Predictive Anycast Traffic Shaping via Shadow Network
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Solution Overview
Problem
Anycast networks lack deterministic control over traffic shifting between sites, making it difficult to manage and redirect traffic effectively in response to events such as failures or changes in demand.
Innovation Solution
A predictive Anycast traffic shaping system that uses a secondary shadow Anycast network to mirror and modify Anycast addresses, allowing for controlled and deterministic shifts of traffic and load across sites without affecting the primary network, by tracking and mapping traffic shifts and performance characteristics in a separate address space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Anycast addresses are advertised from multiple PoPs without control mechanisms, then traffic distribution is automatic and simple, but deterministic traffic shifting between sites is not possible
Solution Approach 1:
The system segments traffic control by creating separate BGP route advertisements for different client groups. Each PoP can advertise Anycast addresses to specific client subsets through customized BGP communities, enabling deterministic traffic shifting while maintaining overall system simplicity. This segmentation allows granular control over which clients are routed to which PoP without complex global reconfiguration.
Solution Approach 2:
The system performs preliminary traffic shaping by pre-configuring BGP route advertisements and communities before traffic needs to be shifted. Traffic engineering policies are established in advance, defining how different client groups should be routed to different PoPs. This preliminary configuration enables rapid deterministic traffic shifting when needed, rather than reacting to load conditions in real-time.
2Adaptability or versatility
If BGP advertisements are modified to shift traffic, then traffic can be redirected to different PoPs, but the amount of traffic and destination sites are not deterministically controllable
Solution Approach 1:
The system implements feedback mechanisms through BGP route monitoring and traffic measurement at each PoP. By tracking the amount of traffic received from different client groups and measuring current load conditions, the system can adjust BGP advertisements to achieve precise deterministic traffic shifting. This feedback loop ensures that traffic amounts are controllably directed to specific destination PoPs based on measured network state.
Solution Approach 2:
The system changes BGP advertisement parameters such as AS path prepends, local preference values, and BGP community attributes to precisely control traffic distribution. By adjusting these parameters in a controlled manner, the system can deterministically shift specific amounts of traffic to specific PoPs. Parameter changes enable fine-grained control over traffic engineering without requiring complete rerouting.
3Productivity
If Anycast routing is relinquished to network routers, then routing is automatic and scalable, but deterministic control over traffic shifting is lost
Solution Approach 1:
The system introduces BGP community tags and route advertisement intermediaries between the Anycast architecture and network routers. These intermediaries carry control information that enables deterministic traffic shifting while maintaining automatic routing scalability. The BGP community mechanism acts as an intermediary layer that preserves router-based automatic routing while adding deterministic control capabilities through standardized protocol extensions.
Data Source
AI summary
Gateway devices at different sites of a primary Anycast network provide access to the sites by advertising a first set of Anycast addresses. A secondary shadow Anycast network advertises different second sets of Anycast addresses from the different sites in order to predetermine traffic shifts that occur as a result of changing one or more of the second set of Anycast addresses that are advertised from one or more of the sites. A traffic shifting device may implement a predetermined traffic shift in the primary Anycast network by selecting a particular second set of network addresses that produces a traffic shift at least equal to the predetermined traffic shift, mapping the particular second set of network addresses to a modified first set of addresses, and modifying routing in the primary Anycast network by advertising the modified first set of addresses instead of the first set of addresses.