Virtual LDP Session Relay Label Mechanism
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Solution Overview
Problem
Existing MPLS protocols face challenges in establishing LDP sessions between nodes that do not have IP reachability, as they require direct IP connectivity for TCP connections, which is not feasible in networks with limited routing information.
Innovation Solution
The implementation of a virtual LDP session mechanism that uses relay nodes to establish a virtual LDP session over existing TCP connections, allowing edge LSRs to treat each other as direct neighbors, even if they are remotely located and lack IP connectivity, by using virtual LDP initialization messages and relay labels to define return paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct IP connectivity is required for LDP session establishment, then TCP connection reliability is improved, but network scalability and adaptability are worsened due to inability to establish sessions between geographically dispersed nodes without routing information
Solution Approach 1:
The patent introduces relay nodes as intermediaries that facilitate LDP session establishment between edge LSRs without direct IP connectivity. The relay nodes forward vInit messages between nodes, enabling session establishment across network domains where traditional direct TCP connections would fail, thus resolving the contradiction between connection reliability and network adaptability
Solution Approach 2:
The patent segments the LDP session establishment process into multiple phases: vInit message transmission through relay nodes, session parameter negotiation, and label mapping exchange. This segmentation allows the protocol to handle complex multi-hop scenarios while maintaining the reliability guarantees of TCP connections for the actual data plane
2Adaptability or versatility
If relay nodes are introduced to enable virtual LDP sessions, then session establishment capability is improved, but message exchange complexity and processing overhead are worsened
Solution Approach 1:
The patent extracts the complexity of multi-hop message routing from the edge LSRs and concentrates it in the relay nodes. Edge LSRs only need to send vInit messages to their directly connected relay nodes, while relay nodes handle the complex task of forwarding messages through multiple hops and managing the virtual session state, thus reducing end-device complexity
3Productivity
If virtual LDP sessions are established over existing TCP connections, then network resource utilization is improved, but security management complexity is worsened due to need to maintain LDP state at edge LSRs
Solution Approach 1:
The patent makes existing TCP connections multi-functional by using them both for control plane communication (vInit messages, label mappings) and data plane traffic. This universal usage improves network resource utilization while the standardized LDP state management mechanisms keep complexity manageable through proven protocol designs
Data Source
AI summary
A receiving node receives a virtual LDP initialization (vInit) message from a first node, where the vInit message comprises a request to establish a vLDP session between a requesting node and a target node. If the receiving node does not own a destination address of the vInit message, the receiving node is determined to be a relay node. The relay node inserts a relay label into the vInit message, where the relay label is an outgoing label that the relay node uses to reach the first node, and forwards the vInit message toward the destination address. If the receiving node owns the destination address, the receiving node is determined to be the target node, which extracts a stack of relay labels from the vInit message. The relay labels are used to define a return path to the requesting node for messages transmitted over the vLDP session.