Service Chaining Next Hops for Scalable Subscriber Policy
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Solution Overview
Problem
Existing service path based chaining approaches face challenges in determining downstream service paths for packets, particularly due to the lack of per-subscriber service policy information on line cards, leading to inefficiencies and scalability issues when handling high packet traffic.
Innovation Solution
The method involves generating Service Chaining Next Hops (SC NHs) with Service Chaining Maps (SC maps) and Hosted Next Hops (NHs) to identify and forward packets based on their IP addresses, allowing for dynamic service application without the need for metadata in packet headers or extensive line card provisioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If service path based chaining is implemented with per-subscriber service policy information on subscriber terminating entities, then service chaining capability is improved, but device complexity and scalability deteriorate due to the need to provision line cards with extensive per-subscriber information
Solution Approach 1:
The patent segments the service chaining functionality by introducing Service Chaining Next Hops (SC NHs) that separate service policy determination from packet forwarding. The SC NHs contain service chaining maps that define service sequences, while line cards only need basic forwarding information, dividing the complex system into manageable components with distinct responsibilities
Solution Approach 2:
The patent introduces Service Chaining Next Hops (SC NHs) as an intermediary data structure between the control plane and data plane. These SC NHs act as mediators that carry service chaining information from the subscriber terminating entity to the line cards, enabling service policy propagation without requiring direct provisioning of per-subscriber information on line cards
2Measurement precision
If downstream packets are forwarded to subscriber terminating entity for service path determination, then service path accuracy is improved, but processing time increases due to double processing at beginning and end of downstream service path
Solution Approach 1:
The patent applies preliminary action by pre-computing and caching service chaining information in Service Chaining Next Hops (SC NHs) at the subscriber terminating entity before packets arrive. When downstream packets are received, the line card can quickly lookup the pre-computed service path information in the SC NHs using the destination IP address, avoiding the need to forward packets back to the subscriber terminating entity for service path determination
Solution Approach 2:
The patent extracts the service path determination function from the packet forwarding path by implementing service chaining information lookup directly at the line card level using SC NHs. This extraction allows the line card to independently determine service paths for downstream packets without involving the subscriber terminating entity in the forwarding decision process
3Ease of operation
If ACL based service chaining is implemented with statically programmed rules on line cards, then service path determination is simplified, but adaptability deteriorates due to difficulty in changing or adding rules dynamically
Solution Approach 1:
The patent implements dynamics by making the service chaining information in SC NHs dynamically updatable. The control plane can modify service chaining maps and SC NH entries without requiring line card reconfiguration, allowing service paths to be dynamically changed based on subscriber subscriptions, traffic patterns, or network conditions while maintaining simple line card operation
4Measurement precision
If per-subscriber service policy information is provisioned on all line cards, then service chaining accuracy is improved, but scalability deteriorates when the number of subscribers is high due to scale-wise prohibitive provisioning requirements
Solution Approach 1:
The patent applies universality by creating Service Chaining Next Hops (SC NHs) as universal data structures that can serve multiple subscribers and service types. Instead of provisioning individual per-subscriber information on each line card, the SC NHs contain service chaining maps that can be applied universally to packets matching specific criteria, enabling one line card to handle service chaining for numerous subscribers efficiently
Data Source
AI summary
Exemplary methods for performing service chaining include generating a plurality of service chaining (SC) next hops (NHs) by, for each SC NH hop, generating a plurality of SC maps, each SC map identifying a chain of one or more service modules, wherein each service module is to apply a corresponding service on a packet. The methods further include generating a plurality of hosted NHs, each hosted NH including forwarding information that causes the packet to be forwarded to a corresponding service module. The methods further include in response to receiving a first packet, identifying a SC NH of the plurality of SC NHs based on an Internet Protocol (IP) address of the first packet, and forwarding the first packet to a service module based on the identified SC NH.