit is preferably unused and is set equal to 0. The next three bits are used to define the type of CCN device that is being addressed. In the case of a network element, the bit pattern is set to 001. To allow different types of network elements to be defined and identified by IP addresses, the next 7 bits are used to specify the type of network element that is being addressed (starting with a type of 1). The final octet allows up to 31 network elements to be defined for each type. The network element device number starts at 1. This is summarized as follows:

Passenger Services Network

The passenger services network (PSN)100is defined as the IP connectivity between the UCD74and the SEB72. The PSN100preferably uses a Class B address with a 16-bit network number and a 16-bit host number. In a presently preferred embodiment, each port (Ethernet or USB) must be uniquely addressed. The IP addresses for the PSN100allow each port to be assigned its own address and a gateway address for the SEB72. The address includes two Class B addresses that are super-netted together.

The first 15 bits make up the prefix. The next 4 bits define the ADB68that the SEB72is connected to. Up to 16 ADBs68can be described (the first ADB68starts with the number 0). The next 3 bits are used to define the column that the SEB72is connected to. Three bits allow up to 5 columns per ADB68to be addressed (the first column is addressed as 1). In addition, the column is not assigned the number 7 because there can never be more than 5 columns per ADB. 5 bits define the position of the SEB72with respect to its column. Five bits are allocated to allow up to 30 SEB72to be defined (the first SEB must be addressed as 1).

The address uniquely identifies the SEB72and can be used to summarize all routes reachable by this SEB72. This significantly reduces the routing table of the airborne router54. The next bit is used to identify whether the address belongs to a SEB72or to a UCD74. The last four bits are used to specify the port that the address corresponds to. This number can range from 1 to 15 for SEBs72and from 18 to 30 for UCD74addresses. This is summarized as follows:

Server and Network Device Addresses

A special range of addresses on the PSN100is set aside for servers and network elements. As stated above, a column is not assigned the address 7. This allows the use of the address range 172.19.252.1 to 172.19.255.254 to address servers and network elements. This address range is further subdivided to specify that the address range 172.19.252.1 to 172.19.253.254 identifies a server element and the address range 172.19.254.1-172.19.255.254 identifies a network element.

These ranges are determined by looking at the bit patterns. The first two octets are set equal to 172.19. Then 6 bits are set to all 1's. Since a column does not have a bit pattern of all 1's, this bit pattern sets aside a range for servers and network devices. The next bit is used to specify whether the device that is addressed is a server or a network device. The last 9 bits uniquely identify the server or network device. This is summarized as follows:

Seat Element Devices

Seat element devices are defined as any IP addressable element that might be found in a seat such as IP telephones, video displays, audio devices, entertainment systems, or any other similar device. All devices participate on the 172.17.0.0, 255.255.0.0 network. The assignment of addresses is left to the provider of the IP addressable seat elements.

As can be appreciated by the foregoing, the IP addressing scheme for mobile platforms according to the invention effectively and efficiently utilizes IP addressing space. Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims.