CN101127585A - A retransmission mechanism for ISDN user-network interface data link layer - Google Patents
A retransmission mechanism for ISDN user-network interface data link layer Download PDFInfo
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- CN101127585A CN101127585A CNA2007101200715A CN200710120071A CN101127585A CN 101127585 A CN101127585 A CN 101127585A CN A2007101200715 A CNA2007101200715 A CN A2007101200715A CN 200710120071 A CN200710120071 A CN 200710120071A CN 101127585 A CN101127585 A CN 101127585A
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Abstract
The utility model discloses a retransmission mechanism of a data link layer between ISDN users and network interface, belonging to the technical field of network communication. The method stores sending frames through an array; the subscript of the array is corresponding to the sending sequence number of the frames; therefore, when the receiver requires the sender to retransmit, the information frame can be directly found in the array according to the sequence number expected from the receiver to retransmit. Compared with the prior art, the utility model has the advantages of simple and reliable method and improves the implementation efficiency and reliability of the system.
Description
Technical field
The invention belongs to the network communications technology scope, particularly a kind of retransmission mechanism of isdn user-network interface data link layer.
Background technology
In the telephone exchange that uses the ISDN agreement, can stablize, reliably in order to make the ISDN protocol communication, in communication process, must use repeating transmission to the data of losing, with guarantee the recipient complete receive the data that transmit leg sends.
In the national standard of isdn user-network interface data link layer structure, performance variable and the number value of information frame of communication some constraints have been carried out.
Stipulate that each information frame all numbers in order, number value circulates from 0-127.
The sequence number of the next information frame that send state variable V (s): V (s) expression will send in order, V (s) can get the arbitrary value in the 0-127 scope, send an information frame in order at every turn after, V (s) value adds 1.
Confirm that state variable V (A): V (A) is used for representing the last frame (N that sends sequence number (s) of the last information frame that V (A)-1 equals to have confirmed) of having confirmed the opposite end.V (A) can get the arbitrary value in the 0-127 scope.V (A) upgrades according to effective Receive sequence number N (R) value that receives from the opposite end.So-called effectively Receive sequence number N (R) value is the value in V (A)＜N (R)＜V (S) scope.
Send sequence number N (S): N (S) by the sending sequence number of transmission information frame, when sending an information frame, its N (S) should equal send state variable V (S).
The sequence number of the next information frame that accepting state variable V (R): V (R) expression expectation receives.V (R) can get the arbitrary value in the 0-127 scope.Whenever receive a zero defect and the N that sends sequence number (S) when equaling the information frame of accepting state variable V (R), V (R) value just adds 1.
During the information frame of variable V (R), V (R) value just adds 1.
Sending sequence number of the information frame that the next expectation of Receive sequence number N (R): N (R) expression receives.When sending information frame, N (R) value equals accepting state variable V (R) value.N (R) show the data link layer entity that sends this N (R) received accurately sequence number less than with the full detail frame that equals N (R)-1.
2-7 position in 28 bit bytes in the front of information frame is represented the N that sends sequence number (S) and the Receive sequence number N (R) of transmit leg respectively, and the scope of the value of expression is 0-127.
Stipulate also in the national standard of isdn user-network interface data link layer that send state variable V (S) deducts the value of confirming state variable V (A) can not be greater than 7, the maximum number of unacknowledged information frame can not surpass 7 in other words.
The flow process that the information frame at ISDN protocol communication two ends sends and receives is as follows:
After system brings into operation, the value of send state variable V (S), accepting state variable V (R), affirmation state variable V (A), the N that sends sequence number (S) and Receive sequence number N (R) all is 0, before information frame of every transmission, Receive sequence number N (R) equals accepting state variable V (R), the N that sends sequence number (S) equals send state variable V (S), send back send state variable V (S) and add 1, if send state variable V (S) equals 128, send state variable V (S) equals 0.Whenever after receiving an information frame, the recipient checks the N (S) that sends sequence number, the N if send sequence number (S) equals accepting state variable V (R) then confirms state variable V (A)=Receive sequence number N (R), accepting state variable V (R) adds 1, (R) equals 128 when the accepting state variable V, accepting state variable V (R) equals 0, is the information frame of accepting state variable V (R) otherwise the recipient requires transmit leg to send sequence number.
When transmit leg receives that the recipient requires to resend sequence number and is the frame of V (R), the information frame that transmit leg should be worth the accepting state variable V (R) that sequence number requires for the recipient sequence number send state variable V (S)-1 value that transmit leg sent all resends one time, guarantees the information frame of receiving the transmit leg transmission that the recipient can be complete.
The method that adopts when handle retransmitting in view of the prior art switch software is that to open up a capacity be that the information frames that 7 letters send also are kept in this formation, every affirmation once back is disposed the information frame of confirming from this formation, retransmit after searching from formation according to the N that sends sequence number (S) value of expectation when need retransmitting, such processing is for management and to operate this capacity be that 7 re-transmit queue is more loaded down with trivial details, one of every affirmation one less important removing is searched from formation when needs are retransmitted again.
Summary of the invention
The present invention has overcome loaded down with trivial details that information frame is retransmitted in the prior art, and a kind of retransmission mechanism of isdn user-network interface data link layer is provided.
Technical scheme of the present invention is: all circulate from 0-127 according to the transmission of information frame and the sequence number of reception, therefore in the array that can store 128 information frames of definition, be used to preserve the information frame of transmission, each information frame adds 1 by the order that sends and is kept in the array for sending sequence number.
Described sending sequence number as the subscript of this array preserved 128 information frames and enough satisfy the needs that send sequence number (according to the GB requirement, send sequence number and circulate) that transmit leg is retransmitted between 0-127.
It is when the recipient checks that sending sequence number of the information frame received is not equal to sending sequence number that the recipient expects that described transmit leg is retransmitted, the recipient will require transmit leg to resend the information frame that sends sequence number of recipient's expectation, at this moment transmit leg can be directly be that subscript obtains the information frame that the recipient needs from the array of preserving information frame with the information frame that sends sequence number of recipient's expectation, and the information frame that sends sequence number that is designated as down recipient's expectation in the array send sequence number and sending sequence number of transmit leg retransmitted for all information frames between the subscript, make all information frames of receiving that the recipient can be complete, guarantee the reliability service of system.
The invention has the beneficial effects as follows: compare with existing technology, preserve the information frame of all sequence numbers by an array of holding 128 information frames, the sequence number of the information frame that can retransmit is as required directly taken out information frame and is retransmitted from array, method is simple and reliable, has improved the execution efficient and the reliability of system.
Description of drawings
Fig. 1 is the flow chart of the retransmission mechanism of network interface data link layer
Embodiment
Below describe the retransmission mechanism of network interface data link layer in detail by Fig. 1 and embodiment.
The information frame retransmission mechanism concrete steps at ISDN protocol communication two ends are as follows:
Step 1: after system brought into operation, before information frame of every transmission, the N that sends sequence number (S) equaled to send variable V (S); After information frame sends, send state variable V (S)+1, i.e. N (S)=V (S)+1.
Step 2: can store in the array of 128 information frames one of definition, preserve the information frame that sends, each information frame adds 1 for sending sequence number by the order that sends, and is kept in the array; Be in the array of subscript information frame promptly, preserve the content of this information frame with N (S), the information frame of preservation send sequence number N (S), N (S)+1, N (S)+2 ... circulation between the N (S)+127.
Step 3: after the recipient whenever receives an information frame,, and return to response frame of transmit leg with the inspection N (S) that sends sequence number.
Step 4: transmit leg is received the response frame that the recipient sends, and the type of message in the inspection response frame, if refusal just represents that the sequence number N (S) of the information frame that the recipient receives makes mistakes, be that the recipient checks when the N that sends sequence number (S) of the information frame of receiving is not equal to the N that sends sequence number (R) of recipient's expectation, think that then the frame number that the recipient receives makes mistakes, the recipient will require transmit leg to resend sending sequence number of recipient's expectation to be the information frame of N (R); Wherein N (R) represents the sequence number of recipient's expectation.
Step 5: transmit leg is that the information frame of N (R) is a subscript with sending sequence number of recipient expectation directly, from the array of preserving information frame, obtain the information frame that the recipient needs, and be designated as down in the array recipient's expectation send sequence number for the information frame of N (R) send sequence number and the N that sends sequence number (S) of transmit leg retransmits for all information frames between the subscript, with the assurance recipient can be complete receive all information frames.
Claims (2)
1. the retransmission mechanism of isdn user's one network interface data link layer, it is characterized in that: described retransmission mechanism comprises:
(1) array that can store 128 information frames of definition is used to preserve the information frame of transmission, and each information frame adds 1 by the order that sends and is kept in the array for sending sequence number,
(2) described sending sequence number, this time as the subscript of each information frame of this array be designated as 1～128 in any one integer, preserve 128 information frames and enough satisfy the needs that send sequence number that transmit leg is retransmitted.
2. the retransmission mechanism of a kind of isdn user-network interface data link layer according to claim 1, it is characterized in that: it is when the recipient checks that sending sequence number of the information frame received is not equal to sending sequence number that the recipient expects that described transmit leg is retransmitted, the recipient will require transmit leg to resend the information frame that sends sequence number of recipient's expectation, at this moment transmit leg can be that subscript obtains the information frame that the recipient needs from the array of preserving information frame with sending sequence number of recipient's expectation directly, and be designated as down in the array recipient's expectation send sequence number and the subscript that sends sequence number of transmit leg between all information frames retransmit, make all information frames of receiving that the recipient can be complete, guarantee the reliability service of system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2007101200715A CN101127585A (en) | 2007-08-08 | 2007-08-08 | A retransmission mechanism for ISDN user-network interface data link layer |
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| Application Number | Priority Date | Filing Date | Title |
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| CNA2007101200715A CN101127585A (en) | 2007-08-08 | 2007-08-08 | A retransmission mechanism for ISDN user-network interface data link layer |
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| CN101127585A true CN101127585A (en) | 2008-02-20 |
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| CNA2007101200715A Pending CN101127585A (en) | 2007-08-08 | 2007-08-08 | A retransmission mechanism for ISDN user-network interface data link layer |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104079371A (en) * | 2013-03-27 | 2014-10-01 | 成都鼎桥通信技术有限公司 | Method, equipment and system of data communication |
| CN104427640A (en) * | 2013-08-25 | 2015-03-18 | 联芯科技有限公司 | Information sending and receiving method, device and transmission system |
| CN114666007A (en) * | 2022-02-28 | 2022-06-24 | 广东宝莱特医用科技股份有限公司 | UART communication method, device, equipment and storage medium |
-
2007
- 2007-08-08 CN CNA2007101200715A patent/CN101127585A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104079371A (en) * | 2013-03-27 | 2014-10-01 | 成都鼎桥通信技术有限公司 | Method, equipment and system of data communication |
| CN104427640A (en) * | 2013-08-25 | 2015-03-18 | 联芯科技有限公司 | Information sending and receiving method, device and transmission system |
| CN104427640B (en) * | 2013-08-25 | 2017-11-10 | 联芯科技有限公司 | The method, apparatus and transmission system that a kind of information sends and receives |
| CN114666007A (en) * | 2022-02-28 | 2022-06-24 | 广东宝莱特医用科技股份有限公司 | UART communication method, device, equipment and storage medium |
| CN114666007B (en) * | 2022-02-28 | 2023-05-16 | 广东宝莱特医用科技股份有限公司 | UART communication method, UART communication device, UART communication equipment and storage medium |
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