Endpoint Re-query Mechanism for Alternate Routing in H.323 Networks
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Solution Overview
Problem
In H.323 and SIP networks, existing methods for routing queries fail to effectively utilize alternate endpoints due to insufficient information in admission confirmation messages and high overhead costs of generating security information, leading to call failures and reduced success rates.
Innovation Solution
A method that involves transmitting an initial admission query, receiving a destination address, and upon call failure, incrementing a counter in a re-query to the gatekeeper with the failure cause, allowing for re-determination and transmission of new routing information, enabling subsequent call attempts with alternate endpoints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gatekeeper provides alternate destination endpoints in the ACF message, then the endpoint can attempt calls with alternate endpoints if the initial attempt fails, but the ACF message cannot carry source or destination information required by different destinations, causing call failures
Solution Approach 1:
The endpoint performs preliminary actions by generating and storing security information and call-specific parameters for each alternate endpoint before actually attempting calls to them. When a call failure occurs, the endpoint can immediately use the pre-generated information without needing to request it again, thus resolving the information loss problem while maintaining adaptability to use alternate endpoints
2Reliability
If the originating endpoint generates security information for each alternate endpoint, then the endpoints can be utilized, but the overhead costs become too expensive compared with the probability of actually employing them
Solution Approach 1:
The endpoint generates security information and call-specific parameters for multiple alternate endpoints in advance (partial excessive action), but only actually uses them when call failures occur. This approach ensures reliability by having the information ready when needed, while the actual overhead cost is amortized over many call attempts, making it economically viable
Solution Approach 2:
Security information and call parameters are generated in advance during the admission phase rather than being generated on-demand during call attempts. This preliminary action reduces the overhead cost during actual call operations while maintaining the ability to reliably use alternate endpoints when needed
3Productivity
If the call attempt to the destination fails, then the call is released by the originating endpoint and the call fails, but no re-query mechanism exists to obtain new routing information for alternate endpoints
Solution Approach 1:
The system implements a feedback mechanism where call failure information is fed back to the gatekeeper through a re-query mechanism. The gatekeeper receives the failure information and responds with new routing information for alternate endpoints, enabling the endpoint to retry calls with different routes, thus improving both call success rate and reliability
Data Source
AI summary
A method for re-querying for routing information is disclosed. The method transmits an initial admission query to a gatekeeper or a request for routing information and receives an admission confirmation or routing information response with a destination address. The method then tries to establish a connection with the destination address. Upon reception of a call failure message including a failure cause, the method, optionally, increments a counter and transmits a re-query to the gatekeeper or other routing entity, and the re-query includes the failure cause and, optionally, a value of the query counter.