SIP Server Routing Blacklist Segmentation

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Solution Overview

Problem

In telecommunications networks, when all destination addresses for a SIP server are blacklisted, requests are rejected until at least one entry times out, leading to prolonged delays and service disruptions, as existing systems do not efficiently handle routing attempts to unresponsive destinations.

Innovation Solution

Implementing a method that maintains primary and secondary blacklists to differentiate routing attempts, where unresponsive destinations are initially marked on the primary blacklist and potentially retried if they become available, and those consistently unresponsive are moved to a secondary blacklist, allowing for alternative routing procedures to manage requests effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If all destination addresses are blacklisted, then requests are rejected immediately to avoid wasted routing attempts, but this causes prolonged service disruptions and unacceptable call establishment times

Engineering Contradiction:

Improverouting reliabilityVSAvoidcall establishment time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The blacklist is segmented into two distinct lists: a primary blacklist for destinations that are currently unresponsive, and a secondary blacklist for destinations that have been unresponsive multiple times. This segmentation allows the system to differentiate between temporary and persistent failures, enabling more nuanced routing decisions that balance reliability with call establishment time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The blacklist status is made dynamic rather than static. Destinations can move between the primary and secondary blacklists based on their responsiveness. When a destination on the primary blacklist becomes responsive, it is removed from the primary blacklist and added to the secondary blacklist. This dynamic approach allows the system to adapt to changing network conditions while maintaining overall routing reliability.

Inventive Principle:

Principle #15Dynamics

2Productivity

If the system attempts to route requests to blacklisted destinations, then it may discover newly responsive destinations and reduce service disruptions, but this increases the time spent on failed routing attempts

Engineering Contradiction:

Improvecall setup efficiencyVSAvoidrouting attempt time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary actions by maintaining a secondary blacklist that tracks destinations which have been unresponsive in the past. Before attempting routing, the system checks both the primary and secondary blacklists. This preliminary classification allows the system to quickly reject requests to persistently failed destinations while still attempting to route to destinations that may have temporarily failed, thus improving call setup efficiency without excessive time waste.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from routing attempts to dynamically update the blacklist status. When a routing attempt to a blacklisted destination succeeds, the system receives feedback that the destination is now responsive and updates its blacklist status accordingly. This feedback mechanism allows the system to learn from past experiences and improve future routing decisions, balancing productivity with time efficiency.

Inventive Principle:

Principle #23Feedback

3Device complexity

If the system maintains a single blacklist, then the structure is simple and easy to manage, but it cannot differentiate between temporary and persistent routing failures

Engineering Contradiction:

Improveblacklist management complexityVSAvoidrouting strategy flexibility

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The single blacklist is segmented into two distinct lists: a primary blacklist for current failures and a secondary blacklist for historical failures. This segmentation provides the adaptability needed to implement different routing strategies based on failure patterns, while the overall structure remains manageable through automated transition rules between the two lists.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the blacklist system serve different purposes with different qualities. The primary blacklist provides immediate rejection for currently unresponsive destinations, while the secondary blacklist provides historical context for persistent failure patterns. Each part has its own specific function and management rules, allowing the system to be versatile in its routing decisions while maintaining manageable complexity through clear local responsibilities.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9716655B2Processing requests

Publication Date: 2017.07.25 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

Measures for processing requests in a telecommunications network are provided. A blacklist for determining routing attempts to be conducted during a default routing attempt procedure is maintained. A request comprising an identifier for a given destination for the request is received and, in response to performing a destination address lookup for the identifier, a set of one or more destination addresses for routing the request to is received. One or more destination addresses in the set are compared to the list of destinations on the blacklist. If the comparison indicates that at least one of the destination addresses in the set is not present on the blacklist, the request is processed according to a default routing attempt procedure. If the comparison indicates that all of the destination addresses in the set are present on the blacklist, the request is processed according to an alternative routing attempt procedure.