Overview
Mobility management enables mobile devices (Mobile Nodes - MNs) to maintain uninterrupted internet connectivity while moving across different networks without changing their IP addresses. This is achieved through IP mobility protocols that handle seamless handovers between networks.
Mobile IP (IP Mobility)
Mobile IP allows a device to have:
- Home Address (HoA): Permanent IP address in its home network.
- Care-of Address (CoA): Temporary IP address in a foreign network.
How Mobile IP Works
- The MN registers its CoA with the Home Agent (HA).
- The HA intercepts packets destined for the MN’s HoA and tunnels them to the CoA.
- The MN sends replies either directly or via reverse tunneling.
Challenges in Mobile IP
- Triangular Routing (MIPv4): Packets must go through the HA, increasing latency.
- Handover Delay: Registration and binding updates cause interruptions.
Macro Mobility (Inter-Domain Mobility)
Manages movement across different administrative domains (e.g., between ISPs).
1. Mobile IPv6 (MIPv6)
- Enhances IPv6 with built-in mobility support.
- Eliminates triangular routing by allowing direct communication between the MN and Correspondent Node (CN).
- Uses Binding Updates (BU) to inform CNs of the MN’s current location.
2. Fast Mobile IPv6 (FMIPv6)
- Reduces handover latency by:
- Predicting movement (using Layer 2 triggers).
- Pre-configuring a new CoA before disconnection.
- Buffering packets to prevent loss during handover.
Micro Mobility (Intra-Domain Mobility)
Manages movement within the same network domain (e.g., campus, enterprise network).
1. Cellular IP (CIP)
- Uses gateway-based routing and paging caches.
- Soft-state routing: Caches paths for active/idle MNs.
- Semi-soft handover: Temporarily uses both old and new base stations to minimize packet loss.
2. HAWAII (Handoff-Aware Wireless Access Internet Infrastructure)
- Hierarchical routing: Updates paths only along the MN’s route.
- Reduces signaling overhead by avoiding global HA updates.
3. Hierarchical MIPv6 (HMIPv6)
- Introduces a Mobility Anchor Point (MAP) to manage local movements.
- The MN has two addresses:
- Regional CoA (RCoA) – For global routing.
- On-Link CoA (LCoA) – For local routing.
- Reduces binding updates to the HA.
Conclusion
- Mobile IP enables global mobility by maintaining a permanent HoA while using temporary CoAs.
- Macro Mobility (MIPv6/FMIPv6) handles large-scale movements across networks.
- Micro Mobility (CIP/HAWAII/HMIPv6) optimizes local handovers for faster, seamless connectivity.
These protocols ensure that wireless devices stay connected while moving, supporting applications like VoIP, video streaming, and IoT in 5G and Wi-Fi networks.