Upstream Label Allocation for MP2MP LSPs
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Solution Overview
Problem
In Multiprotocol Label Switching (MPLS) networks, particularly in MP2MP LSPs, there is a challenge in efficiently managing label allocation and forwarding states across LSRs connected to multiple LANs, leading to complexities in replicating and forwarding multicast data packets bidirectionally.
Innovation Solution
The solution involves creating and managing Label Information Base (LIB) tables in LSRs, where LSRs generate and exchange label mapping messages to establish forwarding states, including context and forwarding labels, and allocate unique labels for bidirectional LSPs, enabling efficient label swapping and packet replication across LANs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If downstream label allocation is used in MP2MP LSPs, then label management is simplified, but bidirectional forwarding state replication becomes complex across multiple LANs
Solution Approach 1:
The patent segments the label allocation process into two distinct phases: downstream label allocation for simplifying label management, and upstream label allocation for enabling efficient bidirectional forwarding. This segmentation allows each direction to be optimized independently, resolving the contradiction between simplified label management and efficient bidirectional forwarding.
Solution Approach 2:
The patent introduces upstream label allocation as an inversion of the traditional downstream-only approach. By allowing upstream LSRs to allocate labels to downstream LSRs, the system enables efficient bidirectional forwarding state replication while maintaining the simplicity of downstream allocation, thus resolving the technical contradiction.
2Productivity
If upstream label allocation is implemented, then bidirectional forwarding efficiency improves, but label allocation protocol complexity increases
Solution Approach 1:
The patent uses existing MPLS signaling protocols (RSVP-TE, LDP, MPLS-TP) as intermediaries to carry upstream label allocation information. This approach enables efficient bidirectional forwarding without requiring a completely new protocol, thus improving productivity while minimizing the increase in protocol complexity.
Solution Approach 2:
The patent makes the label allocation mechanism universal by enabling it to work in both downstream and upstream directions using the same underlying protocol framework. This multi-functionality allows the system to achieve bidirectional forwarding efficiency without duplicating protocol implementations, thereby limiting the increase in protocol complexity.
Data Source
AI summary
An apparatus or method for upstream label allocation on LANs for multipoint (MP) label switched paths (LSPs). In one embodiment of the method, a first router receives a first incoming labeled data packet, wherein the first incoming labeled data packet comprises a first data packet and one or more first labels. The first router creates a first outgoing labeled data packet, wherein creating the first outgoing labeled data packet includes the step of swapping the one or more first labels of the first incoming labeled data packet with a context label and a forwarding label, wherein the first outgoing labeled data packet comprises the first data packet, the context label, and the forwarding label. Ultimately, the first router transmits the first outgoing labeled data packet to second and third routers via a LAN.