A method for improving the time performance of AVB traffic in IEEE 802.1 TSN: A dual-path method

Abstract

Recently, Ethernet has emerged as a promising technology of in-vehicle networks. The IEEE 802.1 Audio/Video Bridging (AVB) standard closed on 2011 was developed to allow time-synchronized low latency streaming services through IEEE 802 networks. Recently the IEEE 802.1 Time-Sensitive Networking (TSN) standard is being developed to guarantee timely delivery of the scheduled traffic for delivering important control information in vehicle networks. But, it is inevitable that the time performance of the AVB traffic gets worse in the TSN standard, because the AVB traffic has the lower priority than the priority of the scheduled traffic. Therefore, a dual-path method is proposed for improving the time performance of the AVB traffic. This method uses a redundancy path as an independent path. Whereas a redundancy path is used as a backup path in the TSN standard. It means that traffic classes are divided into two groups and transmitted over their own paths. Three approaches are presented in detail in this paper. First, fast node fail detection is proposed to detect node failure in the dual-path method. This detection approach can also compensate exacerbation in reliability caused by eliminating a backup path. Second, a reservation approach is proposed to distinguish paths and conducting bandwidth reservation for each path by using path computation element (PCE), which is used for configuring paths. Third, a recovery approach is proposed to switch a transmission path when either nodes or link is failed. In addition, scenarios of traffic classification are configured to verify the performance of a dual-path method. All scenario results show that the maximum latency of the AVB traffic in the dual-path method is reduced by 861µs to 1512µs, which corresponds to about 30 to 50% of the total latency. Also all these traffic classification scenarios are analyzed.; Recently, Ethernet has emerged as a promising technology of in-vehicle networks. The IEEE 802.1 Audio/Video Bridging (AVB) standard closed on 2011 was developed to allow time-synchronized low latency streaming services through IEEE 802 networks. Recently the IEEE 802.1 Time-Sensitive Networking (TSN) standard is being developed to guarantee timely delivery of the scheduled traffic for delivering important control information in vehicle networks. But, it is inevitable that the time performance of the AVB traffic gets worse in the TSN standard, because the AVB traffic has the lower priority than the priority of the scheduled traffic. Therefore, a dual-path method is proposed for improving the time performance of the AVB traffic. This method uses a redundancy path as an independent path. Whereas a redundancy path is used as a backup path in the TSN standard. It means that traffic classes are divided into two groups and transmitted over their own paths. Three approaches are presented in detail in this paper. First, fast node fail detection is proposed to detect node failure in the dual-path method. This detection approach can also compensate exacerbation in reliability caused by eliminating a backup path. Second, a reservation approach is proposed to distinguish paths and conducting bandwidth reservation for each path by using path computation element (PCE), which is used for configuring paths. Third, a recovery approach is proposed to switch a transmission path when either nodes or link is failed. In addition, scenarios of traffic classification are configured to verify the performance of a dual-path method. All scenario results show that the maximum latency of the AVB traffic in the dual-path method is reduced by 861µs to 1512µs, which corresponds to about 30 to 50% of the total latency. Also all these traffic classification scenarios are analyzed. |최근에 ethernet은 in-vehicle network에서 유망한 기술로 떠오르고 있다. 2011년에 제정이 완료된 IEEE 802.1 Audio/Video Bridging (AVB) 표준은 멀티미디어 스트림에 대해 높은 수준의 Quality of Service (QoS)를 보장하기 위해 개발되었다. AVB 표준 제정 후, 중요한 제어 정보를 전달하는 scheduled traffic의 빠른 전달을 보장하기 위해 IEEE 802.1 Time-Sensitive Networking (TSN) 표준이 개발되고 있다. 그러나, 멀티미디어 정보를 전달하는 AVB traffic의 우선순위는 scheduled traffic의 우선순위보다 낮기 때문에, TSN 표준에서 AVB traffic의 시간 성능이 나빠질 수 밖에 없다. 따라서, AVB traffic의 시간 성능을 향상시키기 위해 dual-path method를 제안한다. 이 방법은 redundancy path를 독립적인 경로로 사용한다. 반면에, TSN 표준에서 redundancy path는 backup path로 사용된다. 즉, traffic class들이 2개의 그룹으로 나누어지고, 각 그룹이 정해진 하나의 경로로 전송된다. 또한, 세 개의 자세한 처리 방법을 제안한다. 첫째로, dual-path method에서 node나 link의 고장을 감지하기 위한 fast node fail detection을 제안한다. 이 감지 접근법은 dual-path method에서 backup path의 제거로 인한 네트워크의 신뢰성 하락을 보완해줄 수 있다. 둘째로, 경로를 구별하여 각 경로에 대해 대역폭 예약을 수행하는 reservation 접근 방법을 제안한다. TSN 표준과 달리 dual-path method에서는 각 경로에 서로 다른 traffic class가 전송되기 때문에, 대역폭 예약 역시 각각 이루어져야 한다. 따라서, 경로를 구성하는데 사용되는 path computation element (PCE)를 활용하여 각 경로에 따라 대역폭 예약을 진행하는 접근 방법을 제안한다. 셋째로, node나 link의 고장을 감지했을 때, 문제가 발생한 경로로 전송되는 traffic class들의 전송경로를 다른 경로로 바꾸는 recovery mechanism을 제안한다. 또한, dual-path method의 성능을 검증하기 위해 traffic classification 시나리오를 구성한다. 모든 시나리오에서 AVB traffic의 시간 성능이 향상된 것을 확인하였다. AVB traffic의 최대 지연 시간은 861 us에서 1512 us로 감소하였다. 즉, TSN 표준에서의 latency에 비해 약 30%에서 50% 감소한 것이다. 또한, 모든 traffic classification의 장점과 단점을 분석하였다.