Content Object Hash Addressing for CCN Router Table Reduction
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Solution Overview
Problem
In content-centric networks (CCN), replicating content across multiple servers without advertising a common name prefix burdens routers with extensive forwarding table updates, potentially leading to incomplete content delivery due to limited table capacity and increased computation overhead from encapsulation methods.
Innovation Solution
The implementation of a content replication system that creates nameless Content Objects addressed by a Content Object hash (COH) self-certifying name, allowing publishers to host these objects across various servers without shared name prefixes, using a named and signed root Manifest and unsigned non-root Manifests to identify and retrieve nameless Content Objects, enabling efficient routing and reducing computational overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If content is replicated across multiple servers with different name prefixes, then content availability and distribution capability are improved, but router forwarding table complexity and size increase significantly
Solution Approach 1:
The patent introduces an intermediary mechanism (Content Object hash and Manifest structure) that mediates between content objects and routing infrastructure. Instead of requiring routers to know all content name prefixes, the system uses hash-based addressing where routers only need to forward based on hash prefixes, not complete content names. This intermediary layer abstracts the complexity from routers while enabling multi-server content replication.
Solution Approach 2:
The patent changes the addressing parameter from traditional name-based routing to hash-based routing. By transforming content names into hash values (COH), the system alters the routing key parameter, allowing routers to use simplified hash prefix matching instead of maintaining extensive name prefix forwarding tables. This parameter transformation reduces router complexity while preserving content distribution capabilities.
2Ease of operation
If traditional name-based content addressing is used, then content routing is straightforward, but computational overhead increases due to encapsulation and forwarding table lookups
Solution Approach 1:
The patent implements self-service through hash-based addressing where content objects carry their own hash identifiers (COH) that enable direct routing without extensive intermediary lookups. The Manifest structure also enables self-description of content locations, allowing clients to determine content sources without complex router interventions. This self-service approach reduces computational overhead by minimizing active routing decisions.
Solution Approach 2:
The system performs preliminary action by pre-computing and embedding Content Object hashes within content metadata and Manifest structures before distribution. This pre-computation of routing identifiers eliminates the need for complex real-time routing computations, as the hash-based addresses are already prepared and can be directly used for forwarding decisions.
3Measurement precision
If content objects are named with unique identifiers, then content can be precisely identified, but security vulnerabilities increase due to off-path attacks
Solution Approach 1:
The patent converts the potential harm of hash-based addressing (which could enable off-path attacks) into a benefit by implementing cryptographic verification mechanisms. The Manifest structure includes signed declarations about content object locations and properties, allowing clients to verify content authenticity. This transforms the hash-based system from vulnerable to secure by adding verification layers that prevent malicious redirection while maintaining the simplicity of hash-based addressing.
Data Source
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Figure 2B~2C
AI summary
A content replication system can cache nameless Content Object across multiple replica servers in a Content Centric Network (CCN). During operation, a CCN client can obtain a nameless Content Object from one or more content-hosting services by disseminating an Interest for a data collection, and receives a Content Object that includes a manifest for the data collection. The manifest can include Content Object hash (COH) values for a set of other Content Objects of the data collection. The client then determines a name prefix for a content-hosting service that hosts the data collection, and generates another Interest for a Content Object of the data collection. This Interest's name includes the name prefix for the content-hosting service, and also includes a COH value for the respective Content Object. The client disseminates the new Interest over CCN to obtain the respective Content Object of the data collection.