MVPN Join Request Load Balancing Across EBGP and IBGP Paths
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Solution Overview
Problem
Multicast traffic in virtual private networks (VPNs) faces challenges in load balancing multicast join requests across multiple upstream routers, particularly in scenarios with both EBGP and IBGP paths, which can lead to join loops and disrupt existing traffic flows.
Innovation Solution
The technique involves selecting an upstream router for multicast join requests based on the interface of receipt, total join requests sent, and network address, ensuring that the selection avoids join loops and balances load across EBGP and IBGP paths, using a combination of counter-based and hash-based methods for Next Generation MVPNs and a simple approach for Rosen MVPNs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple upstream routers on different EBGP and IBGP paths are used to forward multicast traffic, then load balancing capability is improved, but join loop risk increases
Solution Approach 1:
The patent segments the upstream router selection process into distinct EBGP and IBGP path handling mechanisms. By separating the decision logic for these two path types and applying different selection criteria to each, the system achieves load balancing across multiple paths while preventing join loops through controlled segmentation of the routing decision process.
Solution Approach 2:
The patent introduces an intermediary selection mechanism that mediates between EBGP and IBGP paths. This intermediary layer evaluates both path types and selects appropriate upstream routers based on predefined criteria, acting as a mediator that coordinates load balancing while preventing circular join requests between different path types.
2Productivity
If upstream router selection changes dynamically based on join requests, then load balancing is improved, but traffic flow disruption increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing selection criteria and preferred path configurations before join requests are processed. The system pre-determines acceptable upstream routers and their associated paths, allowing dynamic load balancing to occur within predefined stable parameters rather than allowing unrestricted changes that would disrupt traffic flows.
Solution Approach 2:
The patent utilizes parameter changes by modifying selection parameters such as path type preference, router capability flags, and load distribution weights rather than fundamentally changing the routing architecture. These parameter adjustments enable load balancing while maintaining stability by operating within established operational parameters.
3Ease of operation
If EBGP and IBGP paths are treated uniformly for join request forwarding, then implementation simplicity is improved, but join loop prevention capability deteriorates
Solution Approach 1:
The patent applies local quality by treating EBGP and IBGP paths differently based on their specific characteristics. Instead of uniform treatment, the system applies path-specific selection criteria and forwarding behaviors to each path type, enabling effective join loop prevention while maintaining relatively simple implementation through localized differentiation rather than complex global management.
Data Source
AI summary
A network device receives a join request on a downstream interface, wherein the join request specifies a source device and multicast group, wherein the network device is positioned within a core network of a multicast virtual private network (MVPN) that transmits multicast traffic between the source device and a plurality of receivers associated with customer sites. The network device selects an upstream router to which to send the join request from among a plurality of upstream routers on paths leading to the source device, so as to avoid creating a join request loop in the core network. At least one of the upstream routers is positioned on an Exterior Border Gateway Protocol (EBGP) path toward the source device, and at least one of the upstream routers is positioned on an Interior BGP (IBGP) path toward the source device. The network device sends the join request to the selected upstream device.