L3 Roaming via Mobility Manager and GRE Tunnels
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Solution Overview
Problem
Current wireless local area networks (WLANs) face challenges in maintaining seamless IP connectivity and application-layer connectivity when wireless client devices roam across different IP subnets, leading to disruptions in services like VoIP and streaming applications, as existing solutions like Mobile IP result in sub-optimal routing and increased latency.
Innovation Solution
A layer 3 (L3) mobility protocol and peer auto-discovery techniques are implemented, allowing wireless client devices to retain their IP address across subnets by establishing a mesh network of peer wireless switches with GRE-over-IP tunnels and secure authentication, ensuring seamless roaming and load balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wireless client devices roam across different IP subnets using traditional routing methods, then network coverage is extended, but IP connectivity and application-layer connectivity are disrupted
Solution Approach 1:
The patent introduces a mobility manager as an intermediary component that maintains IP connectivity during roaming. The mobility manager tracks the location of wireless client devices across subnets and intercepts data packets, rewriting destination IP addresses to route traffic through the current access point rather than the home subnet gateway, thereby maintaining seamless connectivity without requiring changes to the client device
Solution Approach 2:
The patent segments the network into home subnets and foreign subnets, with the mobility manager maintaining separate tracking information for each. When a device roams to a foreign subnet, the mobility manager handles the foreign subnet traffic separately from the home subnet traffic, allowing the device to maintain connectivity to both its home network and the foreign network simultaneously through IP address rewriting and packet interception
2Reliability
If Mobile IP protocol is used to maintain IP connectivity during roaming, then IP address retention is achieved, but routing becomes sub-optimal and latency increases
Solution Approach 1:
Instead of following the traditional Mobile IP approach where the client device maintains a care-of address and uses tunneling protocols like GRE, this patent inverts the approach by having the network infrastructure (mobility manager) perform IP address rewriting on incoming packets. This eliminates the need for complex tunneling and reduces latency by directly routing packets to the current access point without encapsulation and decapsulation overhead
3Reliability
If the home wireless switch replicates and forwards BCMC packets through tunnels to current wireless switches, then broadcast/multicast connectivity is maintained across subnets, but network complexity increases
Solution Approach 1:
The mobility manager performs multiple functions including IP address rewriting, packet interception, location tracking, and BCMC packet replication and forwarding through a unified architecture. This consolidates what would otherwise require separate components for each function into a single multi-functional entity, reducing overall network complexity while maintaining BCMC connectivity across subnets
Data Source
AI summary
In a network comprising a first subnet comprising a first WLAN associated with a home wireless switch a second subnet comprising a second WLAN associated with a first current wireless switch and a third subnet comprising a third WLAN associated with a second current wireless switch, methods are provided for forwarding a Broadcast/Multicast (BCMC) packet generated by a first wireless client device when the first wireless client device roams from the first subnet to the second subnet and a second wireless device roams from the first subnet to the third subnet. Other methods are provided for forwarding a BCMC packet generated by a wired host to a first wireless client device when the first wireless client device roams from the first subnet to the second subnet and to a second wireless device when the second wireless device roams from the first subnet to the third subnet.