DE19947073A1 - Message transmission method in communications network - Google Patents

Abstract

The method involves transmitting messages which are associated respectively one of, if necessary several communication connections over a common connection, whereby the messages are transmitted in the same sequence at the respective receivers, in which they were originally sent by the pertinent transmitter. The messages are marked with sequence numbers to assure the sequence. At least one message is received outside the original sequence, and is temporarily stored in a reception buffer. A reception of the at least one temporarily stored message is enabled to the receivers at a loss of the connection.

Description

In accordance with ITU-T standards Q.701 to Q.706, "SPECIFICATIONS OF SIGNALING SYSTEM No. 7 "trained narrowband clock The number 7 system is level 3 of message transfer Furthermore - also called "MTP Level 3" - in the ITU-T standard Q.704, "Specifications of Signaling System No. 7 - Message transfer part - signaling network functions and messages " fixed. Then a changeover procedure (changeover procedure), which is used as a character string if a route (signaling link) trained connection the be affected signaling traffic to alternative signaling stretching or switching routes (signaling routes). In two messages (Changeover Order, Changeover Acknowledged gement) of this procedure are done from the level 3 sequence numbers in the ITU-T standard Q.703, "Signaling System No. 7 - Signaling link ", defined level 2 to the respective opposite side of the failed signaling line det. These sequence numbers identify the last one received on the unusual signaling route - and also accepted - message. These sequence numbers are possible Chen, a transmitter at one end of the failed time chengabestrecke, messages that are not yet correctly have reached the opposite side or are not accepted by them were identified, read from the send buffers and again via alternative signaling routes or characters routes to send.

This way, if signaling fails stretch a loss of any after contained in the transmit buffer judge which has already been sent but not yet acknowledged were minimized and the fulfillment of the ITU-T standard Q. 706, "Signaling System No. 7 - Message transfer part signaling performance ", §1.2b claims  relieved regarding message loss. According to §1.2c this ITU-T standards may also be a new, uncoordinated Sen from messages that have already been sent at least once an alternative signaling route or an alternative Signaling path, which also without exchanging the sequence Level 2 numbers would not be possible, as in the Signaling generally doubles message is considered more dangerous than its possible loss. However, there is no absolute guarantee that a Be MTP users all messages and these in the correct order order received. Since such situations in which message lost or exchanged, but as a result of rarity are more or less seen as mistakes, are only rudimentary in the user protocols of the MTP Mechanisms needed to treat them. In general it is sufficient to recognize these situations and single tolerated in such a way that total failure of the users protocols (e.g. as a result of a deadlock) is avoided. Frequently, there are no correction mechanisms for all Si tuations provided in which, even without this, a total loss case is avoided. So z. B. the situation that a call construction as a result of lost or exchanged messages fails without an error message, acceptable if it is very much so rarely occurs.

In the event of certain failures (e.g. failure of one character control section or in the event of failure of the last signaling route between two signaling points) It can happen that the exchange of the changeover after is either not possible at all or that one or both of the affected sequence numbers are not available stand. In such a case, a transmitter may at most the messages that have never been sent from the send buffer read out the unusual signaling route and on one alternative signaling range or an alternative time Send chengabeweg again. This will make a possible one Duplication of messages at the recipient prevented.  

The same switching procedure also comes in accordance with the ITU-T Standard Q.2210, "MTP Level 3 functions and messages using the Services of Q.2140 "trained broadband signaling system number 7 at level 3 of the message transfer part for use. This broadband signaling system is for those Signaling in the broadband ISDN network determines, but could can also be used in the narrowband ISDN network.

Level 3 of this broadband signaling system is one Level 2 used in the ITU-T standards Q.2110, "B-ISDN ATM adaptation layer - Service specific connection oriented protocol (SSCOP) "and Q.2140," B-ISDN ATM adaptation layer - Service specific coordination function for signaling at the network node interface (SSCF AT NNI) ". This Level 2 is also referred to as "SSCOP" in the professional world. While level 3 faces this message transfer part that of the message part of the narrowband signaling system shows only comparatively minor changes, is that of you used level 2 completely new and has only the minor level 3 changes required.

A difference between level 2 of the narrowband character system and that of the broadband signaling system is included for example, that the length of the sequence numbers of the latter is now 24 bits instead of just 7 bits. Therefore for the two messages mentioned above (changeover order, Changeover Acknowledgment) of the changeover procedure new Vari anten to be defined to the longer sequence numbers of the To be able to transmit level 2 with them.

Another feature of the new level 2 is that that from this news which is not in the expected complete order are received, not rejected, but are buffered in a receive buffer. Only after by retransmitting the missing nights straighten the gaps in the news stream have been filled  the cached messages become complete and in the correct order at the receiving end handed over to the SSCOP.

In the event of an SSCOP connection failure that occurs regularly a side effect of a failure of signaling is received, the messages already received in the Reception buffer discarded on the assumption that by means of the before switching procedure described by exchanging the Sequence numbers that are already in the receive buffers characters that have been received but are not yet fully received messages on alternative signaling routes or Signaling routes are transmitted again.

However, as previously described, there are situations in which there is this switching procedure is not possible or only partially possible is to exchange the sequence numbers and subsequently the messages not yet received from the other party - tough If necessary, even those who are not completely received are already in the Messages in the receive buffer - again on the old one native signaling routes or signaling routes In addition to these situations, there are also other situations imaginable where the exchange of sequence numbers is not he follows, e.g. B. if this exchange is generally not carried out is such. B. in the German patent application DE 195 30 322.9 described. In these situations, those in the receiving puff fer contained messages - as I said - usually ver throw.

Discarding messages contained in the receive buffer is therefore carried out deliberately and is desirable because users signaling transport protocols generally none Use for incomplete received message sequences ha ben. This is only deviated from in rare special cases chen. So in the specification of the SSCOP for its ver application within the ITU-T signaling system number 7 Methods for correcting protocol errors disclosed in  accordingly - appropriate configuration of the protocol is required sets - when the protocol error occurs in reception messages contained in the buffer are not rejected, but the Be handed over to users. This is one for the user the largely transparent re-initialization of the faulty SSCOP connection coupled. For the treatment a permanent failure of the SSCOP connection this procedure to fix only temporary proto collisions not used in the prior art.

The invention has for its object the transmission of messages in cases where the transmission not or not completely, to improve. The on surrender is solved by the features of claim 1.

The essential aspect of the invention is that when messages are transmitted, each of which is assigned to one or more communication relationships and are transmitted via a common connection, the messages being transmitted to the respective recipients in the same order in which they are sent by the associated transmitters were originally sent, the messages are transmitted on the connection to secure the sequence marked with sequence numbers, at least one message is received out of the original sequence and is buffered in a receive buffer, the recipient likes to receive at least if the connection fails a message received out of order is enabled. Some essential advantages of the invention are mentioned below:

• - Messages are often sent to many people via a connection existing communication relationships at the same time wear. An example of this is the ITU-T signaling system stems number 7 with at least one connection - in this Context called "signaling route" - and in general several communication relationships - also "Signalisie relationship ". Hence the probability  low, that immediately consecutive Messages on a connection to the same communica relationship. Therefore, with high true Probability of incomplete receipt even when delivered Message sequences to the user only regarding egg of communication relationships actually have gaps in the associated news streams while the associated news streams of other communications relationships have no gaps and therefore lack can be further processed without any
• - From level 2 of the broadband time described at the beginning Chengabesystems are messages that are not in the required gapless order are received in Difference to level 2 of the narrowband signaling system not immediately rejected but in a reception puff fer cached. As a result of this spit cherns thus results in the broadband signaling system a connection to the switching procedure, since it differs to narrow band signaling system also received incompletely messages at the time of switching available. In the event of a defective order this message is not automatically discarded the number of rejected nights will be advantageous judge reduced and consequently the fulfillment of the ITU-T Standard Q.706 requirements regarding messages Loss of loss made easier
• - In combination with a TCP protocol, the through TCP protocol set increased due to message loss interpreted by the TCP protocol as an overload in the network becomes what with a lowering of the news broadcast rate is reacted
• - If the method according to the invention on a Radio connection is used, arise particularly nice advantages because on the one hand the in their transmission quality usually fluctuating radio connection quali tativ is secured and at the same time the interaction  the backup protocol with the throughput control of the TCP protocol is optimized

Further advantageous embodiments of the invention Procedures result from the subclaims.

For the exemplary embodiment, the broadband signaling system described at the beginning, in which level 2 is designed as an SSCOP, is assumed. In order to provide the improved service according to the invention in this signaling system, two prerequisites are necessary:
First, the SSCOP needs to be changed slightly. In principle, one change is that the receive buffer is not already emptied when the SSCOP connection is cleared down, but only when the SSCOP connection is re-established. Furthermore, a control must be created to control the delivery of the messages in the receive buffer to the user. These changes are completely transparent to the other party's SSCOP, so they can be introduced without any compatibility problems. They are also completely transparent for local applications that do not want to use the extended service.

Second, for applications that extend this Want to use service, specifications are made when or under what circumstances use of this new Services is opportune. For example, consider here tete application of network signaling using level 3 of Broadband signaling systems are available depending on this of the use case several forms, the following are listed as examples.

Specification 1 The local level 2 is without the support of Sequence number exchange implemented

With such an implementation, it is clear that Se sequence numbers are not sent out and therefore by the Ge Do not under any circumstances send messages that have already been sent alternative signaling routes or signaling routes such as be repeated. In this case either SSCOP for the Changed use in broadband signaling system that SSCOP connection failure generally means that the Receive buffer existing signaling messages to the To be handed over to the wender. Alternatively, the news transfer part to be expanded so that it immediately after delivery of the signaling route, the delivery of the Receive buffer requested by the (modified) SSCOP.

Specification 2 The removed level 2 is without support of sequence number exchange implemented

Should be known in a system - for example by correspondingly appropriate administrative advance that the other party never provides the sequence numbers, it is certain that Se sequence numbers are ignored there and therefore by the opposite do not put messages that have already been sent on al alternative signaling routes or signaling routes can be fetched. In this case, SSCOP can be used be changed in the broadband signaling system that in the case of SSCOP connection failure specifically identified drawn signaling routes generally those in the receive buffer transfer existing signaling messages to the user become. Alternatively, the message transfer part could go there be expanded so that it immediately after the failure of the Signaling route the delivery of the reception buffer from (modified) SSCOP required.

Specification 3 Both level 2 implementations supported zen principally the exchange of sequence numbers

There are several characteristic cases:  

Case 1: In situations where there is a specific failure locally the sequence number of the last accepted message is not available, the remote site can use this Fall messages already sent on alternate characters Do not repeat routes or signaling routes. If in this case the receive buffer is still available locally stands - which, however, would normally be unlikely may, the message transfer part can do so be confirmed that he immediately delivers the receiving buffer from the (modified) SSCOP.

Case 2: Depending on the implementation on the ent distant side it can in principle be the case that this remote site if they have no access in the event of a failure has the sequence number of the last accepted message, also no access to the messages in the transmission buffer Has. In this case, the local site can be obtained from the Emergency Changeover defined in the ITU-T standard Q.704 Message, which in this case is from the far side is sent, conclude that the removed page is already open of the failed signaling route on alternative signaling routes or signaling routes will not repeat. Here too the local news The transfer part can be expanded to include Receive an emergency changeover notification of delivery of the receive buffer from the (modified) SSCOP. The Information on which signaling routes are used may be, for example, by corresponding administrative Advance payments are made available.

Case 3: One side no longer has a possibility, the other the sequence number of the last accepted message notify because there are no available characters for it routes or signaling routes there, the distant Page already seen on the unusual signaling route messages on alternative signaling routes or Signaling routes not like because of the missing sequence number  derholen. The local message transfer section can also be used here be expanded to the extent that with appropriate Si tuation the delivery of the reception buffer from (mod SSCOP requires.

Case 4: The opposite party is informed that a new Sen already seen on the unusual signaling route alternate signaling routes or Signaling routes will not be possible. Receives the local Message transfer part the appropriate information, can he delivery of the reception buffer from the (modified) Request SSCOP. This solution has the advantage of being very fle to be xibel. For the transmission of the corresponding information There are basically two ways, one way back backward compatible and a non backward compatible.

With the backward-compatible path, a reserved bit is in the corresponding changeover messages. Imple mentions that do not include this improved service support, ignore this additional information without negative Impact.

In the non-backwards compatible way, new messages content in the corresponding changeover messages leads. To avoid negative effects in interaction with Im implementations that do not include this improved service support, avoid, for example, can correspond to appropriate administrative measures where this new method is used be drawn.

In conclusion, it should be noted that the pre proposed modification of the SSCOP as well as other protocols, what received messages cache, even if there are still gaps in the receive stream - e.g. B. certain expression HDLC (-like) protocols -, in addition to applications especially in network signaling everywhere  can be used advantageously where a delivery as possible al messages is more important than their complete delivery lung.

A nice example of another use case is in Find IP networks. The very common TCP protocol there, which are assigned to level 4 in the OSI shift model can carry out its own message backup, in which lost messages resent and exchanged messages straighten out properly. However, since the TCP protocol a loss of news, even if it is due to transmission errors occurred when congestion in the network ("Network Conges tion "), followed by its transmission rate transmission losses or losses, which are caused by route failure, negatively its throughput. Unless for qualitatively problematic Transmission lines - e.g. B. for error-prone radio link - Protocols with message backup (e.g. the proto SSCOP and / or HDLC) are used any failure of the transmission path according to the invention messages stored in the receive buffer are not rejected, but passed to the TCP / IP protocols for forwarding. Thus, the message loss for TCP connections, wel che use this transmission path, minimized and follow Throughput increased. This application can in particular a significant increase for IP transmissions via mobile phones throughput.

Claims (8)

1. Method for the transmission of messages which are each assigned to one of possibly several communication relationships and are transmitted via a common connection, the messages being transmitted to the respective recipients in the same order in which they were originally sent by the associated senders, in which

• - The messages are transmitted on the signaling connection for securing the sequence marked with sequence numbers,
• - At least one message is received out of the original order and is temporarily stored in a receive buffer, and
• - The receivers are able to receive at least one message received out of order if the connection fails.

2. The method according to claim 1, characterized, that the receive buffer even after the connection to least with the message received out of order remains filled. 3. The method according to claim 2, characterized, that the receive buffer is only emptied when the Ver bond is rebuilt. 4. The method according to any one of claims 1 to 3, characterized, that when the connection is cleared, the data stored in the receive buffer saved messages to the recipients.   5. The method according to any one of claims 1 to 3, characterized, that when the connection is cleared down by the receivers, the messages still stored in the receive buffer is required. 6. The method according to any one of the preceding claims, characterized, that the failure of the connection with the help of separate Messages is communicated. 7. The method according to any one of the preceding claims, characterized, that from at least one recipient the at least one except Consider the message received in order whether it is related to the assigned to the recipient Communication relationship transmitted in the correct order has been. 8. The method according to any one of the preceding claims, characterized, that the transmission of messages according to the ITU standard Q.2110 takes place.