Appendix B. Future Extensions
This appendix discusses potential future extensions to the Neighbor Discovery protocol. These are areas where the protocol could be enhanced or extended to address new requirements or improve functionality.
B.1. Additional Router Advertisement Information
Future extensions might include additional information in Router Advertisements:
Enhanced Prefix Information:
- More detailed prefix attributes
- Prefix stability indicators
- Prefix origin information
- Quality of Service (QoS) parameters per prefix
Network Characteristics:
- Bandwidth availability
- Network congestion indicators
- Cost metrics for different paths
- Network type information (e.g., cellular, Wi-Fi, wired)
Service Discovery:
- Information about available network services
- Service location and access methods
- Application-specific network parameters
B.2. Enhanced Neighbor Unreachability Detection
Improvements to Neighbor Unreachability Detection could include:
Adaptive Timers:
- Dynamically adjust timers based on link characteristics
- Different timer values for different neighbor types
- Faster detection for critical neighbors
Bidirectional Reachability:
- Enhanced mechanisms for confirming bidirectional reachability
- Asymmetric link detection and handling
- Reachability correlation across multiple interfaces
Proactive Monitoring:
- Background reachability probes
- Predictive failure detection
- Health monitoring for critical paths
B.3. Improved Security Mechanisms
Security enhancements beyond SEND could include:
Lightweight Authentication:
- Less computationally intensive alternatives to SEND
- Symmetric key-based authentication mechanisms
- Trust-on-first-use (TOFU) approaches
Replay Protection:
- Enhanced timestamp mechanisms
- Nonce-based replay prevention
- Sequence number coordination
Authorization:
- Fine-grained authorization for different ND operations
- Role-based access control for network resources
- Dynamic authorization based on network conditions
B.4. Mobility and Handover Optimization
Extensions to support better mobility:
Fast Handover:
- Pre-configuration of next-hop routers
- Predictive Router Advertisements
- Seamless layer-2/layer-3 handover coordination
Mobile Network Support:
- Better support for mobile networks (e.g., vehicles)
- Dynamic topology adaptation
- Route optimization for mobile scenarios
Multi-Path Support:
- Simultaneous use of multiple paths
- Path quality monitoring and selection
- Load balancing across interfaces
B.5. Energy Efficiency
Extensions for low-power scenarios:
Reduced Signaling:
- Longer Router Advertisement intervals for stable networks
- Suppression of unnecessary Neighbor Discovery messages
- Wake-up scheduling for sleeping nodes
Proxy Mechanisms:
- Enhanced ND Proxy capabilities
- Aggregated Neighbor Discovery for IoT networks
- Battery-aware protocol operation
B.6. Scalability Improvements
Enhancements for large-scale deployments:
Hierarchical Addressing:
- Support for hierarchical neighbor organization
- Scalable multicast group management
- Efficient address resolution in large subnets
Caching Strategies:
- Distributed caching mechanisms
- Cache synchronization across routers
- Predictive caching based on traffic patterns
Aggregation:
- Prefix aggregation announcements
- Neighbor information summarization
- Efficient updates for large address ranges
B.7. Quality of Service Integration
QoS-related extensions:
Traffic Classification:
- Include traffic class information in ND messages
- Per-flow QoS parameters
- Priority-based neighbor selection
Resource Reservation:
- Integrate with resource reservation protocols
- Bandwidth announcement and negotiation
- Admission control coordination
B.8. IPv6-IPv4 Coexistence
Better support for transition scenarios:
Dual-Stack Coordination:
- Coordinated IPv4/IPv6 address management
- Unified reachability detection
- Translation information distribution
464XLAT and MAP Support:
- Distribution of translation parameters
- MAP-E/MAP-T configuration via RA
- Prefix mapping information
B.9. Application-Specific Extensions
Extensions tailored to specific applications:
Real-Time Communications:
- Latency and jitter information
- Path characteristics for RTC
- Symmetric NAT detection and handling
Industrial IoT:
- Deterministic networking support
- Time-sensitive networking (TSN) parameters
- Reliability and redundancy information
Data Center Networking:
- Load balancer discovery
- Fabric topology information
- Fast convergence mechanisms
B.10. Management and Diagnostics
Operational improvements:
Enhanced Diagnostics:
- Built-in troubleshooting tools
- Path MTU discovery improvements
- Reachability testing mechanisms
Configuration Management:
- Automated configuration distribution
- Policy-based ND parameter management
- Centralized vs. distributed control options
Monitoring and Telemetry:
- ND event logging and reporting
- Performance metrics collection
- Anomaly detection support
B.11. Standardization Considerations
When proposing future extensions, consider:
- Backward Compatibility: Ensure new features work with existing implementations
- Incremental Deployment: Allow gradual adoption without disrupting networks
- Security: Address security implications from the start
- Overhead: Minimize protocol overhead and complexity
- Interoperability: Ensure multi-vendor interoperability
- Use Cases: Base extensions on real operational needs
B.12. Research Directions
Areas for further research:
- Machine learning for neighbor behavior prediction
- Blockchain-based trust mechanisms
- Software-defined networking (SDN) integration
- Intent-based networking with ND
- Cross-layer optimization techniques
Note: These are potential future extensions and are not part of the current RFC 4861 specification. Any actual extensions would need to go through the IETF standardization process.