CA2331706A1 - Method for signaling in a signaling transfer point - Google Patents
Method for signaling in a signaling transfer point Download PDFInfo
- Publication number
- CA2331706A1 CA2331706A1 CA002331706A CA2331706A CA2331706A1 CA 2331706 A1 CA2331706 A1 CA 2331706A1 CA 002331706 A CA002331706 A CA 002331706A CA 2331706 A CA2331706 A CA 2331706A CA 2331706 A1 CA2331706 A1 CA 2331706A1
- Authority
- CA
- Canada
- Prior art keywords
- signalling
- destination
- linkset
- messages
- loop
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q3/00—Selecting arrangements
- H04Q3/0016—Arrangements providing connection between exchanges
- H04Q3/0025—Provisions for signalling
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Data Exchanges In Wide-Area Networks (AREA)
- Computer And Data Communications (AREA)
- Maintenance And Management Of Digital Transmission (AREA)
Abstract
Routing loops may occur in signaling networks so that messages are routed to a destination in a loop without ever reaching said destination. The invention shows how such loops can be detected and eliminated as speedily as possible.
Description
METHOD FOR SIGNALLING IN A SIGNALLING TRANSFER POINT
It can occur in signalling networks according to signalling system No. 7 that routing loops occur in the network on MTP level 3 due to incorrect plamaing or operating errors, so that messages are routed to one or more destinations in a loop without ever reaching their destination. Of particular interest here are loops :having a length greater than 2 ("length of a loop" means the plurality of signalling points participating in a loop) and, in particular, how such loops can be eliminated when they are recognized.
If loops potentially present in the tables ~~re in fact used for routing, thus represents a serious problem for the network since rrtessages, on the one hand, do not arrive at their destination and, on the other hand, use valuable resources in the network. It should therefore be eliminated as fast as possible.
Loops having the length 2 (so-called ping-gong loops) cannot occur given a functioning protocol in the MTP (message transfer point). Should they nonetheless arise, these loops can be easily recognized in real time in a signalling transfer point in that a check is carried out to see whether a message i,s to be routed over the same linkset on which it was received. They are just as easy to correct in that the unsuccessful protocol actions (sending transfer prohiibited -- TFP -- messages to the cooperating party) are repeated.
It can occur in signalling networks according to signalling system No. 7 that routing loops occur in the network on MTP level 3 due to incorrect plamaing or operating errors, so that messages are routed to one or more destinations in a loop without ever reaching their destination. Of particular interest here are loops :having a length greater than 2 ("length of a loop" means the plurality of signalling points participating in a loop) and, in particular, how such loops can be eliminated when they are recognized.
If loops potentially present in the tables ~~re in fact used for routing, thus represents a serious problem for the network since rrtessages, on the one hand, do not arrive at their destination and, on the other hand, use valuable resources in the network. It should therefore be eliminated as fast as possible.
Loops having the length 2 (so-called ping-gong loops) cannot occur given a functioning protocol in the MTP (message transfer point). Should they nonetheless arise, these loops can be easily recognized in real time in a signalling transfer point in that a check is carried out to see whether a message i,s to be routed over the same linkset on which it was received. They are just as easy to correct in that the unsuccessful protocol actions (sending transfer prohiibited -- TFP -- messages to the cooperating party) are repeated.
2 0 Loops having a length >2 are more difficult to recognize. A check can in fact be performed with every message in a specific STP as to whether this message derives izom precisely this STP (by comparing the CiPC contained in the me:csage to the PointCode of the STP). When this is the case, there is a loop in the network.
STPs, however, do not necessarily generate messages or, respectively, do not;
2 5 necessarily generate messages to the destination or destinations to which there is a loop.
This problem can be solved by a real-time method that recognizes the possibility of a loop, for example due to a lasting overload on a linkset.
When said method recognizes the possibility of a loop, the operating personnel can be informed 3 0 so that corrective measures can be initiated.
The standard (Q.753, Q.754) defines another solution of the problem, what is referred to as the M~'F' route verification test (MRVT) that checks all possible paths in an MTP network between two given points for correctness, including freedom from loops. Upon occurrence of errors such as, for example, loops, the operating ;personnel is informed in order to undertake corrections. MRVT in fact has the advantage over a real-time method that it ~;.an also recognize loops bei:ore they are actually used, since all possible paths are checked, not only the current ones. The disadvantage, however, is that a separate protocol is required for it. When this is not realized in the entire network, the check is not possible or is only possible in incomplete form.
This l0 situation is specifically established in the international signalling network. I)ue to the load that it generates, moreover, the MRVT cannot constantly check all routes between all points in the network.
The invention is based on the object of overcoming the aforementioned disadvantages.
This object is achieved by a method according to claim 1.
The invention is explained in greater detail below with the assistance of the drawing, whereby the drawing comprises 3 Figures.
Figure 1 shows an example of a loop.
Figures 2 and 3 shows methods for parting a loop.
2 0 The present invention particularly reveals how, given real-time recognition of loops having a length > 2 and/or upon recognition of loops by the MRVT, the loops can be broken by automatic, real-time, protocol-compatible methods that are simple to realize. The time elapsing before the operating personal takes action can thus be bridged.
2 5 It must thereby be mentioned that it is advantageous, given possible loops that were recognized by the MRVT or a real-time method for a linkset, to check before having potential recourse to automatic correction measures (the MRV'T, namely, does not supply any statements whether a possible loop is also being employed at the time and, under certain circumstances, the real-time method cannot 3 0 make any statements about the destination to which a possible loop is present). Said check ensues by sending otherwise unemployed MT'P network management messages to the destinations that c;an be reached (according to the routing) via the appertaining linkset. When such test messages return to the STP, these messages are detf;cted by comparing the OPC contained in the message to the point code of the STP, and a loop or, respectively, several loops are recognized. Correction measures can thereby remain limited to loops being currently employed.
Said check vvith the assistance of test messages is already useful when it is realized in only one STP since all loops that run through this STP can be recognized.
The check method can also always be active.
Another possibility is comprised in making the initiation of correction 1 o measures dependent of the evaluation of the (relative) probability that the possible loop could be employed. These information can be made available by the M:RVT
in the form of priorities of the individual paths constituting the loop.
When a loop to a destination X is recognized in an STP A by the MRVT
or by real-time methods, one can proceed in the following way for breaking the loop:
a) Breaking the loop "downstream" in that the speciific departing path to this destination is blocked in the routing table in A. This step can, in particular, be implemented when other paths to X are also available proceeding from A. In this case, it is recommendable to also check the route employed as an alternative for the occurrence of a loop. Although the lack of a detection of a loop is no guarantee that 2 0 there is not some other loop that no longer contains A, there is at least a probability that the problem has been eliminated.
b) Alternatively, or if, fo:r example, there no longer happens to an alternate (loop-free) route proceeding from A, the loop can be broken "upstream", i.e. to the preceding STP B on the loop, in that A sends B a transfer prohibited message with respect to X.
2 5 In response thereto, B will reroute or, respectively, stop the traffic to X. Since B will subsequently periodically review the availability of the route to X via A with what are referred to as route set messages, it must be assured that A does not answer these messages with a transfer allowed, since B could otherwise re-close the loops.
After final correction of the routing tables by the operating persormel, the 3 0 actions automatically undlertaken by the MTP or the operations maintenance and administration part (OMAP) can be in turn reversed by the operating personnel (Note:
STPs, however, do not necessarily generate messages or, respectively, do not;
2 5 necessarily generate messages to the destination or destinations to which there is a loop.
This problem can be solved by a real-time method that recognizes the possibility of a loop, for example due to a lasting overload on a linkset.
When said method recognizes the possibility of a loop, the operating personnel can be informed 3 0 so that corrective measures can be initiated.
The standard (Q.753, Q.754) defines another solution of the problem, what is referred to as the M~'F' route verification test (MRVT) that checks all possible paths in an MTP network between two given points for correctness, including freedom from loops. Upon occurrence of errors such as, for example, loops, the operating ;personnel is informed in order to undertake corrections. MRVT in fact has the advantage over a real-time method that it ~;.an also recognize loops bei:ore they are actually used, since all possible paths are checked, not only the current ones. The disadvantage, however, is that a separate protocol is required for it. When this is not realized in the entire network, the check is not possible or is only possible in incomplete form.
This l0 situation is specifically established in the international signalling network. I)ue to the load that it generates, moreover, the MRVT cannot constantly check all routes between all points in the network.
The invention is based on the object of overcoming the aforementioned disadvantages.
This object is achieved by a method according to claim 1.
The invention is explained in greater detail below with the assistance of the drawing, whereby the drawing comprises 3 Figures.
Figure 1 shows an example of a loop.
Figures 2 and 3 shows methods for parting a loop.
2 0 The present invention particularly reveals how, given real-time recognition of loops having a length > 2 and/or upon recognition of loops by the MRVT, the loops can be broken by automatic, real-time, protocol-compatible methods that are simple to realize. The time elapsing before the operating personal takes action can thus be bridged.
2 5 It must thereby be mentioned that it is advantageous, given possible loops that were recognized by the MRVT or a real-time method for a linkset, to check before having potential recourse to automatic correction measures (the MRV'T, namely, does not supply any statements whether a possible loop is also being employed at the time and, under certain circumstances, the real-time method cannot 3 0 make any statements about the destination to which a possible loop is present). Said check ensues by sending otherwise unemployed MT'P network management messages to the destinations that c;an be reached (according to the routing) via the appertaining linkset. When such test messages return to the STP, these messages are detf;cted by comparing the OPC contained in the message to the point code of the STP, and a loop or, respectively, several loops are recognized. Correction measures can thereby remain limited to loops being currently employed.
Said check vvith the assistance of test messages is already useful when it is realized in only one STP since all loops that run through this STP can be recognized.
The check method can also always be active.
Another possibility is comprised in making the initiation of correction 1 o measures dependent of the evaluation of the (relative) probability that the possible loop could be employed. These information can be made available by the M:RVT
in the form of priorities of the individual paths constituting the loop.
When a loop to a destination X is recognized in an STP A by the MRVT
or by real-time methods, one can proceed in the following way for breaking the loop:
a) Breaking the loop "downstream" in that the speciific departing path to this destination is blocked in the routing table in A. This step can, in particular, be implemented when other paths to X are also available proceeding from A. In this case, it is recommendable to also check the route employed as an alternative for the occurrence of a loop. Although the lack of a detection of a loop is no guarantee that 2 0 there is not some other loop that no longer contains A, there is at least a probability that the problem has been eliminated.
b) Alternatively, or if, fo:r example, there no longer happens to an alternate (loop-free) route proceeding from A, the loop can be broken "upstream", i.e. to the preceding STP B on the loop, in that A sends B a transfer prohibited message with respect to X.
2 5 In response thereto, B will reroute or, respectively, stop the traffic to X. Since B will subsequently periodically review the availability of the route to X via A with what are referred to as route set messages, it must be assured that A does not answer these messages with a transfer allowed, since B could otherwise re-close the loops.
After final correction of the routing tables by the operating persormel, the 3 0 actions automatically undlertaken by the MTP or the operations maintenance and administration part (OMAP) can be in turn reversed by the operating personnel (Note:
OMAP comprises higher-ranking SS7 management functions, for example MRVT, screening functions and measurements. "Informing the operating personnel" is also (partially) part of the OMAP) A special characteristic of the invention is comprised in the mechanism for breaking loops having the length > 2 with automatic measures that are simple to realize upon utilization of existing protocol features. In particular, the method can already be employed and is useful when it is realized in only a single STP.
One possibility for realizing the alternative b) is to automatically activate what is referred to as ILS/DPC screening (ILS = incoming linkset; see Q.705, ~8) in A for messages from ~ to X. However, a linking of the ILS/DPC screening into the MTP management network is needed for this purpose such that an illegal message is answered with a TFP message and the route set test messages are also correctly handled.
One possibility for realizing the alternative b) is to automatically activate what is referred to as ILS/DPC screening (ILS = incoming linkset; see Q.705, ~8) in A for messages from ~ to X. However, a linking of the ILS/DPC screening into the MTP management network is needed for this purpose such that an illegal message is answered with a TFP message and the route set test messages are also correctly handled.
Claims (9)
1. Method for the signalling in a signalling transfer point, in accord wherewith -- signalling messages stemming from source signalling points are routed in the direction toward destination signalling points, -- the presence of a loop or, respectively, the possibility of the presence of a loop over a departing linkset to a destination signalling point (SP X) is checked by a routing test (MRVT) and/or by a real-time method, -- given a positive check result, signalling messages are automatically prevented from continuing to be sent to the destination signalling point (SP X) via the appertaining linkset.
2. Method according to claim 1, characterized in that -- given said positive check result, test messages are first sent via a linkset to destinations that can be reached via said linkset;
-- in the case of returning test messages, signalling messages are then automatically prevented from being sent to a destination that had returning test messages.
-- in the case of returning test messages, signalling messages are then automatically prevented from being sent to a destination that had returning test messages.
3. method according to claim 1 or 2, characterized in that signalling messages are prevented (downstream) from being sent to the appertaining destination via the appertaining linkset in that the specific, departing linkset to this destination is blocked in the routing table of the signalling transfer point.
4. Method according to claim 1 or 2, characterized in that signalling messages are prevented (upstream) from being sent to the appertaining destination via the appertaining linkset in that the signalling transfer point (STP A) sends a transfer prohibited message regarding the destination signalling point (SP X) to the preceding signalling transfer point (STP B), whereupon the preceding signalling transfer point (STP B) will reroute or, respectively, stop the traffic to the destination signalling point (SP X).
5. Method according to one of the claims 1 through 4, characterized in that said interruption of the loop is controlled by the operations maintenance and administration part (OMAP).
6. Method according to one of the claims 1 through 5, characterized in that said interruption of the loop is controlled by the message transfer part (MTO).
7. Method according to one of the claims 1 through 6, characterized in that, after blocking the linkset contained in the loop, the new, current route is in turn immediately checked for freedom from loops in the signalling transfer point (STP A).
8. Signalling system of a signalling transfer point that routes signalling messages to destination signalling points, characterized in that -- it checks the presence of a loop or, respectively, the possibility of the presence of a loop over a departing linkset to a destination signaling point (SP X) by a routing test (MRVT) and/or by a real-time method, whereby -- when a positive check result is obtained, signalling messages are automatically prevented from continuing to be sent to the destination signalling point via the appertaining linkset.
9. Signalling system of a signalling transfer point according to claim 8, characterized in that it verifies the detected possibility of the presence of a loop by sending test messages to destinations reachable via said linkset before it automatically prevents signalling messages from continuing to be cent via the appertaining linkset to a destination for which said test messages return.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP98108645.7 | 1998-05-12 | ||
| EP98108645 | 1998-05-12 | ||
| PCT/EP1999/003048 WO1999059349A1 (en) | 1998-05-12 | 1999-05-04 | Method for signaling in a signaling transfer point |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2331706A1 true CA2331706A1 (en) | 1999-11-18 |
Family
ID=8231919
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002331706A Abandoned CA2331706A1 (en) | 1998-05-12 | 1999-05-04 | Method for signaling in a signaling transfer point |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP1078536A1 (en) |
| CN (1) | CN1300507A (en) |
| CA (1) | CA2331706A1 (en) |
| WO (1) | WO1999059349A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101155062B (en) * | 2006-09-30 | 2012-10-03 | 华为技术有限公司 | Method, device and system for settling exception of signaling network |
| CN100579077C (en) * | 2007-03-22 | 2010-01-06 | 华为技术有限公司 | Routing method and system under double-signalling switching point and mutual supporting network element group network |
| CN102164055A (en) * | 2011-02-23 | 2011-08-24 | 华为技术有限公司 | Detection processing method and device for signaling connection control part (SCCP) loop |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5583848A (en) * | 1994-11-15 | 1996-12-10 | Telefonaktiebolaget L M Ericsson | Methods for verification of routing table information |
| US5553058A (en) * | 1995-07-10 | 1996-09-03 | Telefonaktiebolaget Lm Ericsson | Centralized load minimizing method for periodical routing verification tests scheduling |
| US5638357A (en) * | 1995-08-25 | 1997-06-10 | Telefonaktiebolaget Lm Ericsson (Publ) | Distributed method for periodical routing verification test scheduling |
-
1999
- 1999-05-04 WO PCT/EP1999/003048 patent/WO1999059349A1/en not_active Application Discontinuation
- 1999-05-04 EP EP99920848A patent/EP1078536A1/en not_active Withdrawn
- 1999-05-04 CN CN 99806124 patent/CN1300507A/en active Pending
- 1999-05-04 CA CA002331706A patent/CA2331706A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP1078536A1 (en) | 2001-02-28 |
| CN1300507A (en) | 2001-06-20 |
| WO1999059349A1 (en) | 1999-11-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP2361468B1 (en) | Congestion control method and devices | |
| US7768917B2 (en) | Congestion control system, congestion control method, congestion control program, and program recording medium | |
| US6996225B1 (en) | Arrangement for controlling congestion in an SS7 signaling node based on packet classification | |
| US7088728B2 (en) | Methods and systems for routing signalong messages to the same destination over different routes using message origination information associated with non-adjacent signaling nodes | |
| US7466815B2 (en) | Methods and systems for detecting and preventing signaling connection control part (SCCP) looping | |
| CN101132313B (en) | Routing failure recovery mechanism for network systems | |
| US8189625B2 (en) | Method for clock link automatic protection in packet transport networks | |
| US8903074B2 (en) | Methods, systems, and computer program products for congestion-based routing of telecommunications signaling messages | |
| PL183244B1 (en) | System and apparatus for and method of effecting telecommunication signalling using an improved signalling station | |
| US20060187841A1 (en) | Methods, systems, and computer program products for suppressing congestion control at a signaling system 7 network node | |
| US5930236A (en) | Method for preventing circular routing in a telecommunication network | |
| US20070217391A1 (en) | Methods, systems, and computer program products for setting congestion levels for a plurality of routes to a common destination | |
| US8135116B2 (en) | Methods, systems, and computer program products for managing traffic congestion in a network through detection of a source of excessive call volume | |
| US6747955B1 (en) | Method and system for congestion control in a telecommunications network | |
| CA2331706A1 (en) | Method for signaling in a signaling transfer point | |
| US7023977B2 (en) | Method and system for providing softswitch failure protection in a communication network | |
| US20070286083A1 (en) | Methods, systems and computer program products for individually identifying and disabling circular routes from a plurality of active routes to a common destination | |
| US7065200B2 (en) | Method of detecting circular routing in No. 7 signaling | |
| US8218740B2 (en) | Method for providing hysteresis to fluctuating signaling ink | |
| CN113543138B (en) | Abnormal telephone interception system, method and storage medium | |
| JPH09107402A (en) | Method and communication network for multiplex call control | |
| KR100350314B1 (en) | Method For Processing In Case Of Routing Failure Of Signal Message In A No.7 Signalling Network | |
| US8130933B2 (en) | Method for recovery from linkset failure in telecommunications network | |
| JPH10210149A (en) | Method, exchange and communication network to control setup of connection to subscriber, destination of mass calling | |
| EP1241899B1 (en) | Method for preventing circular routing in a switched telephone network |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |