Network Traffic Demotion for QoS Protection During Failures
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Solution Overview
Problem
Existing methods fail to maintain Quality of Service (QoS) for voice traffic during network failures in large-scale deployments, as they either require excessive bandwidth for backup paths or accept degradation of all traffic flows, leading to congestion and QoS issues during rapid recovery.
Innovation Solution
A method and apparatus that reroute traffic to a backup path after network failure, marking rerouted traffic for potential dropping to localize QoS degradation, ensuring non-rerouted traffic maintains priority and minimizing congestion impact on unaffected traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid recovery mechanisms are used to reroute traffic quickly after network failure, then recovery speed is improved, but congestion occurs during the transient period before new admission control decisions can be made
Solution Approach 1:
The patent applies preliminary action by pre-establishing backup paths and pre-configuring traffic demotion policies before network failures occur. When a failure happens, the backup path is already ready for immediate activation, and the demotion policy is pre-set to automatically mark rerouted traffic, eliminating the need for delay-based admission control decisions during the transient period.
Solution Approach 2:
The patent introduces traffic demotion as an intermediary mechanism between the fast reroute operation and the congestion problem. This intermediary marks rerouted traffic with specific identifiers that allow network elements to selectively treat this traffic differently during congestion events, mediating between the need for fast recovery and the need to maintain QoS.
2Reliability
If a large amount of capacity is allocated to backup paths to maintain QoS during failures, then QoS protection is improved, but significant bandwidth is consumed that could be used for other purposes
Solution Approach 1:
The patent applies local quality by differentiating treatment based on traffic origin rather than applying uniform protection to all traffic. Only traffic that was rerouted due to failure (identified by specific markers) receives differentiated treatment with lower priority, while other traffic maintains its normal QoS guarantees. This localized approach provides QoS protection where needed without reserving capacity for all traffic globally.
Solution Approach 2:
The patent applies partial action by providing QoS protection only to the extent necessary - specifically to rerouted traffic that caused congestion, rather than protecting all traffic flows. The demotion mechanism provides just enough differentiation to prevent congestion collapse during the transient period, without the excessive capacity reservation that would be required to protect all possible failure scenarios.
3Reliability
If all traffic flows are protected during network failure, then QoS for targeted traffic is improved, but congestion affects both original and rerouted traffic resulting in QoS degradation for all traffic
Solution Approach 1:
The patent applies segmentation by dividing traffic into distinct segments based on their routing history. Traffic that was rerouted during failure is segmented from traffic that continued on original paths. This segmentation is achieved through traffic marking mechanisms that assign different identifiers to rerouted versus non-rerouted traffic, enabling differentiated QoS treatment and preventing congestion from affecting all traffic uniformly.
Solution Approach 2:
The patent extends local quality to differentiate between traffic segments with different risk profiles. Rerouted traffic, which is more susceptible to congestion during the transient period, receives lower priority treatment, while non-rerouted traffic maintains higher priority. This localized differentiation prevents the harmful congestion effect from propagating to all traffic flows.
Data Source
AI summary
A method and apparatus for demoting network traffic are disclosed. In one embodiment, a method includes transmitting traffic associated with a session over a first path, and maintaining state information identifying the first path as a forwarding path for the session. Traffic associated with the session is rerouted from the first path to a second path following a network failure and the rerouted traffic is marked so that at least a portion of the rerouted traffic can be dropped at any point in the network if rerouting causes network congestion.