CN115412513A - ARINC664 network receiving terminal time integrity verification method - Google Patents
ARINC664 network receiving terminal time integrity verification method Download PDFInfo
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Abstract
The invention belongs to the technical field of ARINC664 network high integrity design, and discloses a method for verifying the time integrity of an ARINC664 network receiving terminal, which comprises the following steps: s1, acquiring the time DTS when the first byte of the message leaves the sending terminal; s2, calculating a time deviation TOS between the sending terminal and the receiving terminal; s3, obtaining a delay upper bound T _ worst of the message in the switch network; s4, if a receiving end clock when the first byte of the message reaches the receiving terminal is within an upper bound of DTS + TOS + T _ worst, the time integrity check of the message is considered to be passed; and when the receiving end clock exceeds the upper bound of the DTS + TOS + T _ worst, the receiving terminal considers that the time integrity check of the message fails and discards the message.
Description
Technical Field
The invention belongs to the technical field of ARINC664 network high integrity design, and particularly relates to a method for verifying the time integrity of an ARINC664 network receiving terminal.
Background
In the data communication process based on the transmission layer service mechanism in the airplane data network, any data transmission error will have serious consequences on the upper layer application, so that a message receiving end in the data transmission process cannot wait for a message indefinitely, and after waiting for a certain time, if the message is not received, the message should not be received any more, so that the message is ensured to be received within the effective delay time range, and the process is called time integrity check. Because the terminals in the a664 network are all asynchronous terminals and all have respective clock sources, the clock offset between the sending terminal and the receiving terminal must be calculated, so it is necessary to define a clock offset calculation method between the source terminal and the destination terminal and complete message time integrity verification.
Disclosure of Invention
The technical scheme of the invention aims at the problems in the background art and provides a method for verifying the time integrity of a receiving terminal of an ARINC664 network, which ensures the time integrity of a message during transmission in the network.
In order to achieve the purpose, the invention adopts the following technical scheme to realize.
An ARINC664 network receiving terminal time integrity checking method, the method includes:
s1, acquiring a DTS (delay tolerant service) of the time when a first byte of a message leaves a sending terminal;
s2, calculating a time deviation TOS between the sending terminal and the receiving terminal;
s3, obtaining a delay upper bound T _ worst of the message in the switch network;
s4, if a receiving end clock when the first byte of the message reaches the receiving terminal is within an upper bound of DTS + TOS + T _ worst, the time integrity check of the message is considered to be passed; and when the receiving end clock exceeds the upper bound of the DTS + TOS + T _ worst, the time integrity check of the message is considered to be failed, and the receiving terminal discards the message.
The technical scheme of the invention has the characteristics and further improvements that:
(1) S1 specifically comprises the following steps:
and obtaining the data DTS by means of time stamping at the moment that the first byte of the message leaves the sending terminal.
(2) S2, when calculating the time deviation TOS between the sending terminal and the receiving terminal:
s21, firstly, residing an application software on a general processing module GPM in the ARINC664 network for constructing and sending a time request message, and using the general processing module GPM as a time Server;
s22, setting other devices capable of carrying out network communication in the ARINC664 network as time Client terminals, wherein each time Client terminal is resident with application software and is responsible for constructing a time response message and sending the time response message to a time Server;
s23, defining the time Server to stamp the message at the moment when the first byte of the message leaves the sending terminal, and the time Client to stamp the message at the moment when the first byte of the time request message is received;
s24, then the Client constructs a time response message, records the values of the two timestamps of the timestamp in the time response message, and sends the time response message to the Server of the time Server;
s25, after receiving the time response message, the time Server constructs a time stamp list message, puts the time stamp data collected from each time Client into the time stamp list message, then sends the time stamp list message to each time Client, and finally carries out time deviation calculation on the time Client.
(3) In S2, a terminal connected with the time recording server serves as a sending terminal, and a terminal connected with the time clients Client1 and Client2 serves as a receiving terminal;
the time deviation among the local clocks of the time Server, the first time Client1 and the second time Client2 is assumed to satisfy the following relation:
the time of the first time Client1 is delta 1 faster than the time of the time Server; the time of the second time Client terminal Client2 is delta 2 faster than the time of the time Server terminal Server; and the time of the first time Client1 is faster than the time of the second time Client2, the time offset TOS = Δ 1- Δ 2 between the first time Client1 and the second time Client2.
(4) D1 represents the switch network path delay from the time Server to the first time Client1, and D3 represents the switch network path delay from the time Server to the second time Client 2;
the time Server sends a time request message to a first time Client1, a time stamp is marked on the message when a first byte of the time request message leaves, the time request message is marked as T1, and the first time Client1 stamps the message at the moment of receiving the first byte of the time request message, and the time request message is marked as T2;
the time Server sends a time request message to a second time Client2, and stamps a time stamp on the message when a first byte of the time request message leaves, which is recorded as T1', and the second time Client2 stamps the message at the moment of receiving the first byte of the time request message, which is recorded as T2';
then:
therefore, the time offset between the first time Client1 and the second time Client2 is:
TOS＝Δ1-Δ2
＝T2-T1-D1-(T2'-T1'-D3)
＝T2-T1-(T2'-T1')-D1+D3
(5) The maximum value of TOS is:
TOS max ＝T2-T1-(T2'-T1')-SC1delay min +SC2delay max
wherein, SC1delay min Represents the minimum delay of the switch network from the time Server to the first time Client1, SC2delay max Represents the maximum delay of the switch network from the time Server to the second time Client2.
(6) The ARINC664 switch network consists of a plurality of switches; s3, obtaining a delay upper bound T _ worst of the message in the switch network, specifically:
s31, determining the maximum time interval from the time when the first byte of the data frame reaches the input port of a certain switch to the time when the last byte of the data frame reaches the input port of the switch, and recording as L1;
s32, determining the time interval from the time when the last byte of the data frame arrives at the input port of the switch to the time when the first byte of the data frame arrives at the public buffer zone of the switch, and recording as L2;
s33, determining the maximum delay of the data frame at the output port of the switch, and marking as L3;
s34, calculating the maximum delay of the data frame in the switch according to the sum of the L1, the L2 and the L3;
s35, determining the delay upper bound of the data frame in the ARINC664 switch network according to the number of switches contained in the ARINC664 switch network and the maximum delay of the data frame in each switch.
(7) The virtual link defines a logical one-way connection, from a source terminal to one or more target terminals, there are as many VL paths as there are target terminals in a virtual link, and from the source terminal to a target terminal, there is considered as one VL Path;
in S31:
wherein, VL i Representing the ith virtual link and the node representing a certain output port of the switch, called switch node, VL i E node represents the set of virtual links passing through the switch node,
is the maximum frame length allowed by the ith virtual link, C i Is the bandwidth of the ith virtual link at its input port;
in S32: the value of L2 is the maximum jitter time configured by the switch.
(8) In S33, the specific process of calculating L3 is as follows:
(a) Calculating an arrival curve for each VLPath, one hop representing an exit from one device to the next;
the single virtual link arrival curve is represented as: α (t) = σ + ρ t
Wherein, σ is the maximum flow which can be reached in the burst flow, and ρ is the slope upper limit of the flow increase;
(b) Calculating a service curve for each switch, the service curve comprising: service curve beta for high priority data frames h (t) service curve β for low priority data frames l (t)；
β h (t)＝R[t-T] + ,R＝C,
β l (t)＝R[t-T] + ,
Wherein, [ T-T ]] + Indicates that when T-T is greater than zero, [ T-T] + Is equal to T-T, when T-T is less than or equal to zero, [ T-T] + Is equal to zero and is,
is the maximum of the maximum frame lengths of all low priority virtual links output from the same node,
bandwidth for all high priority virtual links through the nodeThe sum of the total weight of the two components,
is the sum of the burst data amounts, T, of all high priority virtual links passing through the node tech Is the technical delay of the switch, and C is the bandwidth of the output port of the switch;
(c) Determining an aggregate arrival curve alpha for all virtual links in a single input port through the same output port SL (t)；
Where SL represents all virtual links through a switch input port of the same switch node, and i ∈ SL represents the virtual link VL through that input port i ；
The inflection point e of the polymerization curve is represented as:
wherein σ i Is the ith virtual link VL i Burst traffic through the input port; rho i Is the ith virtual link VL i The bandwidth of (d); c is the rate of the input port;
(d) Sorting inflexions of the arrival curve of all N input ports passing through the same output port in ascending order by using a grouping technique, wherein the sorted inflexions are marked as E g (g =1,2,. N), N being the number of switch ports; aggregating the input port aggregated data flow after the ascending sorting of the packets at the switch node to obtain an arrival curve at the switch node;
the maximum horizontal delay D caused by queuing competition of data flows at the switch nodes can be obtained by calculating the maximum horizontal distance between the arrival curve and the service curve of the switch nodes max Is marked as T 3 。
(9) (a) calculating an arrival curve of each VLPath, specifically:
(a1) The first hop arrival curve for each VLPath:
wherein S is max Representing the maximum frame length allowed by the virtual link, BAG being the minimum frame interval of the intrinsic parameters of the virtual link, max _ Jitter representing the maximum Jitter time on the virtual link, and max _ Jitter being Jitter in the first hop switch ES Indicating the jitter of the virtual link already existing in the source terminal;
starting from the second jump, using the formula obtained in the following step as an arrival curve of the virtual link;
(a2) Calculate the arrival curve for the next hop of VLPath:
wherein, the first and the second end of the pipe are connected with each other,
is the maximum latency of the aggregate arrival curve in the node,
(10) Maximum horizontal delay D max The calculation process of (2) is as follows:
has an inflection point E x At E x On the left side of (E), the slope of the arrival curve of the switch is greater than or equal to the slope of the service curve, at E x On the right side of (2), the slope of the arrival curve of the switch is less than the slope of the service curve;
when t = E x Then, the maximum horizontal distance D of the arrival curve and the service curve of the switch node is obtained max As the maximum delay of a data frame at the output port of the switch:
wherein T and R are parameters of a service curve of the switch; the intermediate parameter y is calculated according to the following equation:
in the formula (I), the compound is shown in the specification,
m 1 is the number of 10Mbps ports in the switch, m 2 Is the number of 100Mbps ports in the switch, m 1 +m 2 ＝N-s+1，m 2 First, as s increases by 1, when m decreases by 1 2 After decreasing to 0, m 1 Begin to decrease by 1, C as s increases by 1 1 Is 10Mbps 2 Is 100Mbps 0 ＝E 0 ＝0。
(11) First calculatingThe maximum delay of VL Path in a switch, the maximum delay of the switch through which VLi passes, should be calculated according to the following equation:
wherein the content of the first and second substances,
representing the maximum delay for VLi to pass switch j.
(12) The upper end-to-end delay limit of a VL Path in a switch network is equal to the sum of the maximum delays of all switches passed by the VL Path:
wherein, SW j ∈PATH i Indicates the ith VLPATH i A set of switches that pass through;
indicates the ith VLPATH i Maximum delay through jth switch.
The invention defines the time management function and designs the ARINC664 network receiving terminal time integrity checking method, so that the message is received in a reasonable delay range, certain data transmission errors are avoided, and the time integrity of the ARINC664 network terminal is ensured.
Drawings
FIG. 1 is a schematic diagram of a time management function provided in an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating an interaction process between a time server and a time client according to an embodiment of the present invention;
fig. 3 is a schematic time line diagram of a time server and a time client according to an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating an arrival curve of a virtual link at an output port of a terminal system according to an embodiment of the present invention;
FIG. 5 is a schematic view of the arrival curve of a polymerization stream passing through the same inlet provided by an embodiment of the present invention;
FIG. 6 is a schematic diagram of an aggregate flow inflection point ordering provided by an embodiment of the present invention;
FIG. 7 is a schematic diagram of an arrival curve after a grouping technique is used according to an embodiment of the present invention;
FIG. 8 is a drawing providing example E of the present invention x A delay calculation schematic diagram when the time is more than or equal to T;
FIG. 9 is a drawing providing example E of the present invention x <Delay calculation at T is shown schematically.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The invention defines a rule for ensuring the time integrity of a receiving terminal in the process of end-to-end data transmission of an A664 network: if a receiving end clock when a first byte of the message reaches a receiving terminal is within an upper bound of DTS + TOS + T _ worst, the time integrity check of the message is considered to be passed; and when the receiving end clock exceeds the upper bound of the DTS + TOS + T _ worst, the receiving terminal considers that the time integrity check of the message fails and discards the message. Wherein: DTS indicates the time when the first byte of the message leaves the sending terminal, and the data may be obtained by means of stamping a timestamp at the time when the first byte of the message leaves the sending terminal, T _ worst indicates the upper bound of the delay of the message in the switch network, and T _ worst indicates the maximum delay of the switch network that the non-time management message passes from the sending end to the receiving end when performing time integrity check, where the calculation method will be described below. The time request message, the time response message and the time stamp list message are collectively called a time management message, and the time request message and the time response message are single frame data.
To calculate the clock skew TOS, the present invention first constructs a network time management function, as shown in FIG. 1, first resides an application software on a general purpose processing module (GPM) in the A664 networkThe GPM is used as a time Server (Server), and other devices capable of performing network communication in the a664 network are all set as time clients (clients), and each time Client is resident with an application software and is responsible for constructing and sending a time response message to the time Server. Defining the time when the first byte of the message leaves the sending terminal, the server side stamps the message and records it as T 1 The time client stamps the time request message at the moment of receiving the first byte of the message, denoted T 2 The time client then constructs a time response message and sends a timestamp T 1 、T 2 The time server side receives the time response message, constructs a time stamp list message, and collects the time stamp T from each time client side 1 、 T 2 The data is put into a time stamp list message (such as Client1T1, client1T2, client2T1, client2T2, client3T1, client3T2; 8230), and then the time stamp list message is sent to each time Client, and finally the time Client executes the time deviation calculation function.
The specific calculation process of the clock skew in the present invention is described below.
The time deviation among the local clocks of the Server, the Client1 and the Client2 is assumed to satisfy the following relation: the time of the Client1 is faster than the time of the Server, namely, the timing value is larger than delta 1; the time of the Client2 is faster than the time of the Server, namely, the timing value is larger than delta 2; and Client1 is faster than Client2. (and similarly derived in other cases) the time offset between Client1 and Client2 is TOS = Δ 1- Δ 2. As shown in fig. 3, assuming that Δ 1 is a length from point E to point B, point a is a time of T1, point C is a time of T2, and point D is a time corresponding to the time client when the time client stamps T2, that is, a path delay is a length from point a to point D and also a length from point B to point C, as shown in fig. 2, point D1 represents a path delay from the server to the client1, and point D3 represents a path delay from the server to the client2, it can be obtained:
the time offset between Client1 and Client2 is therefore:
TOS＝Δ1-Δ2
＝T2-T1-D1-(T2'-T1'-D3)
＝T2-T1-(T2'-T1')-D1+D3 (2)
neither D1 nor D3 in the formula can be accurately measured, and because the path delay caused by the propagation of the frame in the switch network after the a664 network topology and the network routing of the frame are determined may be the maximum delay (arranged at the end of the queue) or the minimum delay (arranged at the front of the queue), if the time integrity check of the receiving terminal is more reasonable, that is, when it is more reasonable to consider when the receiving terminal no longer waits for the message, D3 in the time deviation calculation formula is amplified to the maximum delay of the switch network passing from the Server to the Client2, and D1 is reduced to the minimum delay of the switch network passing from the Server to the Client 1.
If a receiving end clock when the first byte of the defined message reaches a receiving terminal is within an upper bound of DTS + TOS + T _ worst, the time integrity check of the message is considered to be passed; and when the receiving end clock exceeds the upper bound of the DTS + TOS + T _ worst, the time integrity check of the message is considered to be failed, and the receiving terminal discards the message. Considering the upper bound TOS of calculating TOS at this time max The calculation formula is as follows:
TOS max ＝T2-T1-(T2'-T1')-SC1delay min +SC2delay max (3)
wherein, SC1delay min Represents the minimum delay of the switch network from the time Server to the first time Client1, SC2delay max Represents the maximum delay of the switch network from the time Server to the second time Client2.
The specific calculation process of the maximum delay and the minimum delay of the switch network is as follows:
calculating an upper bound of delay generated when the data frame is transmitted in the switch network, that is, calculating an upper bound of end-to-end delay of the data frame on any VL Path in the switch network, and defining the upper bound of delay as a time difference between the following two events:
(1) The first byte of the data frame enters the input port of the first switch of the VL Path;
(2) The first byte of the data frame exits from the output port of the last switch of the VL Path.
Referring to the term Node, the Node is explained as follows:
the starting node: a source terminal of VL; the termination node: a destination terminal for VL; a switch node: VL is passed through a certain output port of the switch, each switch having N nodes.
Specifically, the time delay of the data transmission of the switch system is mainly divided into three parts,
the first part is the delay of the switch data reception module, denoted L 1 The duration between the following two events is described:
(1) The first byte of the frame (including the 20 bytes of the preamble, the beginning of the frame delimiter and the interframe space) arrives at the input port of the switch;
(2) The last byte of the frame arrives at the input port of the switch (including the 20 bytes of the preamble, the start of the frame delimiter, and the interframe space);
L 1 representing the maximum value of the duration.
Frames passing through one switch egress port (switch node) may come from one or more switch ingress ports with different bandwidths. L can be calculated according to the following formula 1 ：
VL i E.node represents VL i From the point of the switch to the point of the switch,
is VL i Maximum frame length of C i Is VL i At the input of the exchangeThe bandwidth of the port.
The second part is that when all ports of the switch have data frames with the maximum frame length simultaneously, the interior of the switch needs to carry out error filtering and flow control in sequence, and the data frames are stored in a public buffer area, delay is introduced in the process of waiting for the data frames of other ports to be processed, and the delay is marked as L 2 Described are the durations of two events:
(1) The last byte of the frame arrives at the input port of the switch;
(2) The first byte of the frame arrives in the common buffer;
L 2 representing the maximum jitter due to contention between frames over this duration, which is a fixed value, in part related to switch design.
The third part is the delay of the output port of the switch, which is marked as L 3 The output buffer collects all the VLs output from that port, and each output port consists of two queues, one for buffering data frame traffic for the high priority VL and one for buffering data frame traffic for the low priority VL. In this module, the frames all adopt a first-in first-out scheduling mode. And for any priority, a network algorithm can be adopted to respectively give service curves of high-priority traffic and low-priority traffic. In the high-low priority queue, all high-low priority VLs are aggregated into one data stream: that is, for each priority, the output queue is modeled as an aggregation server that provides an arrival curve to aggregate all VLs within that priority.
The method comprises the following steps: an arrival curve of the first hop of each VL Path is calculated, and for each VL Path, one hop represents an exit from one device (switch or end system) to the next.
A single virtual link arrival curve may be represented in the following form: α (t) = σ + ρ t (5)
Wherein: σ is the maximum traffic that can be reached in bursty traffic, and ρ is the upper slope limit for traffic growth.
Fig. 4 is an arrival curve of a virtual link at an output port of a source terminal, where upward shifting of the curve is a rational amplification of arrival traffic, and a first arrival curve of VL Path can be obtained as follows:
wherein: s max It represents the maximum frame length, BAG is the inherent parameter frame interval of the virtual link, max _ Jitter should be Jitter in the first hop switch ES Denotes VL i Jitter already present in the source terminal. Starting from the second jump, the formula obtained in step four should be used as the arrival curve of VL.
Step two: calculating a service curve of each switch node, and for an aggregated data stream with a high priority VL, at a switch node, waiting for a frame with a low priority being sent due to non-preemptive reasons; for the aggregate data stream of the low-priority VL, it is necessary to wait for all the aggregate data streams of the high-priority VL to be sent, so that the following service curve of the aggregate data stream of each priority VL is obtained:
where L ∈ L denotes a low priority VL passing through the same node i Where l ∈ H denotes a high priority VL passing through the same node i (ii) a When T is more than or equal to 0 and less than or equal to T tech When the utility model is used, the water is discharged,
when t is>T tech When the utility model is used, the water is discharged,
T tech the technical delay for the switch is a fixed value, determined by the switch design.
The service curve for each priority may be written in the form:
β h (t)＝R[t-T] + ,R＝C,
β l (t)＝R[t-T] + ,
wherein the content of the first and second substances,
the maximum value of the maximum frame lengths of all low-priority VLs output from the same node;
all high priority VL for the node passing i Is calculated as the sum of the bandwidths (bytes/ms). T is tech Is the technical delay of the switch. And C is the bandwidth of the node.
Step three: an aggregate arrival curve for each node is calculated. For the output port of the switch, different virtual links cannot be transmitted simultaneously, and therefore, the data transmission is not only constrained by the link bandwidth but also by the aggregation arrival curve, and the data stream traversing on the same node can be regarded as an aggregate stream, as shown in fig. 5, the arrival curve α of the VL aggregate stream passing through the same switch input port SL (t), expressed as:
where SL represents all virtual links through a switch input port of the same switch node, and i ∈ SL represents the virtual link VL through that input port i 。
Inflection point e is represented as:
wherein: sigma i Is VL i Burst traffic through the input port; rho i Is VL i The bandwidth of (d); c is the rate of the input port.
When calculating the aggregation arrival curve, sorting inflection points of the arrival curve of all the N input ports passing through the same output port in ascending order by using a grouping technology, and marking the sorted inflection points as E g (g =1, 2.. Ang., N) (N is the number of physical ports of the switch), as shown in fig. 6. The aggregated data streams of the input ports after ascending packet order are converged at the switch node, and an arrival curve at the switch node can be obtained, as shown in fig. 7, wherein
Thus, the arrival curve and the service curve of the switch node are both obtained, and the maximum delay caused by queuing competition of the data streams at the switch node can be obtained by calculating the maximum horizontal distance between the arrival curve and the service curve, as shown in fig. 7 and 8, and the delay is marked as D max 。
In both FIG. 8 and FIG. 9, there is a inflection point E x On the left side of Ex, the slope of the arrival curve is equal to or greater than the slope of the service curve, and on the right side of Ex, the slope of the arrival curve is less than the slope of the service curve.
When t = EX, the maximum horizontal distance D between the arrival curve and the service curve can be obtained max Is L 3 。
T and R are service curves of the switch node (beta (T) = R [ T-T)] + ) The parameter (c) of (c).
The intermediate parameter y is calculated according to the following equation:
in the formula: m1 is the number of 10Mbps ports in the switch, m2 is the number of 100Mbps ports in the switch, m1+ m2= N-s + 1, m2 first decreases by 1 as s increases by 1, when m2 decreases to 0, m1 starts decreasing by 1 as s increases by 1, C1 is 10mbps, C2 is 100mbps, r0= e0=0.
Step four: the arrival curve of the next node is calculated. By using
VL representing an entry node n i Arrival curve of data stream, using
Denotes VL i The data stream leaves the arrival curve of node n, i.e. passes through node n and enters the arrival curve of the next node. They satisfy the following relationship:
wherein the content of the first and second substances,
is D of node n max Then, we can get:
wherein the content of the first and second substances,
step five: the maximum delay of VL Path in a switch is calculated, and the maximum delay of the switch through which VLi passes should be calculated according to the following equation:
wherein, the first and the second end of the pipe are connected with each other,
represents the maximum delay of VLi through switch j, L1 represents the upper limit of the frame delay in the input module of the switch; l2 represents an upper limit of frame jitter in the address queue; l3 represents the maximum horizontal distance D between the switch node out-of-reach curve and the service curve max 。
The upper end-to-end delay limit of a VL Path in a switch network should be equal to the sum of the maximum delays of all switches passed by the VL Path, that is:
SW j ∈PATH i represents VLPATH i A set of switches that pass through.
Switch minimum latency is to consider the case where there is no virtual link contention when a frame passes through the switch, when L 1 、L 2 The calculation method is the same as above, L 3 Is 0.
The invention designs a method for verifying the time integrity of the ARINC664 network receiving terminal by defining the time management function, so that the message is received in a reasonable delay range, certain data transmission errors are avoided, and the time integrity of the ARINC664 network terminal is ensured.
Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.
Claims (10)
1. An ARINC664 network receiving terminal time integrity checking method, characterized in that the method comprises:
s1, acquiring a DTS (delay tolerant service) of the time when a first byte of a message leaves a sending terminal;
s2, calculating a time deviation TOS between the sending terminal and the receiving terminal;
s3, obtaining a delay upper bound T _ worst of the message in the switch network;
s4, if a receiving end clock when the first byte of the message reaches the receiving terminal is within an upper bound of DTS + TOS + T _ worst, the time integrity check of the message is considered to be passed; and when the receiving end clock exceeds the upper bound of the DTS + TOS + T _ worst, the receiving terminal considers that the time integrity check of the message fails and discards the message.
2. The method according to claim 1, wherein S1 specifically comprises:
and obtaining the data DTS by means of time stamping at the moment that the first byte of the message leaves the sending terminal.
3. The method of claim 1, wherein, in calculating the time offset TOS between the sending terminal and the receiving terminal, S2:
s21, firstly, residing an application software on a general processing module GPM in the ARINC664 network, for constructing and sending a time request message, and using the general processing module GPM as a time Server;
s22, setting other devices capable of carrying out network communication in the ARINC664 network as time Client terminals, wherein each time Client terminal is resident with application software and is responsible for constructing a time response message and sending the time response message to a time Server;
s23, defining a time Server to stamp the message at the moment when the first byte of the message leaves the sending terminal, and a time Client to stamp the message at the moment when the first byte of the time request message is received;
s24, then the time Client constructs a time response message, records the values of two timestamps in the time response message, and sends the time response message to the time Server;
s25, after receiving the time response message, the time Server constructs a time stamp list message, puts the time stamp data collected from each time Client into the time stamp list message, then sends the time stamp list message to each time Client, and finally carries out time deviation calculation on the time Client.
4. The method for checking the time integrity of the ARINC664 network receiving terminal of claim 3, wherein in S2, the terminal connected with the time recording server is used as the sending terminal, and the terminal connected with the time Client1 and the Client2 is used as the receiving terminal;
the time deviation among the local clocks of the time Server, the first time Client1 and the second time Client2 is assumed to satisfy the following relationship:
the time of the first time Client1 is delta 1 faster than the time of the time Server; the time of the second time Client terminal Client2 is delta 2 faster than the time of the time Server terminal Server; and the time of the first time Client1 is faster than the time of the second time Client2, the time offset TOS = Δ 1- Δ 2 between the first time Client1 and the second time Client2.
5. The ARINC664 network receiving terminal time integrity checking method of claim 4, characterized in that D1 represents the switch network path delay from the time Server to the first time Client1, D3 represents the switch network path delay from the time Server to the second time Client 2;
the time Server sends a time request message to a first time Client1, a time stamp is marked on the message when a first byte of the time request message leaves, the time request message is marked as T1, and the first time Client1 stamps the message at the moment of receiving the first byte of the time request message, and the time request message is marked as T2;
the time Server sends a time request message to a second time Client2, and stamps a time stamp on the message when a first byte of the time request message leaves, which is recorded as T1', and the second time Client2 stamps the message at the moment of receiving the first byte of the time request message, which is recorded as T2';
then:
therefore, the time offset between the first time Client1 and the second time Client2 is:
TOS＝Δ1-Δ2
＝T2-T1-D1-(T2'-T1'-D3)
＝T2-T1-(T2'-T1')-D1+D3
6. the ARINC664 network receiving terminal time integrity checking method of claim 5, wherein the upper bound of TOS is:
TOS max ＝T2-T1-(T2'-T1')-SC1delay min +SC2delay max
wherein, SC1delay min Represents the minimum delay of the switch network from the time Server to the first time Client1, SC2delay max Represents the maximum delay of the switch network from the time Server to the second time Client2.
7. The method of claim 1, wherein the ARINC664 network of switches comprises a plurality of switches; s3, obtaining the delay upper bound T _ worst of the message in the switch network, specifically:
s31, determining the maximum time interval from the time when the first byte of the data frame reaches the input port of a certain switch to the time when the last byte of the data frame reaches the input port of the switch, and recording as L1;
s32, determining the time interval from the time when the last byte of the data frame arrives at the input port of the switch to the time when the first byte of the data frame arrives at the public buffer zone of the switch, and recording as L2;
s33, determining the maximum delay of the data frame at the output port of the switch, and recording as L3;
s34, calculating the maximum delay of the data frame in the switch according to the sum of the L1, the L2 and the L3;
and S35, determining the upper delay bound of the data frame in the ARINC664 switch network according to the number of the switches contained in the ARINC664 switch network and the maximum delay of the data frame in each switch.
8. The method of claim 7, wherein the virtual link defines a logically unidirectional connection, from a source terminal to one or more destination terminals, as many VL paths as there are destination terminals in a virtual link, as there are VL paths from the source terminal to a destination terminal;
in S31:
wherein, VL i Representing the ith virtual link and the node representing a certain output port of the switch, called switch node, VL i E node represents the set of virtual links passing through the switch node,
is the maximum frame length allowed by the ith virtual link, C i Is the bandwidth of the ith virtual link at its input port;
in S32: the value of L2 is the maximum jitter time configured by the switch.
9. The method according to claim 7, wherein in S33, the specific process of calculating L3 is as follows:
(a) Calculating an arrival curve of each VLPath, wherein for each VLPath, one hop represents going from the exit of one device to the exit of the next device;
the single virtual link arrival curve is represented as: α (t) = σ + ρ t
Wherein, σ is the maximum flow which can be reached in the burst flow, and ρ is the slope upper limit of the flow increase;
(b) Calculating a service curve for each switch, the service curve comprising: service curve beta for high priority data frames h (t) service curve β for low priority data frames l (t)；
β h (t)＝R[t-T] + ,
β l (t)＝R[t-T] + ,
Wherein, [ T-T ]] + Indicates that when T-T is greater than zero, [ T-T] + Is equal to T-T, when T-T is less than or equal to zero, [ T-T] + Is equal to zero and is,
is the maximum of the maximum frame lengths of all low priority virtual links output from the same node,
is the sum of the bandwidths of all the high priority virtual links through the node,
is the sum of the burst data volume, T, of all high priority virtual links passing through the node tech Is a switchC is the bandwidth of the output port of the switch;
(c) Determining an aggregate arrival curve alpha for all virtual links within a single input port traversing the same output port SL (t)；
Where SL represents all virtual links through a switch input port of the same switch node, and i ∈ SL represents the virtual link VL through that input port i ；
The inflection point e of the polymerization curve is represented as:
wherein σ i Is the ith virtual link VL i Burst traffic through the input port; rho i Is the ith virtual link VL i The bandwidth of (d); c is the rate of the input port;
(d) Sorting inflections of the arrival curves of all N input ports passing through the same output port in ascending order by using a grouping technique, the sorted inflections being identified as E g (g =1,2,. N), N being the number of switch ports; aggregating the input port aggregated data flow after the ascending sorting of the packets at the switch node to obtain an arrival curve at the switch node;
the maximum horizontal delay D caused by queuing competition of data flows at the switch nodes can be obtained by calculating the maximum horizontal distance between the arrival curve and the service curve of the switch nodes max And is denoted as L3.
10. The method of claim 9, wherein (a) the arrival curve of each VLPath is calculated by:
(a1) The first hop arrival curve for each VLPath:
wherein S is max Representing the maximum frame length allowed by the virtual link, BAG being the minimum frame interval of the intrinsic parameters of the virtual link, max _ Jitter representing the maximum Jitter time on the virtual link, and max _ Jitter being Jitter in the first hop switch ES Indicating the jitter of the virtual link already existing in the source terminal;
starting from the second jump, using the formula obtained in the following step as an arrival curve of the virtual link;
(a2) Calculate the arrival curve for the next hop of VLPath:
wherein the content of the first and second substances,
is the maximum latency of the aggregate arrival curve in the node,
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