US20150257081A1

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Publication number: US20150257081A1
Application number: US14/613,894
Authority: US
Inventors: Ranga Sri Ramanujan; Ben Burnett; Barry A. Trent; Jafar Al-Gharaibeh
Original assignee: Architecture Technology Inc
Current assignee: Architecture Technology Inc
Priority date: 2014-02-04
Filing date: 2015-02-04
Publication date: 2015-09-10
Also published as: US10728149B1

Abstract

A single routable network and an integrated router having a plurality of network interfaces for such network having a plurality of heterogeneous subnetworks having different network parameters, each of the plurality of network interfaces configured to be connected to a different one of the plurality of heterogeneous subnetworks. The integration router is configured to automatically connect with each of the plurality of heterogeneous subnetworks. The integration router providing persistent network connectivity between user nodes across the plurality of heterogeneous subnetworks

Description

RELATED APPLICATION

This application claims priority from U.S. Provisional Application No. 61/935,661, filed on Feb. 4, 2014 entitled “HYBRID AUTONOMOUS ROUTER FOR TACTICAL COMMUNICATION”.

GOVERNMENT CONTRACTS

This invention was made with government support under contract FA8750-12-C-0213 awarded by the Air Force Research Laboratory (AFRL) Small Business Innovation Research (SBIR). The government has certain rights in the invention.

TECHNICAL FIELD

The present invention relates to networking systems and components in general and, more particularly to networking systems and components having an ability to connect heterogeneous wireless networks.

BACKGROUND

Various networking systems, protocols and networking equipment and software exist to connect various discrete components together into a communication network.

However, existing networking approaches are incapable of integrating heterogeneous wireless networks. Such existing networks have:

- (1) inability to adapt dynamically to topology changes in the network;
- (2) need for excessive manual configuration;
- (3) lack of scalability with network size;
- (4) inability of routing protocols to factor wireless link quality into routing decisions, resulting in sub-optimal network performance.

SUMMARY

A hybrid router, an autonomous IP based network integration solution that provides end-to-end sensor-to-shooter connectivity across a heterogeneous tactical network is disclosed. This network consists of IP sub-networks of various types such as TTNT (Tactical Targeting Network Technology), mini-CDL (Common Data Link), free space optics communications (FSOC), QNT (Quint Networking Technology), and JCAN (Joint Capability for Airborne Networking). These integrated networks provide improved tactical communications and situational awareness. Network integration is the convergence of many IP devices (wired, wireless, radio, optical) each forming IP subnets into a single IP network. Each of the device subnets may be IP capable on their own, but cannot integrate seamlessly and automatically with others.

In an embodiment, a single routable network has a plurality of heterogeneous subnetworks having different network parameters and an integration router containing a plurality of network interfaces, each of the plurality of network interfaces configured to be connected to a different one of the plurality of heterogeneous subnetworks. The integration router is configured to automatically connect with each of the plurality of heterogeneous subnetworks. The integration router providing persistent network connectivity between user nodes across the plurality of heterogeneous subnetworks.

In an embodiment, the integration router is configured to automatically connect with each of the plurality of heterogeneous subnetworks without individual manual configuration of parameters associated with each of the plurality of heterogeneous subnetworks.

In an embodiment, the integration router is configured to provide dynamic route selection between a first node on one of the plurality of heterogeneous subnetworks and a second node on another of the plurality of heterogeneous subnetworks.

In an embodiment, the integration router provides dynamic route selection between the first node on the one of the plurality of heterogeneous subnetworks and the second node on the another of the plurality of heterogeneous subnetworks based on a quality of service.

In an embodiment, the integration router dynamically configures a route selection between the first node on the one of the plurality of heterogeneous subnetworks and the second node on the another of the plurality of heterogeneous subnetworks based on a proactive failover based on degradation of service quality before route communication failure.

In an embodiment, the integration router provides dynamic route selection between the first node on the one of the plurality of heterogeneous subnetworks and the second node on the another of the plurality of heterogeneous subnetworks based on a balancing loads over different routes between the first node on the one of the plurality of heterogeneous subnetworks and the second node on the another of the plurality of heterogeneous subnetworks.

In an embodiment, the integration router further comprises a BGP-MX module configured to dynamically discover BGP peers across the plurality of heterogeneous subnetworks.

In an embodiment, the BGP-MX module is further configured to automatically and dynamically establish and adjust a route between the first node on the one of the plurality of heterogeneous subnetworks and the second node on the another of the plurality of heterogeneous subnetworks.

In an embodiment, the integration router is configured to be integrated with a conventional software router.

In an embodiment, the integration router is configured to be integrated within the conventional software router.

In an embodiment, the integration router is configured as an add-on module to a conventional software router.

In an embodiment, the integration router is configured to be programmed within a programmable processing appliance.

In an embodiment, the integration router has an autonomous router configuration module configured to be operatively coupled to a conventional router, a dynamic address map providing topology and address tracking, and a device configuration interface configured to be coupled to each of the plurality of heterogeneous subnetworks.

In an embodiment, each of the plurality of heterogeneous subnetworks are separate autonomous systems.

In an embodiment, a single network has a plurality of heterogeneous subnetworks having different network parameters and a plurality of integration routers containing a plurality of network interfaces, each of the plurality of network interfaces configured to be connected to a different one of the plurality of heterogeneous subnetworks. The integration router is configured to automatically connect with each of the plurality of heterogeneous subnetworks. The integration router providing persistent network connectivity between user nodes across the plurality of heterogeneous subnetworks. A first type of the plurality of integration routers is configured as an interior router to be installed a backbone nodes providing routing to and from a first node on one of the plurality of network interfaces and a second node on another of the plurality of network interfaces. A a second type of integration router is configured as an edge router providing routing to and from a node located on one of the plurality of network interfaces. A third type of integration router is configured as a gateway router to be installed a backbone nodes providing routing to and from a first node on one of the plurality of network interfaces and a second node on another of the plurality of network interfaces and to provide links to a global information grid.

In an embodiment, an integration router configured for use on a single routable network having a plurality of heterogeneous subnetworks having different network parameters. The integration router containing a plurality of network interfaces, each of the plurality of network interfaces configured to be connected to a different one of the plurality of heterogeneous subnetworks. The integration router is configured to automatically connect with each of the plurality of heterogeneous subnetworks. The integration router provides persistent network connectivity between user nodes across the plurality of heterogeneous subnetworks.

In an embodiment, the integration router is further configured to automatically and dynamically establish and adjust a route between the first node on the one of the plurality of heterogeneous subnetworks and the second node on another of the plurality of heterogeneous subnetworks.

DRAWINGS

FIG. 1 illustrates an embodiment of an airborne network built from mixed IP devices;

FIG. 2ais a block diagram of hardware of a router constructed in accordance with an embodiment of the present invention;

FIG. 2bis an illustration of the software architecture of a router constructed in accordance with an embodiment of the present invention;

FIG. 3 is a diagram of an airborne network with routers constructed in accordance with an embodiment of the present invention;

FIG. 4 is a block diagram of software architecture of the present invention;

FIG. 5 is a conceptual view of a router constructed in accordance with an embodiment of the present invention containing multiple interfaces;

FIG. 6 illustrates the black side of a notional multi-subnet airborne network;

FIG. 7 is an illustration of routers constructed in accordance with an embodiment of the present invention placed in a multi-subnet airborne network;

FIG. 8 is a more detailed block diagram of the software architecture of a router constructed in accordance with an embodiment of the present invention;

FIG. 9 is an illustration of an initial state of an embodiment of multi-subnet network;

FIG. 10 is an illustration of the multi-subnet network ofFIG. 9 as a UAV joins the network;

FIG. 11 is an illustration of the multi-subnet network ofFIG. 10 afterstep 4 of the UAV joining the network;

FIG. 12 is an illustration of the multi-subnet network ofFIG. 11 with completed alias-tag tables;

FIG. 13 is an illustration of the multi-subnet network showing an example of a data path route;

FIG. 14 is an illustration of the multi-subnet network showing dynamic failover and rerouting along a different path;

FIG. 15 is a detailed architecture overview of a router constructed in accordance with an embodiment of the present invention;

FIG. 16 illustrates an alias tag table entry;

FIG. 17 is an illustration of a completed alias tag table;

FIG. 18 is an example of the format of a policy table entry;

FIG. 19 is an illustration of the multi-subnet network with a UAV scenario;

FIG. 20 is a block diagram of an AV network configuration illustrating ports available on a router constructed in accordance with an embodiment of the present invention;

FIG. 21 is a block diagram of a router constructed in accordance with an embodiment of the present invention utilized as a ground control station coupled to the internet;

FIG. 22 is a block diagram of an embodiment of the software architecture of a router constructed in accordance with an embodiment of the present invention;

FIG. 23 is an illustration of test bed utilizing routers constructed in accordance with an embodiment of the present invention;

FIG. 24 is a diagram illustrating steps utilizing link quality monitoring and proactive link failover;

FIG. 25aandFIG. 25billustrate routers constructed in accordance with an embodiment of the present invention installed in a test bed with mini-CDL radios;

FIG. 26ais a diagram illustrating how data is routed in the absence of load balancing;

FIG. 26bis a diagram illustrating data flow balanced across available links;

FIG. 27 is an illustration of one scenario of maximized network performance;

FIG. 28 is an illustration of a second scenario of maximized network performance;

FIG. 29,FIG. 30 andFIG. 31 are diagrams illustrating subnet convergence function with link quality monitoring;

FIG. 32 is a diagram illustrating flow control;

FIG. 33 is a diagram illustrating bandwidth and latency monitoring;

FIG. 34 is a diagram illustrating packet loss detection;

FIG. 35 andFIG. 36 are diagrams illustrating subnet convergence function utilizing flow control;

FIG. 37 andFIG. 38 are diagrams illustrating subnet convergence utilizing traffic redirection;

FIG. 39 andFIG. 40 are diagrams illustrating quality of service aware unicast routing service;

FIG. 41 andFIG. 42 are diagrams illustrating mobility management function;

FIG. 43 andFIG. 44 are diagrams illustrating load balancing function;

FIG. 45 is a diagram illustrating a test in which redundant paths between subnetworks are created and on the paths is impaired;

FIG. 46 is a diagram illustrating a test which recreates redundant links and verifies load balancing enhancing multicast efficiency;

FIG. 47 is a diagram illustrating a test platform for network aware, traffic aware; proactive failover and load balancing;

FIG. 48 is a diagram illustrating a use case of routers constructed in accordance with an embodiment of the present invention showing an initial state and setup before join;

FIG. 49 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 1);

FIG. 50 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 2);

FIG. 51 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 3);

FIG. 52 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 4);

FIG. 53 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 5);

FIG. 54 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 6);

FIG. 55 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 7);

FIG. 56 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 8);

FIG. 57 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 9);

FIG. 58 is a diagram illustrating the use case ofFIG. 48 when a node joins the network (step 10);

FIG. 59 is a diagram illustrating the use case ofFIG. 48 when a node joins the network showing completed table entries;

FIG. 60 is a diagram illustrating a use case of routing a packet (step 1);

FIG. 61 is a diagram illustrating the use case ofFIG. 60 routing a packet (step 2);

FIG. 62 is a diagram illustrating the use case ofFIG. 60 routing a packet (step 3);

FIG. 63 is a diagram illustrating a use case of routing a packet;

FIG. 64 is a diagram illustrating a use case of re-routing a packet (step 1);

FIG. 65 is a diagram illustrating the use case ofFIG. 64 re-routing a packet (step 2);

FIG. 66 is a diagram illustrating the use case ofFIG. 64 re-routing a packet (step 3);

FIG. 67 is a diagram illustrating a use case of routing a packet illustrating a return path;

FIG. 68 is a diagram illustrating a use case of routers constructed in accordance with an embodiment of the present invention showing a node moving from one TTNT subnet to another TTNT subnet;

FIG. 69 is a diagram illustrating a use case of routers constructed in accordance with an embodiment of the present invention showing routing using replication and balancing;

FIG. 70 is a diagram illustrating a use case of routers constructed in accordance with an embodiment of the present invention showing a link fault while routing data;

FIG. 71 is a diagram illustrating a use case of routers constructed in accordance with an embodiment of the present invention showing routing of control messages; and

FIG. 72 is a diagram illustrating a use case of routers constructed in accordance with an embodiment of the present invention showing routing of control messages with link failure.

DESCRIPTION

The entire content of U.S. Provisional Application Ser. No. 61/935,661, filed Feb. 4, 2014 is hereby incorporated by reference.

The Hybrid Autonomous Router for Tactical Networks (HART) is a self-configuring integration router software module that interconnects heterogeneous subnets of differing IP devices into a single routable network implemented for integration with a mini-CDL radio.

The HART integration router is a software tool that can be added into existing commercial routers on an add-on card, integrated into software routers such as quagga or vyatta, or can be installed in a network appliance where data is sent through the appliance. These HART Integration Routers may be installed on appliances and nodes throughout the black-side of a network.

Many different wireless networking technologies are currently used to build airborne networks today. These wireless networks operate on different frequencies, use different waveforms, and provide limited autonomous switching and routing capability. This is shown inFIG. 1.

Existing approaches for integrating these heterogeneous wireless networks suffer from four major limitations overcome by the HART approach:

- (5) inability to adapt dynamically to topology changes in the network;
- (6) need for excessive manual configuration;
- (7) lack of scalability with network size;
- (8) inability of routing protocols to factor wireless link quality into routing decisions, resulting in sub-optimal network performance.

HART addresses two major technical challenges that remain unaddressed by the state of the art to achieve the desired capability of an autonomous integration router for tactical edge networks:

- 1. Autonomous Mission Persistent Network Connectivity, i.e., the development of a scalable and automatic approach for establishing and maintaining end-to-end connectivity between user nodes in a dynamically changing tactical network topology with intermittent connectivity to the global information grid (“GIG”).
- 2. Autonomous Mission Optimized Network Connectivity, i.e. the development of an enhanced tactical routing approach that is aware of the dynamic changes in the quality of wireless links within the tactical network and that factors link quality into its computation of end-to-end routes to optimize network and mission performance.

FIG. 2ashows a block diagram of the hardware where the integration router (HART) contains multiple interfaces, i.e., a LAN interface connected to a HAIPE-fronted platform LAN and WAN interfaces connected to different wireless terminals, e.g., TTNT, QNT, mini-CDL, FSO). Some of these wireless terminals implement bridged IP subnets (e.g., mini-CDL, FSO) while others implement routed IP subnets using proprietary routing protocols (e.g., TTNT, QNT). The software architecture of the HART integration router, shown inFIG. 2b, consists of a core OSPF routing function with plug-in router extensions for each type of wireless terminal. The terminal-specific router extensions implement the HART innovations listed above to enable performance-optimized routing across the heterogeneous collections of bridged and routed IP subnets.

The HART approach has two major beneficial features:

- 1. It requires no modifications to the software of existing tactical IP radios and optical modems to deliver its network integration and enhanced tactical routing capabilities. This facilitates rapid deployment of the technology in the field by eliminating the need to coordinate software changes with the various vendors of wireless IP terminals.
- 2. It lends itself to a modular implementation architecture where the HART mechanism and techniques are implemented as plug-in software modules that can either be (1) integrated within existing software routers (e.g., quagga, XORP); or (2) executed on add-on processor modules for commercial hardware routers (e.g., within an AXP card for a Cisco router); or (3) integrated within commercially-available programmable high-speed packet processing appliances (e.g., EZappliance).

Underlying the HART approach for network integration and enhanced tactical routing is a set of innovative techniques and mechanisms that will be implemented within software module that can be installed either as an add-on to existing routers, or as a network appliance within existing networks. To address the challenges and capability gaps described above, the HART software may provide these capabilities:

- Hybrid routing;
- Quality-aware routing;
- Integration with existing Sub-networks.

Hybrid Routing

HART employs a hybrid routing approach to establish and maintain end-to-end connectivity between nodes in a mobile tactical network environment. It employs a direct routing approach for connecting nodes within the tactical AS (Autonomous Systems) and uses a mobile IP based overlay routing approach with tactical enhancements for connecting tactical nodes to nodes in the GIG. The enhanced Mobile IP based technique eliminates the packet encapsulation overhead associated with overlay routing when packets traverse the bandwidth-constrained tactical user sub-nets. The HART Hybrid routing addresses both:

- Intra-Tactical-AS Routing;
- Routing between the Tactical-AS and the GIG.

Quality-Aware Routing

The proposed approach for enhanced tactical routing is based on dynamic route selection using link quality and using optical and other link types as failover links when primary links failed or degraded. This is now expanded to become more generic to allow more flexibility for Quality aware routing. HART tracks link quality using network monitors, link probes and other techniques. This quality-aware link monitoring will be used to calculate a Link Quality Metric (LQM). The LQM will be stored in HART and updated in the router on the HART machine adding quality-aware routing to existing routers (which do not have a way to monitor and probe the link quality).

Integration with existing Sub-networks

The HART module integrates with existing subnets and gateways (e.g.

JCAN: Joint Capability for Airborne Networking and BACN: Battlefield Airborne Communications Node)as a separate AS (Autonomous Systems). It uses the innovative BGP-MX (BGP with Mobility Extensions) service to exchange network reachability information with these other ASes. BGP-MX overcomes static manual configuration of BGP peering arrangements by implementing mechanisms that enable transit routers in a mobile AS environment to (1) dynamically discover BGP peers from a different AS and automatically establish a peering relationship; and (2) converge rapidly to a new route in response to changes in the topology of the backbone networks.

Discussion

The HART approach can be used for network integration and enhanced tactical routing in a heterogeneous tactical networking environment. The HART approach may be used to enhance the following:

- Analyze Network Integration Requirements;
- Develop Design of Protocols and Services;
- Evaluate Performance using Simulations;
- Develop Product Implementation Architecture.

Analysis

Use cases of diverse multi-subnet environments and situations have been created such as: nodes joining or leaving a network; or nodes moving from one network (using TTNT) to another network (using Mini-CDL). Other use cases involved requested data flows from the ground to an aerial node, the reverse, and data flows from aerial node to aerial node. Some of these Use Cases are included in Appendix B below.

In various embodiments, HART solves:

- No changes to existing radios and COTS routers;
- Provide GIG to Airborne Network (AN) endpoint connectivity (and reverse);
- Provide GIG to Airborne Network (AN) endpoint connectivity (and reverse);
- Provide quality aware link and route selection.

These use cases were analyzed to determine what an integration router monitors, and what network dynamics are tracked, and what options are configured in existing hardware (routers and radios).

The HART design is refined by analyzing several real-world use cases of multi-subnet environments with different radio and routing capabilities.

After the design was refined, a subset of functionality was selected to create a prototype to demonstrate the HART approach. The features selected for prototyping were proactive failover across many links and integration with a Mini-CDL radio and interface. With the proactive failover mechanism, the HART router monitors the quality of each radio link to detect when it falls below a specified threshold. Upon detection of unacceptable link degradation, the HART router proactively routes all IP packet flows traversing the degraded link to a backup link of higher quality. If or when the original link recovers its quality, the IP packet flows are switched back to this link. Current systems provide no capability for proactive link failover; failover occurs only after a complete breakdown of a link. Application performance suffers as a consequence. In addition to proactive link selection, the HART prototype implements multi-level policy-based failover (1, 2, 3, 4, 5 or more backup links in a prioritized order), a capability that is not supported within COTS routers. For instance, with conventional routers, if the policy route for an IP flow were to fail it will be routed over the default interface. Unlike HART, secondary and tertiary policy routes cannot be specified with conventional routers.

HART Overview

Network integration is the convergence of many IP devices (wired, wireless, radio, optical) each forming IP subnets into a single IP network. Each of these device subnets may be IP capable on their own, but cannot integrate seamlessly and automatically with others. Appendix A outlines the list of IP device targets, the interface method, and device subnet integration.

HART software provides heterogeneous network integration. HART addresses these problems by integrating the following techniques into Autonomous Integration Routers:

- Hybrid routing;
- Dynamic subnet domain name service;
- Quality-aware link monitoring and routing; and
- Mobility-enhanced BGP (or BGP-MX).

These HART Integration Routers may be installed throughout the black-side network, as shown inFIG. 3.

The HART integration router is a software tool that can be added into existing commercial routers on an add-on card, integrated into software routers such as quagga or vyatta, or can be installed in a network appliance and where data is sent through the appliance.

The HART software module has six components shown in 4.FIG. 4 also shows the data flow between each of these components. The components are:

- Topology and Address Tracking (TAT)—Dynamic Address Map;
- Autonomous Router Configuration (ARC) Module;
- Device Configuration Interfaces (DCI);
- HART Policy Editor;
- BGP-MX module;
- Router.

Core Network Integration Requirements

This section describes what configuration options to route IP packets on tactical networks. Each end node has an IP address and default route/router and the routers track routes to other subnets.

The configurations for each node are:

- IP address;
- Default route/default router/gateway;
- Subnet mask and settings;
- DNS settings (server/proxy addresses).

The configurations for each subnet are:

- Default router;
- List of IPs;
- DNS settings;
- Address allocation.

HART Components

The overall system for HART components:

- Both IPv4 and IPv6;
- Compatibility, to work with:
  - Existing software/servers/systems: firewalls, proxy servers, caches, switches, routers and appliances, HAIPEs, gateways, filtering tools/appliances/apps, etc.;
  - Hardware vendors: security and network vendors, including: Cisco, Sun, Microsoft, Check Point, and 3com;
  - Applications: ISR, C2 and targeting (sensors to shooters);
  - Various data types: voice, data, video, sound and security;
- Scalability: 1000's of nodes, across 10's or 100's of subnets and AS's, all mobile and moving;
- Work in red/black networks.

The topology tracker and routing component integrates with the various monitors to track topology and make routing decisions.

- Integrate with monitors;
- IP address assignment, if appropriate;
  - Coordinate across the entire hybrid tactical-AS;
  - IPv4 & IPv6 address spaces;
  - Push address changes to node configuration writers;
- Routing: make dynamic route decisions;
  - Route from 1 subnet type to another (TTNT to Mini-CDL);
  - Leverage commercial router practices that provide a common switching fabric while interchanging line cards operating at different data rates (i.e. T1, DS-3, OC-192);
  - Subnet handoff (node moves from TTNT to QNT, or moves from TTNT and adds mini-CDL, and other use cases);
  - Perform multi-link, multi-channel, multi-antenna multi-path routing and communications topology configurations;
  - Perform static routing (mesh, ring, hub and spoke) between multiple subnets;
  - Perform mobile ad hoc routing between multiple subnets node join/leave, net join/leave;
- Provide a way to provision tunnels/links/flows;
  - Track a link/flow detail record (FDR).

Monitors integrate with the other components to provide network monitoring data:

- Node trackers—SNMP readers (routes, address, location, etc.);
- DNS monitor—(new IP's linked to old names, IP changes for names, red/black concerns, DNS probes, etc.);
- Link quality probes.

Node configuration writers provide the machine-to-machine interface for automatic configuration. It integrates with the other components to provide a single interface to write configuration options and settings to local and remote routers and wireless IP devices. These writer components may use SNMP and/or device specific API's;

- Provide a single option writing API to other components;
- Automatic configuration—HART without human involvement;
  - Local and remote programmatic (API) configuration options to set various IP settings [programmatic control of each radio/device/technology];
  - Use SNMP and/or other protocols/services;
  - May include radio/device specific API requirement.

Dynamic DNS proxy integrates with the other components to track DNS names, changes to DNS entries, and act as a DNS proxy to respond to DNS requests with dynamic responses;

- Integrate with DNS monitors;
- DNS name tracking;
  - HART should act as a proxy for a DNS server;
  - Track DNS name and link to 1 or all IPs for node (each subnet may have a different IP or range);
  - Link Mobile IP “permanent IP” to tactical-AS IP's and DNS name;
- Works in Red/black networks (Black side only, but may be aware of red side effects).

Quality aware proxy monitors the various links and paths connected to HART and across the network, then update the link metrics so that the routers can make smarter decisions:

- Integrate with link quality monitors;
  - Monitors link quality, bandwidth, latency, packet loss, # of retransmits, usage level, available bandwidth (total-used), etc. run these through a formula to produce a “quality metric”;
  - Characterize static link and network performance, bit error rate, packet loss;
- Implement an RFC 5578 proxy;
- Initiate link-quality measuring probes;
- Make/help with routing decisions to optimize based on link quality;
  - Develop, demonstrate and analyze link fade, optical polarization rotation, pointing and tracking, antenna gain, link margins, bit error rates;
  - Update link metrics in local and remote routers and devices.

BGP-MX

HART treats other network integration system as separate ASs. This provides automatic configuration and integration with other networking systems in use

- Integrate seamlessly with BGP routers
- Dynamically discover BGP peers from other as—and setup peering relationships
- Converge new routes rapidly in response to changes in topology
- Integrate with external as—such as:
  - JCAN: Joint Capability for Airborne Networking subnets
  - GIG: Global Information Grid (backhaul/reachback)
  - BACN: Battlefield Airborne Communications Node
  - DISN: Defense Information System Network

The HART addresses at least two major technical challenges to achieve desired capability of an autonomous integration router for tactical edge networks:

- Autonomous Mission Persistent Network Connectivity, i.e. the development of a scalable and automatic approach for establishing and maintaining end-to-end connectivity between user nodes in a dynamically changing tactical network topology with intermittent connectivity to the GIG.
- Autonomous Mission Optimized Network Connectivity, i.e. the development of an enhanced tactical routing approach that is aware of the dynamic changes in the quality of wireless links within the tactical network and that factors link quality into its computation of end-to-end routes to optimize network and mission performance.

Underlying the HART approach for addressing these challenges is a set of techniques that are listed in Table 1 below and described later.

TABLE 1

Technical Challenges	HART Innovations

Autonomous Mission	✓ Hybrid routing with address switching
Persistent Connectivity
Autonomous Mission	✓ Autonomous quality aware routing
Optimized Connectivity

FIG. 5 shows a conceptual view of the HART solution where the integration router contains multiple interfaces, i.e., a LAN interface connected to a HAIPE-fronted platform LAN and WAN interfaces connected to different wireless terminals, e.g., TTNT, QNT, mini-CDL, FSO). Some of these wireless terminals implement bridged IP subnets (e.g., mini-CDL, FSO) while others implement routed IP subnets using proprietary routing protocols (e.g., TTNT, QNT). The software architecture of the HART integration router, shown in Error! Reference source not found., consists of a core OSPF routing function with plug-in router extensions for each type of wireless terminal. The terminal-specific router extensions implement the HART innovations listed above to enable performance-optimized routing across the heterogeneous collections of bridged and routed IP subnets.

The HART approach has two major beneficial features:

- It has no modifications to the software of existing tactical IP radios and optical modems to deliver its network integration and enhanced tactical routing capabilities. This facilitates rapid deployment of the technology in the field by eliminating coordination of software changes with the various vendors of wireless IP terminals.
- It lends itself to a modular implementation architecture where the HART mechanism and techniques are implemented as plug-in software modules that can either be (1) integrated within existing software routers (e.g., quagga, XORP); or (2) executed on add-on processor modules for commercial hardware routers (e.g., within an AXP card for a Cisco router); or (3) integrated within commercially-available programmable high-speed packet processing appliances (e.g., EZ appliance).

In an overview, HART software will provide heterogeneous network integration. The HART approach for addressing these problems will integrate the following innovative techniques into Autonomous Integration Routers:

- Hybrid routing Dynamic Topology and Address Tracking
- Quality-aware link monitoring and routing
- Mobility-enhanced BGP (or BGP-MX)

HART Hybrid routing enables OSPF-based dynamic route discovery and maintenance in a mobile ad hoc airborne network with a diverse set of bridge IP subnets (mini-CDL, FSOC) and routed IP subnets (TTNT, QNT). HART uses OSPF [Boe06, Ci05] between HART nodes and then export routes to (and import routes from) existing routers and radio hardware that may implement proprietary routing protocols. This is in contrast to current solutions that use tunneling of data packets across subnets such as TTNT and thereby incurring excessive network overhead. To eliminate the overhead associated with tunneling data packets across routed IP subnets, such as TTNT, HART will use a novel packet forwarding technique called “address switching” for TTNT, QNT and other tactical routed IP subnets.

To support address switching, HART tracks the names and addresses of node as they join and leave the various subnets. This data is used to track aliases (names or labels) of the nodes in the network as they move. This data forms a topology of the network that HART uses to augment the routing within the network. The topology information is similar to a routing table and is stored as “alias—tag” entries which form the Topology and Address Tracking (TAT) Database. HART uses this alias-tag table along with HART policies to determine routes to use and configuration changes to make on the routers. The policies define link augmentations like replicate data across two or more links to provide for redundancy, or failover priority if links fail or degrade.

In addition to topology data, HART tracks link quality using network monitors, link probes and other techniques. This quality-aware link monitoring is used to calculate a Link Quality Metric (LQM). The LQM is stored in HART and updated in the router on the HART machine adding quality-aware routing to existing routers (which do not have a way to monitor and probe the link quality).

In tactical and airborne networks other domains (groups of subnets) form

ASes (Autonomous Systems). ASes use a protocol called BGP to route between ASes. BGP does not support mobility and dynamic configuration. BGP-MX is a mobility extension for BGP to provide support for mobility and automatic discovery.

The HART Integration Routers are installed on appliances and nodes throughout the black-side (CT side) of a network.FIG. 6 shows the black-side of a notional, multi-subnet airborne network.FIG. 7 shows where HART routers may be installed in the network ofFIG. 6.

HART Routers come in three flavors (shown in Error! Reference source not found.):

- HART-Edge (HART-E): These HART Appliances are installed on each edge node in the network and will route data to and from an endpoint, but not as an intermediate hop in a multi-hop path. These appliances track the local nodes on the platform, and routes and default routers to other networks.
- HART-Interior (HART-I): These HART Appliances are installed on backbone nodes and provide routing to and from nodes. These nodes will use more storage for extensive tables to track nodes. HART-I nodes will forward data about reachability of edge nodes, addresses and status to the HART-Gateway nodes.
- HART-Gateway (HART-G): Same functions as HART-Interior, and also provides links and routes back to the GIG, Internet or other networks. The gateway appliances track the nodes around the network and keep the dynamic address links updated and current.

The HART suite of components is shown in the list below and in Error! Reference source not found. The figure shows the data flow between each of these components. The components are:

- Topology and Address Tracking (TAT)—Dynamic Address Map
- Autonomous Router Configuration (ARC) Module
- Device Configuration Interfaces (DCI)
- HART Policy Editor
- BGP-MX module
- Router

Use case: How HART routes packets

To route data through a network of mixed subnets, HART monitors may track the nodes and build tables of the addresses and how to get from subnet to subnet (Topology and Address Tracking). These tables are called alias-tag tables. The alias-tag table is similar to a routing table, and will be used by HART for routing and address switching. The entries in the alias-tag table contain a destination address (or subnet address), a next hop address (the next hop from the local network to get packets to the final destination address), number of hops, the Link Quality Metric (LQM), and the capacity.

When a network is first set up, HART initializes itself. Then as nodes join or leave, HART updates the alias-tag tables throughout the network. Below is a use case of how this is done.

Initial setup process (FIG. 9):

- HG1 detects GIG and declares “I′m a gateway router”
  - Broadcasts itself as “default route” to GIG.
- HG2 detects GIG and declares “I′m a gateway router”
  - Broadcasts itself as “default route” to GIG.
- HI1 detects no GIG and declares “I′m an Interior router” (default)
  - Receives “default route” from JALN backbone (HG1 and HG2, for specified subnets)
- HI2 detects no GIG and declares “I′m an Interior router” (default)
  - Receives “default route” from JALN backbone (HG1 and HG2, for specified subnets)
  - Becomes “default router” for TTNT radio subnet to link them to GIG (thru JALN backbone)

When a Node Joins the network (Error! Reference source not found.), HART routers monitor and probe the network to test links and configure the alias-tag tables (Error! Reference source not found.) that will be used for address switching later. The process is described below.

Step 1:

- Establish each link from that node to the existing network
- Add alias-tags at various endpoints in the network to enable address switching (faster than routing) (enabled by HART dynamic address and label tracking)

Step 2:

- SatCom connects: Uses fixed SatCom IP to connect to the other SatCom endpoint (12.1.4.8)
- HE1 adds an alias-tag for 17.0.0.0->12.1.4.8
- HG1 adds an alias-tag for 17.1.2.3->12.1.3.1

Step 3:

- First Mini-CDL Radio connects
  - Establishes “link local” addresses on both endpoints
- HE1 adds an alias-tag for 17.0.0.0->224.1.1.1
- HG1 adds an alias-tag for 17.1.2.3->224.1.1.2

Step 4 (FIG. 11):

- Second Mini-CDL Radio connects
  - Establishes “link local” addresses on both endpoints
  - HI1 requests 224.1.1.2 first, but HE1 already is using, so responds with 224.1.1.3
- HE1 adds an alias-tag for 17.0.0.0->224.1.1.1
- HI1 adds an alias-tag for 17.1.2.3->224.1.1.3
- HI1 forwards alias-tag to HG1, HG1 adds it as:17.1.2.3->10.1.2.1 (green arrow inFIG. 11)
- HI1 adds reverse alias-tag

Step 5:

- TTNT Radio connects
  - Uses fixed TTNT IP to connect to the TTNT cloud
  - Finds default router in TTNT cloud (HI2)->sets default router to HI2
- HE1 adds an alias-tag for 17.0.0.0->10.71.103.2
- HI2 adds an alias-tag for 17.1.2.3->10.77.91.1
- HI2 forwards alias-tag to HG1:17.1.2.3->10.2.2.1
- HI2 addsreversealias-tag

The completed alias-tag tables are shown in Error! Reference source not found.

Packet Routing and Rerouting

To route data from H2 (Gnd) to H1 (Air):

Packet leaves H2

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- H2→GIG→HG1

HG1 looks up H1

- Next hop=224.1.1.2(M-CDL): <=1 hop→no address switching
- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HG1→M-CDL→HE1

HE1 receives

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HE1→H1
- SeeFIG. 13

But then an error causes the M-CDL1 link to fail. The flow (H2 (Gnd) to H1 (Air)) is rerouted:

HG1 looks up next path to H1

- Next hop=10.1.2.1(JALN): 2 hop→address switching
- Packet: Src=19.1.2.3; Dst=10.1.2.1; (JALN); Dst’=17.1.2.3; Data
- HG1→JALN→HI1

HI1 looks up H1

- Next hop=224.1.1.3(M-CDL): <=1 hop→no address switching
- Restore packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HG1→M-CDL→HE1

HE1 receives

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HE1→H1
- SeeFIG. 14

HART Router Features

The above use case illustrates the HART functionality to provide dynamic network convergence. To do this HART uses three flavors of the Integration router:

- HART-Edge Routers
- HART-Interior Routers
- HART-Gateway Routers

The HART-Edge Routers have these features:

- Reads and acts on HART Policies.
- Local topology and link quality monitors (SNMP, and other APIs).
- Autonomous device, router and radio configuration (SNMP, and other APIs).
- Forwards data to HART-Interior nodes using (address switching, IP routing, bridging, and repeating).

The HART-Interior Routers, same as HART-E, plus these features:

- Same as HART-Edge Routers.
- Autonomous data switching and routing (address switching, IP routing, bridging, and repeating).
  - Advanced routing/switching to other subnets and hosts.
  - Ability to setup/configure tunnels.
- Regional/Domain monitoring of node availability, topology (next hop, path), names, connection status, and quality (SNMP, and other).
  - Stores this data in an internal table to use for routing/switching data.
  - Shares this data with neighbor HART routers.
- Capable of using OSPF and other generic or “default” routing algorithms (enhanced with link quality metrics).

The HART-Gateway Routers, same as HART-I, plus these features:

- Same as HART-Interior Routers.
- Collects and Tracks IP addresses and next-hop information for nodes on the hybrid network. This data is used to update the dynamic address links so nodes outside the dynamic hybrid network can reach the nodes as they move and shift addresses within the hybrid network.
- BGP and BGP-MX mobility extensions to interconnect (link, route, switch) to external networks (GIG, other Autonomous Systems [ASes]).

HART Architecture Overview

Each of the three flavors of routers is built from the same core components. These components are shown in Error! Reference source not found. and described in further detail below.

HART Monitors

This is the HART Topology and Address Tracking system. The HART monitors are a collection of monitoring and capture tools that gather data about the network, nodes, links, topology, quality, etc. These tools use various methods to collect and gather this data from many sources: SNMP, Radio APIs, network probes, etc. As this data is collected it is stored in two databases. The first stores the majority of monitored data (topology, link quality metrics, etc.) the second is the address map database that stores the alias-tag tables that are used for routing. The address map is constantly maintained and kept small to enable fast routing lookups.

- Node trackers—SNMP readers (routes, address, location, etc.)
- Address and label monitor—(new IP's linked to old/existing names, IP changes for names, red/black concerns, DNS probes, etc.)
- Link quality probes
  - Monitor link quality, bandwidth, latency, packet loss, # of retransmits, usage level, available bandwidth (total-used), etc. These are combined through a formula to determine a Link Quality Metric (LQM)
  - Characterize static link and network performance, bit error rate, packet loss.

As nodes are discovered they will be added to the tracking data by using “Node Join” commands.

Dynamic address mapping and topology tracking module integrates with the monitor and database components to follow dynamic mobile nodes and update the mappings of links to the fixed addresses of edge platforms. This allows GIG connected nodes to find and route traffic to dynamic mobile end points with minimal overhead. This service is also used to track and link DNS names of mobile nodes with alternative IP addresses (maintained by HART) to reach those nodes.

- Integrate with HART monitors
- Store most current data about network status, IP addresses of nodes, link status and link quality
- Track link/flow detail records
- Topology and Address Tracking—Dynamic Address Mapping and name tracking
  - Track a platforms “permanent IP” and DNS names (through different radio subnets)
  - Link “permanent IP” to 1 or all dynamic IPs within the tactical-AS for the node (each radio subnet may have a different IP or range)
  - HART should act as a proxy for a DNS server requests
  - Level and amount of Topology and Address Tracking data stored by HART on a node depends on if the node is a HART-Edge (next hops, default routes), HART-Interior (region or AS based data), or HART-Gateway (GIG scale, multi-AS, very large scale)
- Works in Red/black networks (Black side only, but be aware of red side effects)

Alias Tag Table

Each HART node maintains a table of “alias tags” (address labels or “next hops”) to reach specific end points or subnets. Alias tags are the name of the labels used for the address switching done by HART. These tags are also used as routes to nodes and subnets.

Each minimal entry in the table has a:

- Destination
- Local radio or subnet to use
- Link Quality Metric (LQM)
- Link/route Capacity (or bandwidth)

An alias-tag entry is shown inFIG. 16.

The LQM is calculated based on some combination of number of hops to get to the destination through that radio subnet (H); and expected latency to get to the destination through that radio subnet (L) calculated over some time period. The H, L and capacity values are the minimal values for link quality selection. Other values that may be used include:

- Name (Node name, DNS, etc.)
- Location (lat., long.)
- Other link quality metrics, such as: (ave. packet loss, ave. # of retransmits, bit error rate)

HART-E routers maintain only a limited table of how to connect to the larger network and default routers (or the closest HART-I or HART-G router), the format of this data is shown below inFIG. 17. HART-I and HART-G routers maintain entries that allow cross routing and switching between radio subnets without requiring to route through a GIG node.

(Note: H, L, B will be replaced with LQM and Capacity)

The HART autonomous router configuration (ARC) module uses OSPF and the information from the TAT Database to make routing decisions and to auto configure various aspects of the network and resources. This module is able to send data by routing, address switching, bridging or repeating. It is able to replicate and load balance data across multiple links as well. This module also integrates with existing routers through OSPF, RIP or other standards.

- Integrate with (use) Topology and Address Tracking tables (alias-tags).
- Act autonomously using policies as framework.
- IP address assignment if appropriate
  - Coordinate across the entire hybrid tactical-AS
  - IPv4 & IPv6 address spaces
  - Push address changes to node configuration writers
- Able to send data by address switching, routing, tunneling, bridging or repeating
- Make dynamic data forwarding decisions
  - Implement OSPF between HART nodes
  - Route from 1 subnet type to another (TTNT to Mini-CDL)
  - Leverage commercial router practices (OSPF, RIP or other standards) that provide a common switching fabric while interchanging line cards operating at different data rates (i.e. T1, DS-3, OC-192)
  - Develop and demonstrate static routing (mesh, ring, etc.) between subnets
  - Develop and demonstrate mobile ad hoc routing between multiple subnets node join/leave, net join/leave
  - Subnet handoff (node moves from TTNT to QNT, or moves from TTNT and adds mini-CDL, and other use cases)
  - Replicate (increase reliability) and load balance data (increase throughput) across multiple links.
  - Develop, demonstrate and analyze multi-link, multi-channel, multi-antenna multi-path routing and communications topology configurations
  - Autonomously provision tunnels/links/flows
- Use quality aware extensions
  - Use monitored link quality data to update the link metrics of routing protocols (OSPF, etc.) so routers (non-HART also) can optimize based on link quality
    - Develop, demonstrate and analyze link fade, optical polarization rotation, pointing and tracking, antenna gain, link margins, and bit error rates.
    - Update link metrics in local and remote routers and devices.
- Integrate with existing routers through OSPF, RIP or other standards.

HART routing priority and format

- Is next hop <2 hops?
  - Y: Send direct to next hop.
  - N: Does “next hop” support HART address switching?
    - Y: address switch to next hop.
    - N: Tunnel to next hop.

HART address switched packet format

Original Packet:

Address switched packet (option 1):
NDst—Next hop destination
Dest’—Original destination
Overhead: Adds>=5 bytes—Turn on options, then add the Dest’ address (4 bytes) (More in IPv6)
Address switched packet (option 2):
NDst—Next hop destination
HAS-flag—Some special HART set of IP options to indicate a HART address switched packet OR a specific DSCP value OR an IP Protocol code (or combination of these indicators)
Dest’—Original destination
Overhead: Adds 4 bytes—Length of the Dest’ address (More in IPv6)
NOTE: Where possible HART will learn and save next hops (paths and routes) to be used for a conversation. This will remove the need to include the Dest’ field in every packet, removing the overhead from later packets in the conversation.
HART Tunneling packet format
Original Packet:
Tunneled Packet:
NDst—Address of “Next hop” HART router
HAS-flag—Some special HART set of IP options to indicate a HART tunneled packet OR a specific DSCP value OR an IP Protocol code (or combination of these indicators)
Overhead: Adds at least 40 bytes—full original IP packet is wrapped inside a new IP packet (More in IPv6)
Inter-HART communication commands
Inter-HART communication commands define any HART to HART messages to share data.
Leave/join update message
When a node leaves one subnet or joins a new subnet, the HART routers send an update. This update will be sent on the old subnet after a timeout period. Another update will be sent on the new subnet after a join is completed. These updates will serve the purpose of informing the HART-I and HART-G routers of where edge and interior nodes can be found (after moving), and any new or updated paths to get to those nodes or quality metrics along the paths.

Node Join

- Destination node
- HART-E router for node
- Route (Next hop) (or NULL for endpoint) (this gets filled after the first hop)
- #Hops (increment for each hop)
- Latency
- Bandwidth
- TBD—Other Quality Metrics

Node Leave

- Route/path Drop flag
- Destination node
- HART-E router for node

HART Device Configuration Interfaces

HART device configuration interfaces provide the machine-to-machine interface for automatic configuration. It integrates with the other components to provide a single interface to write configuration options and settings to local and remote routers and wireless IP devices. These writer components may use SNMP and/or device specific APIs.

- Provide a single configuration API to other components
- Automatic configuration—HART without human involvement
  - Local and remote programmatic (API) configuration options to set various IP settings [programmatic control of each radio/device/technology]
  - Use SNMP and/or other protocols/services
  - May include radio/device specific API requirement

Device Configuration commands

Basic IP configuration of devices use (in an embodiment, minimally) the commands described below. HART defines a single, unified API to connect and set these commands for each radio device supported by HART (Mini-CDL radios, SNMP devices, TTNT, etc.).

Set/Get IP Address

- Get/set flag
- Interface to get/set address
- Address
- Subnet Mask
- Default Router

Set/Get Route

- Get/set flag
- # of Route to set (Entry # in a table, 0=default route)
- Destination (address or subnet)
- Route (Next hop)
  Set/Get DNS settings (server/proxy addresses)
- Get/set flag
- Primary DNS Server (or HART DNS Proxy)
- Secondary DNS Server (or HART DNS Proxy)
  Set/Get IP Address Allocation settings (DHCP)
- Get/set flag
- IP range Start address
- IP range Stop address
- Subnet Mask of Range
- Default Router of Range
- Primary DNS Server (or HART DNS Proxy) of Range
- Secondary DNS Server (or HART DNS Proxy) of Range

HART Policy Editor

The HART Policy Configuration GUI allows the user to setup and maintain the policies used by the HART routers. This tool allows the user to define the default link for traffic and the order of backup or failover links to use. Once the default is setup, the user can specify different traffic types based on matching DSCP (differentiated services code point) and/or protocol ID fields. For each traffic type a primary link can be selected and then the other links can be ordered as to which link(s) will be used to failover that traffic type.

A policy option in the HART prototype is multi-link forwarding. For a specified traffic type (specific DSCP and/or protocol ID) multiple links can be specified to replicate packets on. This option sends the same packet or data frame across multiple links to provide improved reliability. If the primary link fails the data will not be lost or interrupted, the flows will continue across the other specified links without affecting the data flow at all.

Policy types:

Default Policy: primary and backup links for all non-specified traffic.
Automatic Failover Policy: primary and backup links for all specific traffic. Specific traffic defined by DSCP and protocol ID fields.
Multi-Link Forwarding Policy: specify primary link and replication links to replicate specific traffic on. Specific traffic defined by DSCP and protocol ID fields.
Load Balancing Policy: specify group of links to spread specific data across (not replicate). Each link will be used in a rotating fashion. Different data packets will be sent simultaneously across several links arriving at the same time. This has the effect of increasing throughput. Specific traffic defined by DSCP and protocol ID fields. Example:
- If DSCP==18 (AF21) then PrimaryLink=Mini-CDL1 and FailoverLink0rder=AN/ARC-210(V); Mini-CDL2; WGS; Inmarsat
- Provide a GUI tool to edit policies
- Write policy files.
- Read existing policy files

Policy Table entry

- Each Policy will have these values:
- DSCP value (or NULL)
- And/or flag (0-AND, 1-OR)
- IP Protocol Code (or NULL, especially if DSCP is NULL)
- Policy Type (0-Default Policy; 1-Automatic Failover Policy; 2-Multi-Link Forwarding Policy; 3-Load Balancing Policy)
- Primary Link Identifier
- Secondary Link Identifier Priority List

BGP-MX Module

HART treats other network integration systems as separate ASes. This provides automatic configuration and integration with other networking systems in use. An extension to BGP is used to add mobility awareness and dynamics.

BGP-MX:

- Integrates seamlessly with BGP routers
- Dynamically discover BGP peers from other as—and setup peering relationships
- Converge new routes rapidly in response to changes in topology
- Integrate with external AS's such as:
  - JCAN: Joint Capability for Airborne Networking subnets
  - GIG: Global Information Grid (backhaul/reachback)
  - BACN: Battlefield Airborne Communications Node
  - DISN: Defense Information System Network

HART Design Details

HART is designed for several real-world use cases of multi-subnet environments with different radio and routing capabilities.

A subset of functionality was selected to create a prototype to demonstrate the HART approach. The features selected for prototyping were proactive failover across many links and integration with a Mini-CDL radio and interface. With the proactive failover mechanism, the HART router monitors the quality of each radio link to detect when it falls below a specified threshold. Upon detection of unacceptable link degradation, the HART router proactively routes all IP packet flows traversing the degraded link to a backup link of higher quality. If or when the original link recovers its quality, the IP packet flows are switched back to this link. Current systems provide no capability for proactive link failover; failover occurs only after a complete breakdown of a link. Application performance suffers as a consequence.

As shown inFIG. 19, the UAV platform has two Mini-CDL radios, an AN/ARC-210(V) radio, an Inmarsat (BGAN) SatCom and a WGS SatCom. The GCS (Ground Control Station) in this case will have the same five endpoint radios. HART in this case exploits the redundant data paths to provide increased reliability of the IP-based connection between the GCS and the UAV. This system does not use HAIPEs to create a red/black network.

In an embodiment, HART consists of two kinds of appliances: the HART-Edge appliance resident on the UAV and the HART-Gateway appliance resident at the GCS.

The HART-Edge Appliance has eight Ethernet ports. Five of these ports are used to connect to the five RF links as shown inFIG. 20. The other three ports are available for use by on-board hosts and sensors on the UAV to connect to the tactical network via the HART-Edge appliance. In this case, each on-board IP device (sensor or CPU) will use the HART router as its “default router”.

Ground Control Station (GCS) Network

There is an Ethernet network (LAN) at the GCS to connect various hosts and servers. This ground network uses a hub or switch to connect all the devices (FIG. 21). The GCS has ground-based transceivers for the various RF/wireless communications devices. Each of these devices has an IP/Ethernet interface.

The HART-Gateway Appliance has eight Ethernet interfaces, one connected to the ground network router and another connected directly to each of the RF/wireless devices (FIG. 21). Optionally, HART could connect to another LAN on the RF side that has the RF/wireless devices connected to a hub or switch.

The GCS may have external networks (i.e. internets) connected to the ground LAN. With proper routing configuration this does not affect HART, and in fact HART will route data to and from the UAV to the external networks as well.

Each RF/wireless radio device used in this scenario is listed above with specifications that are used by HART to make informed policy based routing decisions.

HART Features

- FreeBSD PC (version 7.3)
- Quad NIC (network interface cards)—at least 5 Ethernet connections
- FreeBSD router software
- Maintain IP data flows between the GCS and one or more UAVs connected to the GCS
- Policy based dynamic link selection
  - Provides automatic link multi-level failover and recovery
- Policy based multi-link forwarding (Stretch Goal)
  - Replication provides high reliability communications
- Policy configuration GUI (Stretch Goal)
- Integration with Cubic Mini-CDL radio hardware

An embodiment of the software architecture of HART is shown inFIG. 22.

HART Policy Configuration

HART uses a Policy Configuration file to define the settings used by HART for link failover. This allows the user to define the default link for traffic and the order of backup or failover links to use. Once the default is setup, the user can specify different traffic types based on matching DSCP (differentiated services code point) and/or protocol ID fields. For each traffic type a primary link can be selected and then the other links can be ordered as to which order each will be used to failover that traffic type.

The last policy option in the HART prototype is the multi-link forwarding. For a specified traffic type (specific DSCP and/or protocol ID) multiple links can be specified to replicate packets on. This option will send the same packet or data frame across multiple links to provide improved reliability. If the primary link fails the data will not be lost or interrupted, the flows will continue across the other specified links without affecting the data flow at all.

Three policy types:

- Default Policy: primary and backup links for all non-specified traffic.
- Automatic Failover Policy: primary and backup links for all specific traffic. Specific traffic defined by DSCP and protocol ID fields.
- Multi-Link Forwarding Policy: specify primary link and replication links to replicate specific traffic on. Specific traffic defined by DSCP and protocol ID fields.

Example:

- If DS CP==18 (AF2 1) then PrimaryLink=Mini-CDL1 and FailoverLink0rder=AN/ARC-210(V); Mini-CDL2; WGS; Inmarsat

HART Emulation Testbed

Emulab was used to create a HART testbed (FIG. 23), consisting of:

- Two HART routers running on either end of 5 links (hart0&hart1)
- Two user nodes running various applications on the endpoints (ep1 & ep1)
- Four links emulated by Emulab Delay nodes (D) and Radio Emulators (emul0 & emull)
  - Radio Emulator are adjusted during the experiment to report lesser quality to HART, causing HART to make route adjustments (e.g. failover)

Radio Link Specifications Details

In a live scenario, the wireless radio devices and specifications used are:

- Mini-CDL Radio
  - Bandwidth: 8 Mbps (5.4 Mbps-10.7 Mbps)
  - Latency: 400ms RTT
  - Interface: Ethernet
  - Data routing: Ethernet Bridge: data comes in over Ethernet, then is transferred directly to the paired endpoint
  - Range: LOS: surface-to-surface (sts): ave:4.4 nm II surface-to-air (sta): ave:14.8 nm)
  - WGS (Wideband Global SATCOM) SatCom
  - Bandwidth: >2 Mbps
  - Latency: 710 ms RTT
  - Interface: Ethernet
  - Data routing: IP routed through SatHub
  - Range: BLOS
- Inmarsat (BGAN)
  - Bandwidth: 329 kbps (10 kbps-2 Mbps)
  - Latency: 710 ms RTT
  - Interface: Ethernet
  - Data routing: IP routed through SatHub
  - Range: BLOS
- AN/ARC-210(V) (ARC-210 gen5)
  - Bandwidth: 80 kbps (48.8 Kbps-97.7 Kbps)
  - Latency: 400 ms RTT
  - Interface: Ethernet
  - Data routing: Ethernet Bridge: data comes in over Ethernet, then is transferred directly to the paired endpoint
  - Range: LOS: surface-to-surface: ˜55 nm (31-92 nm); surface-to-air: ˜176 nm (119-264 nm)

In the emulation environment to make the configuration and setup simpler, ATC used these link specifications:


Link	Throughput	Latency

Radio0
	5 Mb	20 ms
Radio1	1Mb	200ms
Radio2
	1 Mb	300ms
Radio3
	1Mb	400 ms

In addition to proactive link selection, HART implements multi-level policy-based failover (1, 2, 3, 4, 5 or more backup links in a prioritized order), a capability that is not supported within COTS routers such as Cisco. For instance, with Cisco routers, if the policy route for an IP flow were to fail it will be routed over the default interface. Unlike HART, secondary and tertiary policy routes cannot be specified with Cisco routers.

FIG. 24 (steps 1-4) shows HART link quality monitoring and proactive link failover.FIG. 24 shows the Emulab experiment: 2 LANs connected by 4 links through HART routers. Each LAN has 3 nodes: an endpoint (ep), a radio emulator node (emul) and a HART router (hart). The radio emulator node runs an application that ATC built to emulate the Mini-CDL radios' link quality API, and allow for manual quality adjustment.Step 1 shows a ping from ep0 to ep1.Step 2 shows the Mini-CDL radio emulator (for RadioLink0) being set from 100% to 60%.

Instep 3, HART detects the new quality metric for RadioLink0 is below threshold of 75%, and then triggers the failover to RadioLink1.Step 4 shows the ping times have increased which shows that RadioLink1 may be used instead of RadioLink0. HART may successfully detect link quality degradation by interfacing with the radio and then change the router on “hart0” to use the failover path of RadioLink1.

HART Radio Integration testbed

HART may be used with two real Mini-CDL radios (FIG. 25aandFIG. 25b). HART is integrated with the radios and then successfully shows to monitor the status of the live radios (through the Mini-CDL API), making correct autonomous failover configuration updates to the routers (HARTO and HART1 inFIG. 25b). The demonstration shows a video stream being sent over the radio link. As the link degrades below a preset threshold, routing fails over to a series of backup links.

HART neighbor discovery service automatically discovers IP one-hop neighbor HART edge and transit routers on a radio subnet. HART transmits periodic subnet multicast of Hello messages by each HART router to enable dynamic neighbor discovery. A neighbor table is maintained by each HART router with subnet-specific address and alias addresses of each neighbor.

Subnet Convergence Function

The subnet convergence function provides a common IP subnet layer interface for the routing function. It enables automatic formation of virtual point-to-point link with each neighboring HART router. It performs monitoring of quality metrics for each virtual link. It implements network level flow control.

Virtual Link Formation & Maintenance

Virtual link formation and maintenance provides cut-through routing for implementing a virtual link. It maintains per-flow state for each IP data flow using a virtual link. It performs IP packet header restoration for data packets received over a virtual link.

Link-Quality Monitoring

Link-Quality monitoring functions implement a passive technique for sensing packet loss rate on virtual link. It implements an active, passive, or hybrid technique for virtual link capacity sensing. It implements an active, passive, or hybrid technique for sensing virtual link latency. It provides a link quality query interface and asynchronous notification mechanism.

Network-level Flow Control

Network-level flow control provides network-level control of the rate at which packets are sent to an attached radio. It implements adaptive per-virtual-link rate control based on dynamic sensing of virtual link. It may augment radio-supported flow control (e.g., RFC 5578).

Traffic Redirection

Traffic redirection implements a mechanism to provide redirection of an IP packet flow to a different next-hop than the current one for load balancing or for traffic-aware routing. Flow redirection is based on source and destination addresses of IP packets.

QoS-Aware Unicast Routing Service

The QoS-aware unicast routing service provides an OSPF-based core routing protocol for unicast routing over inter-router virtual links. It interconnects radio IP subnets into one HART network. It maintains multiple routing metrics per virtual link. It implements multiple routing tables, one per routing metric. It performs link-aware route selection. It performs traffic-aware route selection.

Load Balancing Function

Load balancing function performs distribution of traffic exiting an IP subnet across multiple egress links, if applicable. It performs distribution of traffic entering an IP subnet across multiple ingress links, if applicable.

Dynamic Link Metrics

When a HART router has multiple connections to the HART internetwork, the HART design allows that HART router to dynamically configure the link metrics based on radio link monitoring.

Dynamic Route Selection

When multiple paths are available to route IP traffic through the HART inter-network, the HART design allows the dynamic selection of the path that an IP packet flow will take based on routing metrics.

Radio-aware flow control

The HART design allows for flow control between the HART router and its connected radios.

Mission-Aware Traffic Management

The HART design allows the HART internetwork to be configured with a set of mission-specific parameters that influence dynamic link selection and dynamic route selection for specified traffic classes.

Load Balancing

The HART design allows utilization of multiple communication links when such links exist between elements of the HART internetwork. For example, when multiple links exist between two nodes, as shown inFIG. 26aandFIG. 26b, the HART design allows both links (e.g., link a and link b) to be used in parallel to balance traffic flows transiting between the nodes (e.g., R₁and R₂). Error! Reference source not found.a shows how the data is routed in the absence of load balancing, while Error! Reference source not found.b demonstrates how the data flow is balanced across the available links. By load balancing, more data can ultimately be transferred between the two nodes.

An embodiment in which HART Maximizes Network Performance

(Scenario 1) is illustrated inFIG. 27 in which C sends a data file to X, a CSTAR router senses two links from UAV1 to TOC. HART automatically load balances across both links to gain more bandwidth.

Another embodiment in which HART Maximizes Network Performance (Scenario 2) is illustrated inFIG. 28 in which:

- L sends a data file to X
- H sends a data file to X
- HART senses both traffic flows and chooses 2 independent non-interfering routes from L X and H X
- This improves network throughput and performance

A subnet convergence function is illustrated inFIG. 29 in which HART:

- Provides a common IP subnet layer interface for routing function
- Automatically forms virtual point-to-point links with each neighboring HART router
- Monitors quality metrics for each virtual link
- Provides network-level flow control

A subnet convergence function: virtual link formation & maintenance is illustrated inFIG. 30 andFIG. 31 in which HART:

- Provides a virtual IP 1-hop channel between neighboring HART routers
- Cuts-through routing for implementing virtual link
- Provides maintenance of per-flow state for each IP data flow using virtual link
- Facilitates IP packet header restoration for data packets received over a virtual link

A subnet convergence function: link-quality monitoring is illustrated inFIG. 32 in which HART:

- Measures link quality to support link-aware routing
- Uses a passive technique for sensing packet loss rate on virtual link
- Uses an Active/Passive technique for virtual link capacity sensing
- Uses an Active/Passive technique for sensing virtual link latency
- Provides link quality query interface and asynchronous notification mechanism

Bandwidth/latency monitoring is illustrated inFIG. 33 in which HART:

- Uses existing network data as a probe packet
- Sends probe packets of varying size
- Response time (RTT) is a function of probe size
- Uses existing network data as probe packet

Packet-Loss Sensing

- Packet loss is passively sensed using IP header identification and fragment offset fields that are currently unused
- Each packet is tagged
  - IP identification field contains two octets of the HART routers IP address
  - IP fragment-offset field contains a sequence number
- The receiving HART node decodes the tag
  - Missing sequence numbers are indicative of packet loss
  - A sliding window is utilized to account for out-of-order packets

Packet loss detection is illustrated inFIG. 34 in which:

- Packet loss is computed passively
- Each packet is tagged by HART
  - Sequence number (S) is injected into packet header
  - H+S is the same size as H
- The receiving HART node decodes the tag
  - Packet loss occurs when sequence numbers are missing

Subnet convergence function: flow control is illustrated inFIG. 35 in which:

- To prevent head-of-line blocking of packets within the radio
- Network-level control of the rate at which packets are sent to attached radios
- Adaptive per-virtual-link rate control based on dynamic sensing of virtual link
- May augment radio-supported flow control (e.g., RFC 5578)

Subnet convergence function: flow control is further illustrated inFIG. 36 in which HART:

- Prevents radio buffer overrun and packet loss due to head-of-line blocking
- Sends at rate matched to receiver capability
  - Token-bucket scheme
  - Window-based control

Subnet convergence function: traffic redirection is illustrated inFIG. 37 in which:

- HART provides redirection of an IP packet flow to a different next-hop than the current one for load balancing or for traffic-aware routing
- Flow redirection based source and destination addresses of IP packets

Subnet convergence function: traffic redirection is further illustrated inFIG. 38 in which:

- Transit Router Decision
  - Route Through Default
  - Route Through Alternate
  - Redirect To Alternate

Quality of service (QoS) aware unicast routing service is illustrated inFIG. 39 in which:

- Interconnection of radio IP subnets into one HART network
- OSPF-based core routing protocol for unicast routing over inter-router virtual links
- Maintenance of multiple metrics per virtual link
- Multiple routing tables, one per routing metric
- Link-aware route selection
- Traffic-aware route selection

And inFIG. 40 in which:

- Linux kernel router
- OSPF overlay network of HART routers
- Quagga router control daemons
- Kernel routing tables for each traffic class
  - Latency-sensitive
  - Latency-tolerant
- Use OSPF TOS-specific Link State Advertisements (LSAs)
- Tag traffic with DSCP/TOS fields of IP frame

Mobility-management function is illustrated inFIG. 41 in which:

- a. Enable subnet-hopping of HART endpoints
- b. Automatic detection of current radio subnet
- c. Automatic selection of subnet-specific address for the endpoint
- d. Mobility registry providing mapping between portable address of endpoint and its current subnet-specific address
- e. AODV-based mechanism to enable routing to portable addresses in case the mobility registry is unreachable

AndFIG. 42 in which:

- HART “portable” IP address
- Reachable on any subnet for which it has been configured
- HART routers maintain reachability information about “portable” address to subnet-specific address mapping
- Mobility registry maintains mapping between portable and subnet-specific addresses
- Mobility registry “beacons” its presence using network-wide multicast
- Transit router periodically registers the portable and subnet-specific addresses of nodes resident on any of its subnets
- Transit router consults mobility registry if it does not have a mapping between the portable address and subnet-specific address for a packet it is forwarding
- If the mobility registry is not reachable, the transit router invokes AODV to resolve the portable address of a packet

Load-balancing function is illustrated inFIG. 43 in which:

- Network-optimized data transport
- Distribution of traffic exiting an IP subnet across multiple egress links, if applicable

And inFIG. 44 in which:

- Linux ‘tc’ traffic shaper
- Quagga ‘equal-cost multi-path routing’ feature

Quality of Service (QoS) Overview

- Goal to deliver predictable data services
- Important for providing reliable services that are sensitive to bandwidth, latency and error rate
  - Voice
  - Video
- Defined by a set of parameters that describe service level
  - Bandwidth
  - Buffer usage
  - Delay
  - etc

Quality of Service (QoS) Overview

- HART Black side QoS
  - DiffSery with DSCP translation between domains
- KG-250X can provide Red side QoS
  - Red side service level maps to Black side DSCP
  - End-to-end QoS with HART
- SRS complete, design in progress

Red side QoS Design

- Integrated Services: Flow-based service level guarantees via RSVP
  - Red flow source and destination hosts initiate RSVP exchange
  - All Red side routers, including KG-250X, participates in the RSVP exchange
  - Establishes guaranteed level of service for the flow, or fails
    - Source host can try again for a lower level of service

Test AE (illustrated inFIG. 45) creates redundant paths between subnetworks within the network. One of the paths is impaired to exercise the router's ability to switch to the “better” redundant link.

- Creates redundant paths between subnetworks within the HART network
- One of the paths is impaired to exercise routers' ability to switch to the “better” redundant link

Test AF, illustrated inFIG. 46, simplifies test description by eliminating IP addressing specifics, recreates redundant links and verifies load balancing enabling multicast efficiency.

- Simplifies test description by eliminating IP addressing specifics
- Recreates redundant links
- Verifies load balancing, multicast efficiency

Test AG, illustrated inFIG. 47, is network aware and traffic aware.

Network Aware:

- a. Automatically configured network communication, without manual configuration, between/among networks having differing IP protocols
  - i. Hybrid routing with address switching
  - ii. Multi-cast video feed

Traffic Aware

- a. Choose network route, over a network having a paths with a plurality of intermediate nodes, based, at least in part, on the type of traffic/message
  - i. E.g., file transfer: choose route having a relatively high bandwidth
  - ii. E.g., talk: choose route having relatively low latency
- b. Multiple routing tables based on different metrics
  - i. E.g., Table I: based on bandwidth
  - ii. E.g., Table II: based on latency
- c. IP header marked with type of traffic
  - i. Uses the routing table based on the type of traffic

Pro-active Failover

- a. Autonomous quality aware routing
- b. Switch from existing route to a new route prior to network communication failure
  - i. i.e., before communication is lost
  - ii. built-in fault tolerance
- c. If link (route) quality factor degrades below a [predetermined] threshold, then switch route before communication is lost
  - i. E.g., miss two packets but one packet gets through
- d. Monitor quality of each individual link
- e. Detect and remember packet loss

Load Balancing

- a. Apportions traffic over different routes based on [overall] network load, not just on an individual message
  - i. Helps reduce network clogging
  - ii. May result in a longer route for an individual message or some messages but [overall] network performance improves for all or more users

Appendix A: Target IP Radios, Devices and technologies to integrate Primary integration technologies:

TTNT: Tactical Targeting Network Technology

- IP Support: yes, radios provide IP support externally, and internally route at the lower network and mac layers
- Config API (read): SNMP
- Config API (write):SNMP
- Used for: Waveform developed for JTRS (Joint Tactical Radio System) for airborne networking. Similar to ANW (Airborne Networking Waveform). Used for MIDS (Multi-functional Information Distribution System) data traffic as well as other TCP/IP network traffic

Mini-CDL: Miniature CDL radio

- IP Support: yes, provides point-to-point links, used to create IP bridges
- Config API (read):custom API
- Config API (write):custom API

Used for: Video and data links from mini and micro UAVs and UASes.

- NOTE: CDL waveform is not currently compatible with JTRS radios and cannot be used on them
- Background: Subset of CDL (Common Data Link) radio family, smaller form factor. CDL Family:
- TP-CDL: Team Portable CDL
- TCDL—Tactical Common Data Link. Used for: N-CDL, USQ-123, ATARS, BGPHES, CHBDL, SHARP, TIGDL I/II
- N-CDL: Networked CDL
- TIGDL-II: Tactical Interoperable Ground Data Link II(2)
- MR-TCDL: Multi-Role Tactical CDL [ABE: Auxiliary Bandwidth Efficient; and Discovery]

WiMax: Worldwide Interoperability for Microwave Access

- Config API (read): SNMP
- Config API (write): SNMP
- Used for:as a generic test radio (Similar properties to TTNT)

FSO: Free Space Optical

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for:high bandwidth point-to-point links

JCAN: Joint Capability for Airborne Networking subnets

- Config API (read): BGP (BGP-MX) & SNMP
- Config API (write):BGP (BGP-MX) & SNMP
- Used for:Integrating legacy data links via an airborne gateway node

ORCA: Optical RF Communications Adjunct

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for:Hybrid Optical and RF link (DARPA)

BACN: Battlefield Airborne Communications Node

- Config API (read): BGP (BGP-MX) & SNMP
- Config API (write):BGP (BGP-MX) & SNMP
- Used for:Integrating legacy data links via an airborne gateway

Other integration technologies

ONT: Quint Networking Technology

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for:UASs, munitions

ANW: Airborne Networking Waveform

- Config API (read): assumed SNMP
- Config API (write): assumed SNMP
- Background: Waveform developed for JTRS (Joint Tactical Radio System) for airborne networking. Similar to TTNT (Tactical Targeting Network Technology). Used for MIDS (Multi-functional Information Distribution System) data traffic as well as other TCP/IP network traffic

aADNS: Airborne Automated Digital Network System

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP

ASSDL: Airborne Single Slot Data Link

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP

GBS/TGRS: Global Broadcast Service

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Uses:TGRS: Transportable ground receive suite for GBS

MUOS: Mobile User Objective System

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for: JTRS waveform for SatCom (BLOS)

SRW: Soldier Radio Waveform

- Config API (read): assumed SNMP
- Config. API (write):assumed SNMP
- Used for: JTRS waveform

WNW: Wideband Networking Waveform

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for: JTRS waveform
- Uses: OFDM, BEAM, AJ, LPI/D

CMDL: Compact Multi-band Data Link

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP

SNR: Subnet Relay

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for: ad hoc for maritime RF
- Uses: HFIP (IP over HF [High Frequency—3 to 30 MHz])

TSAT: Transformational Satellite Communications System

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for:Used for: HC3 (2)

HNW: Highband Network Waveform

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for:HNR: Highband Network Radio, and WIN-T Waveform. WIN-T (Warfighter Information Network-Tactical)

NCW: Network-Centric Waveform

- Config API (read): assumed SNMP
- Config API (write):assumed SNMP
- Used for: WIN-T Waveform. WIN-T (Warfighter Information Network-Tactical)

DISN: Defense Information System Network

- Config API (read): BGP (BGP-MX) & SNMP
- Config API (write):BGP (BGP-MX) & SNMP
- Used for:NIPRnet (Non-Classified IP Router Network), SIPRnet (Secret IP Router Network)

Appendix B: Use cases of HART behavior

Use Case 1: Mixed HART Routers (TTNT, SatCom, and Mini-CDL)

Initial setup

Definitions of some terms in the figures:

- HART-Edge Router:No Routing, endpoint node only (little/no storage)
- HART-Interim Router: Routing, maintains tables for routing (to and from), may include storage
- HART-Gateway Router: Routing, Provides links to external and/or non-tactical networks (GIG, Internet, etc.)
- Alias-tag Tables:
  - H: number of hops
  - L: Latency
  - B: Bandwidth
    Initial setup process (FIG. 48):
- HG1 detects GIG and declares “I′m a gateway router”
  - Broadcasts itself as “default route” to GIG.
- HG2 detects GIG and declares “I′m a gateway router”
  - Broadcasts itself as “default route” to GIG.
- HI1 detects no GIG and declares “I′m an Interim router” (default)
  - Receives “default route” from JALN (HG1 and HG2, for specified subnets)
- HI2 detects no GIG and declares “I′m an Interim router” (default)
  - Receives “default route” from JALN (HG1 and HG2, for specified subnets)
  - Becomes “default router” for TTNT radio subnet to link them to GIG (thru JALN)
    Node Joins a Mixed HART network

When a Node Joins (FIG.49)—Step 1:

- Establish each link from that node to the existing network
- Add alias-tags at various endpoints in the network to enable label switching (faster than routing) (This is the HART Dynamic DNS)

Step 2, FIG. 50:

Step 3, FIG. 51:

- First Mini-CDL Radio connects
- Establishes “link local” addresses on both endpoints

Step 4, FIG. 52:

- HE1 adds an alias-tag for 17.0.0.0->224.1.1.1
- HG1 adds an alias-tag for 17.1.2.3->224.1.1.2

Step 5, FIG. 53:

- Second Mini-CDL Radio connects
- Establishes “link local” addresses on both endpoints
- HI1 requests 224.1.1.2 first, but HE1 already is using, so responds with 224.1.1.3

Step 6, FIG. 54:

- HE1 adds an alias-tag for 17.0.0.0->224.1.1.1
- HI1 adds an alias-tag for 17.1.2.3->224.1.1.3

Step 7, FIG. 55:

- HI1 forwards alias-tag to HG1, HG1 adds it as: 17.1.2.3->10.1.2.1
- HI1 adds reverse alias-tag

Step 8, FIG. 56:

- TTNT Radio connects
- Uses fixed TTNT IP to connect to the TTNT cloud
- Finds default router in TTNT cloud (HI2)->sets default router to HI2

Step 9, FIG. 57:

- HE1 adds an alias-tag for 17.0.0.0->10.71.103.2
- HI2 adds an alias-tag for 17.1.2.3->10.77.91.1

Step 10, FIG. 58:

- HI2 forwards alias-tag to HG1: 17.1.2.3->10.2.2.1
- HI2 adds reverse alias-tag
  Completed Table Entries are illustrated inFIG. 59:

Packet Routing, Rerouting and ReturnRouting Step 1 (FIG. 60):

- Packet leaves H2
- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- H2→GIG→HG1

Routing Step 2 (FIG. 61):

- HG1 looks up H1
  - Next hop=224.1.1.2(M-CDL): <=1 hop→no label switching
  - Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
  - HG1→M-CDL→HE1

Routing Step 3 (FIG. 62):

HE1 receives

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HE1→H1
  Error occurs in M-CDL1 link (FIG. 63):

Re-Routing Step 1 (FIG. 64):

HG1 looks up H1

- - Next hop=10.1.2.1(JALN): 2 hop→label switching
  - Packet: Src=19.1.2.3; Dst=10.1.2.1; (JALN); Dst’=17.1.2.3; Data
- HG1→JALN→HI1

Re-Routing Step 2 (FIG. 65):

HI1 looks up H1

- Next hop=224.1.1.3(M-CDL): <=1 hop→no label switching
- Restore packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HG1→M-CDL→HE1

Re-Routing Step 3 (FIG. 66):

HE1 receives

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HE1→H1

Return Path (FIG. 67):

Packet leaves H1

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- H1→HE1

HE1 looks up H2

- Next hop=224.1.1.1(M-CDL2)
  - 2 hop→label switching
- Packet: Src=19.1.2.3; Dst=10.1.2.1; (JALN); Dst’=17.1.2.3; Data
- HE1→M-CDL2→HI1

HI1 looks up H2

- Next hop=10.3.2.1(JALN)
  - <=1 hop→no label switching
- Restore Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HI1 4 JALN→HG1

HG1 receives

- Packet: Src=19.1.2.3; Dst=17.1.2.3; Data
- HG1→GIG→H2
  Use Case 2: Node moves from one TTNT subnet to another TTNT subnet
  Initial setup (FIG. 68):

All nodes start at “I′m an Interim router” (default)

Platforms

1,3 &5 all detect no GIG, so keep: “I′m an Interim router”

- TTNT addresses are fixed, use in name exchanges. . .
- Start exchanging name with other HART routers to build alias tables
  - Platform 1 alias table:
    - To get to “Platform 3” send out local-TTNT to “TTNT-P3”
    - To get to “Platform 2” send out local-TTNT to “TTNT-P2”
  - Platforms 3 and 5 follow similar table entries
- Platforms 2 & 4 detect GIG and change from “interim” to: “I′m a gateway router”
  - GIG found through SatCom
    - Platform 2 becomes TTNT gateway for top TTNT cloud (1,2,3,others) (FIG. B-21)
    - Platform 4 becomes TTNT gateway for bottom TTNT cloud (4,5, others) (FIG. 68)
  - Set Default route entry to:
    - To get to “GIG/Default” send out local-SatCom to “remote-SatCom-Hub”
  - TTNT addresses are fixed, use in name exchanges (include “I′m default router”)
  - Start exchanging name with other HART routers to build alias tables
    - Platform 1 alias table becomes:
    - To get to “Platform 3” send out local-TTNT to “TTNT-P3”
    - To get to “Platform 2” send out local-TTNT to “TTNT-P2”
    - To get to “GIG/Default” send out local-TTNT to “TTNT-P2”
  - Platforms 3 and 5 follow similar table entries
  - Platform 2 alias table:
    - To get to “Platform 3” send out local-TTNT to “TTNT-P3”
    - To get to “Platform 1” send out local-TTNT to “TTNT-P1”
    - To get to “GIG/Default” send out local-SatCom to “remote-SatCom-Hub”
  - Platforms 4 follows similar table entries
  - HART gateways exchange alias tables
    - Platform 2 alias table adds:
      - To get to “Platform 4” send out local-SatCom to “SatCom-P4”
      - To get to “Platform 5” send out local-SatCom to “SatCom-P4”
    - Platform 4 alias table adds:
      - To get to “Platform 1” send out local-SatCom to “SatCom-P2”
      - To get to “Platform 2” send out local-SatCom to “SatCom-P2”
      - To get to “Platform 3” send out local-SatCom to “SatCom-P2”
        Route a Packet fromPlatform 1 to Platform 3 (FIG. 68):
- 1. Packet leaves P1: Src=P1; Dst=P3; Data
  - Send to P1-HART
- 2. @P 1-HART
  - Table lookup, P3 goes thru TTNT to address TTNT-P3
  - Change packet: Src=P1; Dst=TTNT-P3; DstSv=P3;Data—swaps Dst to DstSv and sets next hop to TTNT-P3
  - Goes out TTNT to TTNT-P3
- 3. TTNT-P3 forwards up to local Router (P3-HART)
- 4. @P3-HART: Src=P1; Dst=P3; Data
  —swaps DstSv back to Dst, forwards to P3
- 5. @P3: Src=P1; Dst=P3; Data
  Route a Packet fromPlatform 1 to Platform 5 (FIG. 68):
- 1. Packet leaves P1: Src=P1; Dst=P3; Data
  - Send to P1-HART
- 2. @P1-HART
  - Table lookup, P5 —not found, send to default
  - Default goes thru TTNT to address TTNT-P2
  - Change packet: Src=P1; Dst=TTNT-P2; DstSv=P5;Data
    —swaps Dst to DstSv and sets next hop to TTNT-P2
  - Goes out TTNT to TTNT-P2
- 3. TTNT-P2 forwards up to local Router (P2-HART)
- 4. @P2-HART
  - Table lookup, P5—found, send out SatCom to P4
  - Change packet: Src=P1; Dst=SatCom-P4; DstSv=P5;Data
    —sets Dst to next hop to P4
  - Goes out SatCom to Satcom-P4
- 5. Satcom-P4 forwards up to local Router (P4-HART)
- 6. @P4-HART
  - Table lookup, P5 goes thru TTNT to address TTNT-P5
  - Change packet: Src=P1; Dst=TTNT-P5; DstSv=P5;Data
    —swaps Dst to DstSv and sets next hop to TTNT-P5
  - Goes out TTNT to TTNT-P5
- 7. TTNT-P5 forwards up to local Router (P5-HART)
- 8. @P5-HART: Src=P1; Dst=P5; Data
  —swaps DstSv back to Dst, forwards to P3
- 9. @P5: Src=P1; Dst=P5; Data
  Use Case 3: Routing Data on a HART network
Using Replication and Load Balancing
Steps 1-3 (FIG. 69):
- Data Packet stream leaves FS2
  - Src=17.1.2.12; Dst=19.1.7.11
  - FS2→H1
- H1 looks up policy for data traffic:
  - Load balance across 3 (M-CDL1, M-CDL2, A210)
  - Redundant x2
- H1 sends to H2
  - Src=17.1.2.12; Dst=19.1.7.11
    - Copy 1^stpacket to M-CDL1 and M-CDL2
    - Copy 2^ndpacket to A210 and M-CDL 1
    - Copy 3^rdpacket to M-CDL2 and A210
    - Repeat . . .
  - H1→M-CDL(1,2) & A210→H2
- H2 receives
  - Src=17.1.2.12; Dst=19.1.7.11
  - H2→GCS1
- GCS1 receives
  Link Fault while Routing Data across the HART network

In case of link failure, other links should pick up “slack” and connection will continue as is with no interruption (FIG. 70).

Routing Control Messages across the HART network

Steps 1-4 (FIG. 71):

- Control message Packets leaveFS 1
  - Src=17.1.2.11; Dst=19.1.7.12
  - FS1→H1
- H1 looks up policy (control message traffic):
  - Send all packets across A210
  - Replicate control packets across alternating SatCom links (WGS and Inmarsat).
- H1→sends to H2
  - Src=17.1.2.11; Dst=19.1.7.12
  - Send all packets across A210
  - Copy 1^stpacket to WGS
  - Copy 2^rdpacket to Inmarsat
  - Repeat . . .
- H1→A210/SatCom→H2
- H2 receives
  - Src=17.1.2.11; Dst=19.1.7.12
  - H2→GCS2
- GCS2 receives
  Link Fault while Routing Control Messages across the HART network

In case of link failure, other links should pick up “slack” and the connection will continue as is, with no interruption (FIG. 72).

Glossary

- AN: Airborne Network
- API: Application Programming Interface
- ARC: HARTs Autonomous Router Configuration
- AS(es): Autonomous System(s)—a collection of connected Internet Protocol (IP) routing devices under one common network controller
- AXP: Cisco Application Extension Platform, an add-on card installed in a Cisco router
- BACN: Battlefield Airborne Communications Node
- BGP: Border Gateway Protocol—Protocol used to route between Autonomous Systems
- BGP-MX: Border Gateway Protocol
- COTS: Commercial Off-the-Shelf
- CT: Ciphertext—Black side of red/black network
- DCI: HARTs Device Configuration Interface
- DISN: Defense Information System Network
- DNS: Domain Name Service
- DSCP: DiffSery Code Point
- FSOC: Free Space Optics Communications
- GCS:Ground Control Station
- GIG: Global Information Grid
- GUI: Graphical User Interface
- HAIPE(s): High Assurance Internet Protocol Encryptor—aType 1 encryption device that complies with the National Security Agency's HAIPE IS (High Assurance Internet Protocol Interoperability Specification).
- HART: Hybrid Autonomous Router for Tactical Networks
- HART-E: HART-Edge Router
- HART-G: HART-Gateway Router
- HART-I: HART-Interior Router
- HAS-flag: HART Address Switching flag
- INE: Inline Network Encryptor—broad term for HAIPE-like devices
- IP: Internet Protocol
- JALN: Joint Aerial Layer Network
- JCAN: Joint Capability for Airborne Networking subnets
- LQM: Link Quality Metric
- M-CDL: Mini-CDL
- Mini-CDL: Miniature Common Data Link Radio
- OSPF: Open Shortest Path First (OSPF) is an adaptive routing protocol for Internet Protocol (IP) networks.
- PT: Plaintext—Red side of red/black network
- QNT: Quint Networking Technology (QNT) program is a Defense Advanced Research Projects Agency-led (DARPA) technology program to produce a very small and modular digital communications system for a variety of ground and airborne applications.
- RIP: Routing Information Protocol (RIP) is a distance-vector routing protocol, which employs the hop count as a routing metric.
- SatCom: A Satellite Communication link
- SNMP: Simple Network Management Protocol
- TCP/IP: Transport Control Protocol for Internet Protocol, a collection of protocols for routing data on an IP network.
- TAT:HART Topology and Address Tracking
- TTNT: Tactical Targeting Network Technology
- TRL: Technology Readiness Level
- UAV: Unmanned Aerial Vehicle
- UAS: Unmanned Aircraft Systems
- WNW: Wideband Networking Waveform