CN101175134A

CN101175134A - Method for T.38 gateway processing non-standard frame

Info

Publication number: CN101175134A
Application number: CNA2007101814717A
Authority: CN
Inventors: 李瑞华
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2005-02-03
Filing date: 2005-02-03
Publication date: 2008-05-07

Abstract

The present invention relates to a method by which a T.38 gateway processes nonstandard frames, wherein, the T.38 gateway at least includes a transmission gateway and a receiving gateway, the transmission gateway is connected with a transmission fax machine, and the receiving gateway is connected with a receiving fax machine. The method includes three steps; a) the transmission and the receiving gateways conduct judgements on all V.21 frame types; b) after receiving a NSF nonstandard frame, the receiving gateway or the transmission gateway modifies the NSF nonstandard frame, so that the corresponding receiving fax machine or the corresponding transmission fax machine cannot receive the correct NSF nonstandard frame; c) the receiving gateway or the transmission gateway packets or modulates the modified NSF frame data, which are then continuatively sent out. By the processing of the gateway, the method of the present invention modifies the fax rate negotiation performed by a fax flow according to private frames into the negotiation according to standard frames, thus ensuring that the gateway can correctly extract a rate parameter, and guaranteeing the normal operation of network fax.

Description

T.38 gateway is to the processing method of non-standard frame

Technical field

The present invention relates to a kind of fax through internet technology, in particular, in the fax through internet T.38 gateway to a kind of processing method of non-standard frame NSF and NSS.

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, Fax over IP is that the correlation technique of fax through internet is just arisen at the historic moment.T.38 the IP real-time fax is a kind of Fax over IP technology with good anti-Network Packet Loss, shake ability, is used widely in the NGN network.T.38 the real-time fax system configuration is illustrated in fig. 1 shown below, in IP real-time fax system, what carry out between two terminal facsimile machine 1 and 2 is real time communication, the fax flow process is followed T.30 agreement, two facsimile machines are in facsimile, carry out Signalling exchange or packet sending and receiving, when facsimile machine is modulated the data process gateway that sends, gateway can carry out demodulation to the signal of modulation, demodulated data is broken into the T.38 IP bag of agreement regulation, mail to the other side's gateway by IP network, the opposite end gateway splits out data from the IP bag, and modulation sends to corresponding facsimile machine.

Common Facsimile Machine usually support with ITU-T V.27ter/V.29/V.17 agreement specified modulation demodulation rate send the message of the fax page.In agreement T.30, facsimile posting is divided into 5 stages, wherein stage B is a process before the message, as shown in Figure 2, the negotiation of the ability of faxing and training: at first called transmitter is called facsimile machine transmitting capacity sign DIS (Digital identification signal, be the digital identification signal that the fax recipient sends), also has user's marker frames CSI or NSF (Nonstandard facilities, non-standard equipment frame: some attribute not definition in the ITU standard of this message explanation fax operation, this attribute is encoded in FIFO, but not definition of coded system) signal; The caller transmitter is that feedback received order DCS after the caller facsimile machine was received this signal, this order provides about modulator speed, picture traverse, image encoding and page length aspect information, non-standard equipment order NSS (Nonstandard setup) signal that also has the user profile frame TSI signal that has its telephone number or reply the NSF frame sends training signal TCF then; Called transmitter feeds back reception confirmation signal CFR after receiving tcf signal again.

In the stage B of the flow process of should faxing shown in Figure 2, this stage training signal TCF sends full remainder certificate with the rate modulation that the ITU-TV.27ter/V.29/V.17 agreement is stipulated, other signals, as ability sign ((NSF) be DIS (CSI)), reception order ((TSI) DCS), confirmation of receipt (CFR) all is to send, receive with speed and modulation system that the ITU-TV.21 agreement is stipulated, and form is the frame of HDLC.V.21 the HDLC frame format of signal as shown in Figure 3.

In addition, comprise in the T.38 IFP of the complete V.21 frame bag: indication bag V.21flag, i.e. t30-ind, the indication bag that the sign sequence before the frame data is beaten; V.21 frame data bag, i.e. hdlc-data, the frame data packing before from the address field to FCS can break into a plurality of bags; FCS check results bag, promptly hdlc-fcs-ok or hdlc-fcs-bad if the frame data that the gateway demodulate reception arrives are correct, play the hdlc-fcs-ok bag; If mistake is played the hdlc-fcs-bad bag; V.21 frame end bag, i.e. sig-end, the V.21 frame signal energy of gateway demodulate reception disappears.

After called facsimile machine enters stage B, initiatively send (CSI) DIS of ability label signal (NSF), wherein NSF, CSI are for selecting frame for use, the information bit of DIS frame signal has been carried the performance parameter of this facsimile machine, comprises characteristics such as modulation agreement that facsimile machine supports in the message transmissions stage, coded format, ECM mode.After the caller facsimile machine is received DIS, can be according to the called facsimile machine ability of carrying among the DIS, go out the common ability parameter of supporting of both sides in conjunction with self capability negotiation, send to called facsimile machine by DCS.Called facsimile machine will determine which kind of speed to carry out the channel training and the demodulate reception fax page with according to the DCS parameter.

In IP real-time fax T.38, DCS sends gateway and receives gateway and will extract the parameter of DCS, to realize modulation, the demodulation of gateway to TCF data and message data during through gateway.Because DCS is an agreement specified standard frame T.30, agreement has definition to the meaning of each bit position representative of the information field of DCS, so gateway can extract the parameter of DCS and parse information such as speed.

T.30 stipulating in the agreement that in the fax stage B, facsimile machine can also wait parameters such as negotiated speed by non-standard equipment signal NSF/NSS.Described non-standard equipment signal in the negotiated speed flow process of stage B as shown in Figure 4, enter stage B after, called facsimile machine transmitting capacity sign NSF/ (CSI)/DIS, wherein CSI is for selecting frame for use.The information field of NSF comprises information such as how country code, vendor code, facsimile machine model, the rate parameter of facsimile machine manufacturer will carry, the caller facsimile machine is received this non-standard capabilities sign nsf signal, if the caller facsimile machine meets the privately owned regulation of called facsimile machine manufacturer, to reply off-gauge reception order NSS signal, in the NSS frame, carry the result who consults: speed, information such as ECM mode whether; The process that follow-up transmission training signal TCF and described called facsimile machine receive training signal transmission reception confirmation signal CFR is identical with standard frame.But when T.38 gateway carries out fax through internet, because the form of NSF, NSS is the privately owned definition of facsimile machine equipment vendor, T.38 gateway has no idea to extract the indispensable parameter that modulation needs, and therefore under the situation that adopts non-standard frame, facsimile posting must be failed.

Therefore, the gateway of prior art is to TDM (Time Division Multiplexing, time division multiplexing) the side demodulate reception to V.21 frame and the V.21 frame type received of IP side all judge, if the TDM side is received NSF, as shown in Figure 5, to carry out discard processing to NSF, promptly the NSF frame data not being packed sends to the IP side.Like this, that machine sends if receive faxes is NSF/ (CSI)/DIS, because gateway is to the discard processing of NSF, actual arrive send facsimile machine have only (CSI)/DIS signal, send facsimile machine and reply T.30 agreement specified standard frame (TSI)/DCS, DCS has carried information such as modulation speed, ECM mode.

If the IP side is received the NSF frame signal, as shown in Figure 6, gateway receives that to the IP side NSF frame signal does discard processing, this frame data modulation is not sent to the transmission facsimile machine, continues to receive continuous (the CSI)/DIS frame in IP rear flank, and (CSI)/DIS normal modulation is sent.

In the above-mentioned solution, though in the ordinary course of things, can realize that facsimile machine is with standard commands DCS bearer rate information by the discard processing of gateway to NSF.But this scheme has following shortcoming:

T.30 agreement regulation: sends single V.21 frame or send a plurality ofly continuously V.21 before the frame, transmit a string flag sequence of 1s ± 15% earlier, with the 0x7e that V.21 modulates; Through receiving and detected arbitrary frame greater than 3.45s abandons.

As shown in Figure 7, because gateway abandons the NSF frame, sending gateway is just to begin to send 0x7e to the facsimile machine modulation from first flag (0x7e) that receives targeting sequencing, up to receiving follow-up DIS frame, the chance of receiving faxes like this thinks that DIS is first frame signal, and 0x7e before is a targeting sequencing.Some facsimile machine just picks up counting from receiving first 0x7e, can not receive DIS in the 3.45s, just thinks to receive the order failure.

Secondly, the initial condition of gateway all is the voice attitude, just switches to FAX mode as the characteristic signal CED that detects fax or V.21flag after (lead code of (NSF)/DIS).

In the practical application of gateway; occur making that the gateway switch speed is slow or receiving gateway through regular meeting to situations such as fax event detection failures because of soft switch networking complexity; because T.38 gateway can only carry out at FAX mode T.38 the intervention of nsf signal; therefore; when both of these case occurring; can cause NSF to arrive and send facsimile machine at voice status transparent transmission (with voice mode); as shown in Figure 8; the transmission facsimile machine that meets privately owned regulation can be replied the NSS signal; rate consulation is still undertaken by privately owned frame; like this, T.38 gateway just switches to behind the FAX mode can't the extraction rate parameter, thereby causes fax failure.

Therefore, there is certain defective in prior art, and awaits improving and development.

Summary of the invention

A kind of T.38 gateway that the object of the present invention is to provide is to the processing method of non-standard frame, by gateway non-standard frame NSF, NSS are made amendment, make network facsimile machine finally carry out rate consulation with standard frame, gateway extracts correct parameter information from standard commands DCS, so that fax through internet is normally carried out.

Technical scheme of the present invention is:

A kind of T.38 gateway is to the processing method of non-standard frame, and described T.38 gateway comprises that at least one sends gateway and and receives gateway, and described transmission gateway connects one and sends facsimile machine, and described reception gateway connects the machine of receiving faxes, and described method comprises:

A), described transmission gateway or described reception gateway to receive all V.21 frame type judge;

B), when described reception gateway or described transmission gateway receive the NSF non-standard frame, this NSF non-standard frame made amendment makes receive faxes machine or send facsimile machine and can't receive correct NSF non-standard frame of correspondence;

C), described reception gateway is modulated follow-up supervention with the packing of amended NSF frame data or described transmission gateway with amended NSF frame data and is sent.

Described processing method, wherein, described modification to the NSF non-standard frame comprises wherein country code byte is revised as the numeral that does not have national title corresponding with it, and to equipment vendors' byte and other parameter word joint random modification.

Described processing method also comprises:

D), described transmission gateway when detection receives the NSS frame, the NSS frame data are packed sends to network side, regardless of the actual check results of the FCS of this frame, all the FCS check results of this frame is played the FCS-BAD bag; Then these NSS frame data are packed and continue to send.

Described processing method also comprises:

E), described reception gateway is when detection receives the NSS frame signal, described reception gateway is received NSS frame and frame check IFP bag as a result, regardless of check results, all force to handle by BAD result, described reception gateway sends to the described machine of receiving faxes with the modulation of NSS frame data, and when sending the FCS Frame Check Sequence of this frame, the value of FCS verification sequence is carried out random modification.

A kind of T.38 gateway provided by the present invention is to the processing method of non-standard frame, to carry out the fax flow process that fax-rate consults with privately owned frame and pass through gateway processes, be revised as by standard frame and consult, guaranteed the correctly scheme of extraction rate parameter of gateway, guaranteed normally carrying out of fax through internet, and guaranteed non-standard frame be transparent to facsimile machine after be converted to handling through consultation of standard frame.

Description of drawings

Fig. 1 is the structural representation of the T.38 grid real-time fax system of prior art;

Fig. 2 is the schematic flow sheet of the stage B in the common fax flow process of prior art;

Fig. 3 is the HDLC frame format schematic diagram of the V.21 signal of prior art;

Fig. 4 is for carrying out the schematic flow sheet of rate consulation by the non-standard equipment frame in the common fax flow process of prior art;

Fig. 5 is the handling process schematic diagram when the TDM side is received the NSF frame in the fax through internet flow process of prior art;

Fig. 6 is the handling process schematic diagram when the IP side is received the NSF frame signal in the fax through internet flow process of prior art;

Fig. 7 causes the long effect schematic diagram of flag for the employing gateway of prior art abandons NSF frame scheme;

Fig. 8 arrives the schematic flow sheet that transmission facsimile machine gateway can't be intervened for the NSF frame of prior art in the voice attitude;

Fig. 9 is the structural representation of described T.38 gateway of the present invention to the NSF frame in the processing method of non-standard frame;

The schematic flow sheet that Figure 10 makes amendment to the parameter of NSF non-standard frame for the reception gateway of the inventive method;

The schematic flow sheet that Figure 11 makes amendment to the parameter of NSF non-standard frame for the transmission gateway of the inventive method;

Figure 12 is the schematic flow sheet that the transmission gateway in the inventive method is handled the FCS check results of NSS non-standard frame;

The NSS non-standard frame schematic flow sheet that modulation sends as FCS check errors frame that Figure 13 receives the IP side for the reception gateway in the inventive method.

Embodiment

Below, will describe preferred embodiment of the present invention in detail.

T.38 in the processing method of gateway of the present invention to non-standard frame, the structure of described NSF non-standard frame comprising facsimile message, is respectively country code, manufacturer's information and other parameter etc. as shown in Figure 9; Gateway to TDM side demodulate reception to V.21 frame and the V.21 frame type received of IP side all judge, if the TDM side is received the NSF frame, described reception gateway with TDM side demodulate reception to the FIF facsimile information field of NSF frame make amendment, as shown in figure 10, wherein the square reception gateway of having represented of shade is revised the information byte of NSF frame, that is: the country code byte in the NSF frame is revised as the numeral that does not have national title corresponding with it, T.35 defined the corresponding relation of national title and code in the agreement at ITU-T, and to equipment vendors' byte and follow-up facsimile message random modification.Amended NSF frame data packing is sent to IP network.After described transmission facsimile machine was received this processing NSF frame later, information such as the country code that extracts from information field, manufacturer were different with oneself, just do not reply the NSS frame signal, but replied standard commands DCS signal according to ability label DIS.

If the IP side sends gateway and receives the NSF frame signal, then as shown in figure 11, the square expression of shade wherein sends gateway the information byte of NSF frame is revised, described transmission gateway is made amendment to the FIF facsimile information field of the NSF frame that the IP side is received, that is: the country code byte in the NSF frame is revised as the numeral that does not have national title corresponding with it, and, will send to facsimile machine after the amended NSF frame data modulation to equipment vendors' byte and follow-up facsimile message random modification.

In addition, in order to prevent that the NSF frame is transparent to the transmission facsimile machine at voice channel with voice coding modes, the transmission facsimile machine that causes meeting privately owned definition is replied the NSS frame, after making that gateway enters worker's 38 fax attitudes, receive the NSS frame still can't the extraction rate parameter etc. information, described gateway carries out following processing: after gateway switches to the attitude of T.38 faxing, to TDM side demodulate reception to V.21 frame and the V.21 frame type received of IP side all judge, if the TDM side is received the NSS frame, as shown in figure 12, on behalf of the transmission gateway, the shade circle among the figure NSS frame check result is forced to change into BAD, the square reception gateway of having represented of shade is revised the information byte of NSF frame, described transmission gateway carries out following processing: send the NSS frame that gateway is received the TDM side, the NSS frame data are packed send to the IP side, no matter the actual check results of FCS of this frame is OK or BAD, all the FCS check results with this frame breaks into the FCS-BAD bag, so can force the machine of receiving faxes to retransmit the NSF frame once more, down-stream is identical with the processing procedure of above-mentioned NSF frame.

If the IP side is received the NSS frame signal, as shown in figure 13, shade circle among the figure represented receive gateway when facsimile machine sends the FCS check results byte of NSS frame mandatory modification check byte, the square reception gateway of having represented of shade is revised the information byte of NSF frame, described reception gateway carries out following processing: receive the NSS frame that gateway is received the IP side, reach frame check IFP bag as a result, gateway sends to the machine of receiving faxes with the NSS data-modulated, when sending the FCS Frame Check Sequence of this frame, no matter check results is OK or BAD, all force to handle, the value of FCS verification sequence is carried out random modification send again by BAD result.

Like this, because the modification to the FCS verification sequence of NSS frame of gateway, the machine of receiving faxes is thought the NSS frame signal mistake of receiving will resend NSF/DIS.Gateway just can be made amendment to the NSF frame of current re-transmission by the method that the NSF content frame is made amendment that provides previously of the present invention, reaches with the standard frame signal DIS of T.30 definition, the purpose that DCS carries out rate consulation.

Should be understood that above-mentioned description at specific embodiment of the present invention is more specific, can not therefore be interpreted as the restriction to scope of patent protection of the present invention, its scope of patent protection should be as the criterion with claims.

Claims

One kind T.38 gateway is to the processing method of non-standard frame, described T.38 gateway comprises that at least one sends gateway and and receives gateway, described transmission gateway connects one and sends facsimile machine, described reception gateway connects the machine of receiving faxes, described method comprises:

A), described transmission gateway and described reception gateway to receive all V.21 frame type judge;

B), when described reception gateway or described transmission gateway receive the NSF non-standard frame, this NSF non-standard frame made amendment makes receive faxes machine or send facsimile machine and can't receive correct NSF non-standard frame of correspondence;

C), described reception gateway is modulated follow-up supervention with the packing of amended NSF frame data or described transmission gateway with amended NSF frame data and is sent.
2. processing method according to claim 1, it is characterized in that, described modification to the NSF non-standard frame comprises wherein country code byte is revised as the numeral that does not have national title corresponding with it, and to equipment vendors' byte and other parameter word joint random modification.
3. processing method according to claim 1 is characterized in that, described method also comprises:

D), described transmission gateway when detection receives the NSS frame, the NSS frame data are packed sends to network side, regardless of the actual check results of the FCS of this frame, all the FCS check results of this frame is played the FCS-BAD bag; Then these NSS frame data are packed and continue to send.
4. according to the described processing method of the arbitrary claim of claim 1～3, it is characterized in that described method also comprises:

E), described reception gateway is when detection receives the NSS frame signal, described reception gateway is received NSS frame and frame check IFP bag as a result, regardless of check results, all force to handle by BAD result, described reception gateway sends to the described machine of receiving faxes with the modulation of NSS frame data, and when sending the FCS Frame Check Sequence of this frame, the value of FCS verification sequence is carried out random modification.