Worst-case flow model of VL for worst-case delay analysis of AFDX

Abstract

Worst-case delay analysis is important for avionics full duplex switched Ethernet (AFDX) standardised as ARINC 664. The flow model of virtual link (VL) in the worst-case delay analysis of AFDX is inaccurate, which depends only on the parameters of VL and ignores the impact from the network, so it makes the worst-case delay analysis of AFDX impractical. A worst-case flow model of VL, which takes the worst impact from the network into account, is proposed to mend the worst-case delay analysis of AFDX. This worst-case flow model of VL is applied in one of the main theoretical approaches for worst-case delay analysis, the network calculus approach. It assists the network calculus approach to get the real upper bound of delay for VL.Introduction: Avionics full duplex switched Ethernet (AFDX) [1] is an upgrade from Ethernet for avionics demand. It is a time-critical network for aerospace applications, and worst-case delay analysis is significant for this network. The way to perform the worst-case delay analysis of AFDX is to calculate the upper bound of delay for virtual link (VL) by theoretical calculation. The main approaches for worst-case delay analysis include the trajectory approach [2], the network calculus approach [3] and so on. The network calculus approach is the most mature one, which was first proposed in [3] and applied to AFDX in [2,4,5].The flow model of VL in the worst-case delay analysis of AFDX is constructed according to the parameters of VL. This flow model ignores the impact from the network, so it cannot represent the worst situation of flow, and the worst-case delay analysis of AFDX cannot be rigorous. To overcome this problem, a worst-case flow model of VL is proposed in this Letter, which takes the worst impact from the network into account. This worst-case flow model of VL is applied to the network calculus approach. With this assistance, the network calculus approach can get the real upper bound of delay for VL.

A delay reliability estimation method for Avionics Full Duplex Switched Ethernet based on stochastic network calculus

“…In AFDX, the deterministic end-to-end transmission is guaranteed by the virtual link (VL) mechanism [23]. VL can be seen as a unidirectional logical channel from one source ES to one or more destinations, which defines a deterministic communication path.…”

“…In the previous study [23], as seen in Fig. 5, a series of frames are transmitted through VL i , and the linear traffic envelope (LTP) is built for the worst-case situation, i.e., transmitting maximum-size frames with the minimum transmission intervals.…”

“…Moreover, Yao [38] and Liu [23] summarized the current AFDX traffic models used to derive deterministic traffic envelopes, and found that the linear expression is the only form. In [17], Jiang summarized that there were two ways to estimate the delay reliability via SNC: (i) randomize the input of SNC, i.e., traffic and service envelope functions; (ii) randomize the sciENcE aNd tEchNology reliability derivation based on deterministic traffic and service envelopes (which are not randomized).…”

TSSDN aviation prospect analysis

“…AFDX network greatly improves the performance of airborne network and greatly improves the degree of information interconnection. At present, research on IMA architecture has been relatively mature [4][5][6] . However, in order to further improve the resource utilization efficiency of avionics system and the degree of resource distribution, researchers proposed the distributed integrated modular avionics architecture DIMA, which separated IO and application processing modules on the basis of decentralized placement of general processing resources to improve resource utilization [7,8] .…”