CN101217461B - Gateway and method for processing V.21 frame data - Google Patents
Gateway and method for processing V.21 frame data Download PDFInfo
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- CN101217461B CN101217461B CN2007101810650A CN200710181065A CN101217461B CN 101217461 B CN101217461 B CN 101217461B CN 2007101810650 A CN2007101810650 A CN 2007101810650A CN 200710181065 A CN200710181065 A CN 200710181065A CN 101217461 B CN101217461 B CN 101217461B
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Abstract
The embodiment of the invention discloses a gateway and a method for treating V.21 frame data. The method for treating V.21 frame data comprises the following procedures: the received V.21 frame data is cached; after the V.21 frame data is cached for a certain amount of data, the V.21 frame data which is cached for a certain amount of data is sent; the V.21 frame data which is cached for a certain amount of data is smaller than or equal to a frame of V.21 frame data. The method can solve the problem of facsimile timeout caused by that the V.21 frame data can only be sent after a frame of V.21 frame has been cached.
Description
Technical field
The present invention relates to communication technical field, particularly a kind of gateway and handle the V.21 method of frame data.
Background technology
Along with the maturation of popularizing of using of Internet and technology, make traditional facsimile message be carried on Internet and go up transmission and become possibility that therefore, the correlation technique of Fax over IP is also just arisen at the historic moment.At present the mode that Fax over IP is commonly used is mode (the real-time bearing protocol mode of Group-3 fax machine IP) T.38.T.38 IP real-time fax gateway is mainly finished T.38 protocol processes and DP modulation, and its system configuration as shown in Figure 1.T.38IP the basic thought of fax mode is: at gateway T.38 the data that facsimile machine sends are carried out demodulation, the payload data of demodulation is broken into the T.38 IP bag of agreement regulation, mail to the other side's gateway by IP network; Recipient's T.38 gateway is according to the information characteristic of this IP bag, and the payload data that splits out from the IP bag is modulated again and sent to TDM side facsimile machine.As seen, what the IP real-time fax carried is fax signaling or message information mutual between terminal facsimile machine, and what carry out between two terminal facsimile machine is real time communication, and the fax flow process is followed T.30 agreement (transmission protocol of document facsimile on public switched telephone network).
In agreement T.30, facsimile posting is divided into following 5 stages as shown in Figure 2: stage A is the facsimile call establishment stage, and this stage is similar a bit to the process that call is set up; Stage B is a process before the message, and this stage is mainly carried out the negotiation and the training of ability; Stage C is message transmission procedure and message transmissions control procedure; Stage D is a process behind the message, and this stage is mainly carried out confirmation, the error correction of message, the operation of multipage supervention; Stage E is the process that facsimile call discharges.In above-mentioned fax flow process, except the message data of the TCF training signal of stage B and stage C is by agreement rate modulation V.27/V.29/V.17, other control signalings are all by V.21 modulation, V.21 signal format is HDLC frame (being called V.21 frame), is used for that fulfillment capability is consulted and function such as message confirmation; V.21 frame format as shown in Figure 3.In Fax over IP business T.38, gateway is packed to the V.21 frame of receiving from the demodulation of TDM side, to one V.21 the IFP that gets of frame comprise V.21flag indication bag (t30-ind), V.21 frame data bag (hdlc-data), FCS check results bag (hdlc-fcs-ok or hdlc-fcs-bad), frame end bag (sig-end) V.21.
T.30 agreement has following regulation: the V.21 frame that 1, is sent out is the longest can not to surpass 2.55s (being 3s-15%); 2, through receiving and detected arbitrary frame greater than 3.45s abandons; 2.45s may the abandon between～3.45s; 3, send single V.21 frame or send a plurality ofly continuously V.21 before the frame, transmit a string flag sequence (with the 0x7e of modulation V.21) of 1s ± 15% earlier.And find during the facsimile machine that existing market is used tested, different facsimile machines is in the reception flow process of order or response, to the calculating difference of time of reception: the facsimile machine that has is from receiving that V.21 last 0x7e of frame signal lead flag sequence starts 3s timer (situation 1 facsimile machine); The facsimile machine that has is from receiving that V.21 first 0x7e of the lead flag sequence of frame signal begins to start 3.45s timer (situation 2 facsimile machines), do not receive complete V.21 frame signal if timer has arrived time-out time, then taking defeat.
And for Fax over IP, in order to prevent that frame data interrupt because of V.21 environmental factors such as network delay, shake cause on the PSTN circuit, T.38 gateway must carry out buffer memory with the V.21 frame data of down direction (receiving the direction of data from IP network), and then sends to the modulation of TDM side.Therefore, T.38 gateway of the prior art when descending modulation sends, is done following processing usually: as shown in Figure 4, receive the indication bag v.21flag that gateway receives that the IP side arrives, just begin to send 0x7e, and the V.21 frame data that the IP side is arrived receive buffer memory to the facsimile machine modulation; V.21 frame data buffer memory one frame end, promptly receive the packet of the FCS check results of this frame, gateway begins to send V.21 frame data to the PSTN line modulation, so just can guarantee can not cause that V.21 the frame modulating data is in the PSTN line interruption because of network delay, shake.But, because T.38 this down buffer storage one frame of gateway just begins to modulate the transmit frame data, receive V.21 targeting sequencing indication bag and receive gateway one, just continue modulation and send the 0x7e targeting sequencing, and receive gateway the time to frame data buffer memory V.21, be the 0x7e sequence to what receive faxes the machine transmission also, therefore, the targeting sequencing that the machine of receiving faxes receives has increased V.21 frame length always; And the V.21 frame that sends the facsimile machine transmission is long more, and it is long more to the cache-time of frame data to receive gateway, and the delay that frame data arrive the machine of receiving faxes is big more, and the 0x7e that the machine of receiving faxes receives is long more; And when the 0x7e targeting sequencing adds that the length of frame data has surpassed in the machine of receiving faxes timer expiry thresholding 3s+15% (3.45s), can think for the facsimile machine of situation 2 to take defeat.For example, suppose the long 850ms of targeting sequencing (1s-15%) of the V.21 frame signal that the transmission facsimile machine sends, to the regulation of HDLC frame length V.21, the length that facsimile machine sends all is legal less than the V.21 frame of 2.55s according to agreement T.30, therefore the V.21 frame length 2s that sends of hypothesis; Receive so that targeting sequencing that gateway sends is long to be 2.85s, add the long 2s of frame data of actual transmissions, can in 3.45s, receive scarcely for the machine of receiving faxes of facsimile machine situation 2 and completely V.21 order or respond, cause fax failure at last.
This shows, this scheme is under the situation that V.21 frame is grown, because carrying out buffer memory one frame to frame V.21, gateway sends, may cause the 0x7e targeting sequencing before the V.21 frame signal that the machine of receiving faxes receives long, the V.21 order that comprises targeting sequencing or the response time that make facsimile machine receive exceed overtime thresholding, cause fax failure.
Summary of the invention
The embodiment of the invention provides the V.21 method of frame data of a kind of gateway and a kind of processing, solve gateway buffer memory one frame V.21 frame just send V.21 frame data and cause the overtime problem of some facsimile machine.
A kind of processing is the method for frame data V.21, may further comprise the steps:
The V.21 frame data that receive are carried out buffer memory;
After the certain data volume of described V.21 frame data buffer memory, send the V.21 frame data of the certain data volume of described buffer memory;
V.21 the frame data of the certain data volume of described buffer memory are smaller or equal to frame frame data V.21.
A kind of V.21 gateway of frame data of handling, it comprises:
Be used for the V.21 frame data that receive are carried out the member of buffer memory;
After being used for the certain data volume of described V.21 frame data buffer memory, send the member of the V.21 frame data of the certain data volume of described buffer memory;
V.21 the frame data of the certain data volume of described buffer memory are smaller or equal to frame frame data V.21.
Above-mentioned gateway or handle the V.21 method of frame data, by will be V.21 just sending the V.21 frame data of the certain data volume of described buffer memory after the certain data volume of frame data buffer memory, make that V.21 the frame data cache-time shortens, so can solve gateway because of buffer memory one frame V.21 frame send just V.21 that frame data cause the overtime problem of some facsimile machine.
Description of drawings
Fig. 1 is real-time fax system configuration T.38;
Fig. 2 is the Fax over IP typical flowchart;
Fig. 3 is frame format figure V.21;
Fig. 4 handles schematic diagram for the prior art down direction;
Fig. 5 handles schematic diagram for down direction of the present invention.
Embodiment
With embodiment the present invention is described in further detail with reference to the accompanying drawings below:
In order to prevent that network jitter from causing gateway when V.21 facsimile machine sends data, data interruption on the PSTN circuit, it is necessary that gateway carries out to the V.21 frame data of downstream IP side that the buffer memory modulation sends.The prior art scheme is no matter V.21 frame length how, all completely sends and handles by receiving a complete frame buffer; And the present invention will be V.21 frame data divide the growth frame and two kinds of situations of short frame are adjusted buffer storage length, take different method for caching and processing.Method of the present invention may further comprise the steps:
A, same as the prior art, gateway receive V.21 flag indication bag of IP side, just begin to send v.21 flag preamble sequence to the modulation of TDM side.
The V.21 frame data that B, described gateway are received the IP side joint carry out buffer memory; Different is set a data cached length, and described data cached length to be provided with according to the maximum jitter that network may occur with prior art.Data in buffer amount (data cached length) requirement can be resisted the shake that IP network may occur, and concrete numerical value can be set according to present real network situation; Usually, relatively poor network environment, network jitter is no more than 100ms; Suppose that gateway need have the ability of anti-200ms shake, the data cached length of setting is at least 8bytes (0.2 * 300bps/8=8bytes).
C, will be V.21 frame data be divided into long frame and short frame, promptly V.21 frame length is more than or equal to the long frame that is of data cached length, V.21 frame length is the weak point frame less than data cached length; By a frame buffer, promptly beginning sends V.21 frame data to the modulation of TDM side to gateway behind buffer memory one frame to short frame; And for long frame, when the data in buffer amount arrived described data cached length, no matter whether be cached to a complete frame, described gateway all will begin to send V.21 frame data to the modulation of TDM side.
For step C, comprise following concrete step:
Whether C1, described gateway reach described data cached length and whether be cached to frame data in described data cached length the described V.21 frame data of buffer memory is judged simultaneously;
If C2 data in buffer amount has reached predefined data cached length, described gateway begins to send described V.21 frame data to the modulation of TDM side, continues to receive these frame data simultaneously; After this data volume of this frame is no longer judged, when receiving next frame, carried out identical buffer memory and judgement again;
C3, when the data in buffer amount is made a decision, judge whether the complete frame that has been cached to; If in data cached length, gateway has been received the V.21 packet of the FCS check results of frame data, just assert to receive complete frame data, begins these frame data are modulated transmission.
Owing to adopted technique scheme, when gateway sends in descending modulation, can regulate automatically according to frame length is to send V.21 frame data by buffer memory one frame or the certain data volume modulation of buffer memory, thereby solved prior art under long frame condition, cause some facsimile machines to receive the problem of order and response timeout, fax failure because of gateway buffer memory one frame just sends data, improved the compatibility of gateway and facsimile machine; Simultaneously, because gateway is to determine according to the network jitter that IP network may occur to the data cached length that needs the data in buffer setting, therefore cancellation network is shaken the transmission interruption of V.21 frame data on the PSTN circuit that causes well, has good anti-network jitter, lag characteristic.
In addition, according to the regulation of agreement T.30, facsimile machine sent in time of order back 3s V.21 will receive the response signal of opposite end facsimile machine to order; The inventive method is owing to the minimizing of gateway cache-time, and the function of receiving faxes is earlier received complete V.21 order, and replys response signal.Thereby shortened the time that facsimile machine is received response that sends; Order and the mutual reliability that responds have been improved under IP network delay situation.
Below the V.21 frame that still sends with the facsimile machine of prior art scheme is that example illustrates: the long 850ms of frame preamble sequence (1s-15%) V.21, frame length 2s; The value of setting of supposing data cached length is 6Bytes (160ms duration, network jitter that can anti-160ms), receive the long 1.01s (0.850s+0.160s) of being of targeting sequencing that gateway sends so, add data frame length 2s, the frame data length that receives for the machine of receiving faxes of facsimile machine situation 2 is 3.01s, and order, the response that can not exceed 3.45s receive timer duration.This shows that the inventive method has solved prior art under long frame condition, cause some facsimile machines to receive the problem of order and response timeout, fax failure, improved the compatibility of gateway and facsimile machine because of gateway buffer memory one frame just sends data (processing); Cancellation network is shaken the transmission interruption of V.21 frame data on the PSTN circuit that causes well simultaneously.The technical program is applied in gateway device, facts have proved, this scheme has good compatibility to facsimile machine, and has good anti-network jitter, lag characteristic.
Be understandable that, for those of ordinary skills, can be equal to replacement or change according to technical scheme of the present invention and inventive concept thereof, and all these changes or replacement all should belong to the protection range of the appended claim of the present invention.
Claims (5)
1. handle the V.21 method of frame data for one kind, may further comprise the steps:
The V.21 frame data that the IP side joint is received carry out buffer memory;
When described V.21 frame is long frame, when the length of buffer memory reaches the definite value of setting, send described V.21 frame to the modulation of TDM side; Described long frame is the described V.21 frame of frame length more than or equal to described definite value;
When described V.21 frame is the weak point frame, send described V.21 frame to the modulation of TDM side behind buffer memory one frame; Described short frame is the described V.21 frame of frame length less than described definite value;
Described definite value is set according to the shake that network may occur.
2. method according to claim 1 is characterized in that: described definite value is 8 or 6 bytes.
3. method according to claim 1 is characterized in that: further comprise step:
When described V.21 frame when the long frame, when the length of buffer memory reaches the definite value of setting, when the modulation of TDM side sends described V.21 frame, continue the data of the described V.21 frame of reception.
4. can handle the V.21 gateway of frame data for one kind, it is characterized in that, comprise:
Be used for the V.21 unit of frame data of buffer memory;
Be used to receive the V.21 frame data that the IP side joint is received, it is cached to the described V.21 unit of the unit of frame data of buffer memory that is used for;
Be used for when described V.21 frame is long frame, when the length of buffer memory reaches the definite value of setting, send the unit of described V.21 frame to the modulation of TDM side; Described long frame is the described V.21 frame of frame length more than or equal to described definite value;
Be used for when described V.21 frame is the weak point frame, send the unit of described V.21 frame behind buffer memory one frame to the modulation of TDM side; Described short frame is the described V.21 frame of frame length less than described definite value;
Described definite value is set according to the shake that network may occur.
5. gateway according to claim 4 is characterized in that, described being used for when described V.21 frame is long frame, when the length of buffer memory reached the definite value of setting, the unit that sends described V.21 frame to the modulation of TDM side also was used for:
When described V.21 frame when the long frame, when the length of buffer memory reaches the definite value of setting, when the modulation of TDM side sends described V.21 frame, continue the data of the described V.21 frame of reception.
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| CN2007101810650A CN101217461B (en) | 2005-01-26 | 2005-01-26 | Gateway and method for processing V.21 frame data |
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| CN2007101810650A CN101217461B (en) | 2005-01-26 | 2005-01-26 | Gateway and method for processing V.21 frame data |
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| CNB2005100330360A Division CN100342700C (en) | 2005-01-26 | 2005-01-26 | T.38 gatewag contraposed to V.21 frame adaptive regulating down buffer storage length method |
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| CN101217461B true CN101217461B (en) | 2010-12-01 |
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| CN101969437B (en) * | 2010-10-15 | 2013-04-10 | 杭州华三通信技术有限公司 | IP fax method and gateway device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1207848A (en) * | 1995-11-13 | 1999-02-10 | 网络传真公司 | Internet global area network fax system |
| CN1292196A (en) * | 1998-02-25 | 2001-04-18 | 西门子公司 | Mobile telephone with facsimile scanning line |
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- 2005-01-26 CN CN2007101810650A patent/CN101217461B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1207848A (en) * | 1995-11-13 | 1999-02-10 | 网络传真公司 | Internet global area network fax system |
| CN1292196A (en) * | 1998-02-25 | 2001-04-18 | 西门子公司 | Mobile telephone with facsimile scanning line |
Non-Patent Citations (2)
| Title |
|---|
| 孟进，刘立柱.实时IP传真技术及实现.网关与IP技术29 5.2003,29(5),第14页右栏第2行-15页右栏第21行，附图2. |
| 孟进,刘立柱.实时IP传真技术及实现.网关与IP技术29 5.2003,29(5),第14页右栏第2行-15页右栏第21行,附图2. * |
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