BIER Header Segmentation for Multicast Flow Accounting
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Solution Overview
Problem
Existing BIER procedures lack the ability to effectively monitor and trace multicast flows in BIER networks due to the absence of per-flow state information in the BIER header, making it difficult for network operators to perform accounting and SLA monitoring.
Innovation Solution
The introduction of an extended BIER header that includes a multi-segment entropy field with a fixed accounting value and an egress timestamp, allowing routers to perform flow accounting and path monitoring without deep packet inspection, and enabling network controllers to trace multicast flow paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the BIER header follows the conventional structure without per-flow state information, then the forwarding efficiency and simplicity are maintained, but the ability to monitor and trace multicast flows for accounting purposes deteriorates
Solution Approach 1:
The patent segments the entropy field into multiple segments: a first segment containing a shortened entropy value for ECMP load balancing, and a second segment containing a fixed accounting value for flow identification. This segmentation allows the BIER header to maintain its compact structure for efficient forwarding while simultaneously carrying per-flow accounting information without requiring deep packet inspection.
2Measurement precision
If per-flow state information is added to the BIER header, then the ability to perform traffic accounting and path monitoring improves, but the header complexity and processing overhead increase
Solution Approach 1:
The patent makes the BIER header self-sufficient by embedding both the shortened entropy value for load balancing and the fixed accounting value for flow identification directly within the header structure. This eliminates the need for separate accounting mechanisms or deep packet inspection, as all necessary information is carried in-band within the header itself.
3Speed
If the entropy field is used solely for ECMP load balancing, then the forwarding functionality is maintained, but the capability for traffic accounting and path tracing deteriorates
Solution Approach 1:
The patent extends the functionality of the entropy field by making it serve dual purposes: the first segment (shortened entropy value) continues to support ECMP load balancing for fast forwarding, while the second segment (fixed accounting value) enables traffic accounting and path monitoring. This multi-functionality allows a single field to satisfy both forwarding performance requirements and accounting information requirements.
Data Source
AI summary
A method is performed at a router configured to perform Bit Index Explicit Replication (BIER) for forwarding of multicast packets in a network. The method includes, upon receiving a multicast packet of a multicast flow, accessing flow mappings in which multicast flows are mapped to fixed accounting values corresponding to the multicast flows. The method further comprises generating a BIER header for the multicast packet by encoding a multi-segment entropy field of the BIER header with (i) a variable entropy value for equal-cost multi-path (ECMP) load balancing, and (ii) a fixed accounting value among the fixed accounting values that is mapped to the multicast flow in the flow mappings. The method also includes encapsulating the multicast packet with the BIER header to produce an encapsulated multicast packet, and forwarding the encapsulated multicast packet.