WO2006111182A1 - Procede et systeme de resolution des etats de concurrence dans un reseau de communication - Google Patents

Procede et systeme de resolution des etats de concurrence dans un reseau de communication Download PDF

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Publication number
WO2006111182A1
WO2006111182A1 PCT/EP2005/004257 EP2005004257W WO2006111182A1 WO 2006111182 A1 WO2006111182 A1 WO 2006111182A1 EP 2005004257 W EP2005004257 W EP 2005004257W WO 2006111182 A1 WO2006111182 A1 WO 2006111182A1
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WO
WIPO (PCT)
Prior art keywords
session
race condition
session manager
control sequence
solving
Prior art date
Application number
PCT/EP2005/004257
Other languages
English (en)
Inventor
Hugo Zwaal
Rakesh Taori
Original Assignee
Telefonaktiebolaget Lm Ericsson (Publ)
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget Lm Ericsson (Publ) filed Critical Telefonaktiebolaget Lm Ericsson (Publ)
Priority to PCT/EP2005/004257 priority Critical patent/WO2006111182A1/fr
Publication of WO2006111182A1 publication Critical patent/WO2006111182A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/16—Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
    • H04L69/163—In-band adaptation of TCP data exchange; In-band control procedures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/30—Definitions, standards or architectural aspects of layered protocol stacks
    • H04L69/32—Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
    • H04L69/322—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions
    • H04L69/329—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions in the application layer [OSI layer 7]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/40—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection

Definitions

  • the present invention relates generally to communications systems, comprising mobile communication terminals and a radio network infrastructure, fixed communication terminals, application nodes and a fixed land based transport network. More particularly, the present invention facilitates a method and system for handling race conditions in IP based communications in such systems.
  • Communication can be of a direct type, like video or voice, but can also be of an indirect type where a user of a communication terminal interacts with a running application on his/hers terminal (client) that communicates with another client or an application running on a node (server) in the communications system.
  • client his/hers terminal
  • server node
  • the communications system may also contain nodes that are not capable of running applications, in the content of the present invention the term Node shall further mean a node that has the capabilities of running applications that communicate with other applications.
  • Access can be based on a radio link such as generally known under the acronyms WLAN, GPRS, UMTS, or Bluetooth, or on a fixed line link like ADSL, SDSL, cable-modem, LAN, ISDN or regular PSTN, or on other types of access technology like InfraRed ports.
  • Communication terminals not having fixed line access possibilities are identified as mobile terminals.
  • Communication terminals having fixed line access possibilities or a combination of fixed and radio based access are further identified as fixed terminals.
  • Terminal (s) is equally valid for mobile and fixed communication terminals.
  • Examples of handovers are: a fixed terminal switches from a cable modem to an ISDN link due to a slow response on the cable modem access, or a mobile terminal switches from GPRS to a less expensive WLAN connection when in reach of a WLAN access point.
  • a session manager controls activities performed in the session layer and hence also reconnection in case of handovers.
  • the session manager of one Terminal may act as the initiating party.
  • the session managers of both communication Terminals initiate a handover simultaneously, like when a link fails. In that case a problem exists, as both session managers may initiate not the same alternative link. Both sides may inform the other of the alternative, but it does not solve the problem, as both session managers have their own link and the link selected by the other.
  • a race condition can also occur when communication is started.
  • a source session manager will initiate creation of a session at a destination by sending an establish session message to the session manger at the destination.
  • the session manager receives an information packet from the application before such an establish session message has been received, this will initiate a session towards the source session manager.
  • both session managers will end up with two sessions in their administration for only one active session.
  • race condition is solved by exchanging information between parties involved. This takes several communication steps in which information messages are exchanged.
  • Another known solution is awareness of environment and use of environmental variables to solve the race condition independently of another party.
  • the second mentioned known solution does not have these problems, but introduces a new problem in that the session manager must be aware of the environment it works in.
  • the session manager is, however, intended to be a single version function whether in a mobile terminal, a fixed terminal or a node in the communications system. No single mechanism is possible that can be used in .all types of Nodes and Terminals, therefore this solution is also not acceptable. Summary of the invention
  • the problem to be solved by the present invention is to allow session managers to solve race conditions without the need for additional communication, and unaware of the environment they are in.
  • the present invention provides a method for solving a race condition between a first and a second control sequence running simultaneously during session control in a communications system.
  • the system comprises an interconnecting network, one or more mobile or fixed terminals and one or more application nodes, wherein the or each terminal and the or each application node are operatively connected to the interconnecting network and each comprise a session manager for controlling sessions.
  • a first session manager through said first control sequence, controls a first session that communicates with a second session controlled by a second session manager through said second control sequence.
  • the method is characterized by the steps of: - detecting a race condition by the first and second session manager, and - discarding one and the same control sequence by the first and second session manager independently, based on control information exchanged between the first and second session manager prior to the detection of the race condition.
  • a race condition detection and solver function is incorporated into the session manager.
  • This race condition detection and solver function solves race conditions based on characteristics of information packets already received from another session manager in the normal control of sessions.
  • both session managers can independently detect and solve a race condition unaware of their environment, without additional communication with the other session manager, merely based on information already received by a session manager.
  • control information for discarding a control sequence is comprised by an IP address associated with this control sequence.
  • IP addresses for selecting a control sequence to be discarded by the session managers involved is applicable to all types of session managers and is applicable for solving several kinds of race conditions that can occur in an IP based network.
  • the control sequence to be discarded may be the control sequence discarded having the highest or lowest IP address, for example. That is, highest or lowest seen in a mathematical or numerical ranking.
  • the control sequence to be discarded may be selected on the basis of an IP address extended by at least one of a session number and a port number.
  • the invention further relates to a session manager device, comprising race condition solving function means arranged for operating in accordance with the method of the invention as disclosed above, a mobile communication terminal, a fixed communication terminal and an application Node comprising such a session manager device.
  • the invention also relates to a communications system comprising an interconnecting network, at least one mobile communication terminal and/or at least one fixed communication terminal and/or at least one application node as disclosed above, operatively connected to the interconnecting network.
  • Figure 1 shows a schematic diagram of entities involved in controlling a session layer
  • Figure 2a shows a schematic diagram of communication steps by the entities of figure 1, in the case of starting a session without a race condition
  • Figure 2b shows a prior art schematic diagram of communication steps by the entities of figure 1, in the case of a session involving a race condition
  • Figure 2c shows a solution for solving a race condition of figure 2b in accordance with the present invention
  • Figure 3a shows a schematic diagram of communication steps by the entities of figure 1, in case of handing over a session without a race condition
  • Figure 3b shows a schematic diagram of communication steps by the entities of figure 1, in case of handing over a session involving a race condition, and
  • Figure 3c shows a solution for solving a race condition of figure 3b in accordance with the present invention.
  • Figure 1 shows a communications system involving Terminals and/or Nodes as outlined above in the background description.
  • handovers between Terminals or Nodes Ia, Ib need to be performed seamlessly without disturbing communication of running applications. It is therefore required that a running instance (a session) of an application 2a, 2b in the application layer of the Terminal or Node Ia, Ib is instantaneously reconnected via another access type provided by the lower control layers. This connection of access type and session is provided in a session layer 6.
  • a session manager 3a, 3b of a Terminal or Node Ia, Ib controls activities performed in the session layer 6 and hence also reconnection in case of handovers.
  • Each session manager 3a, 3b comprises a communication monitoring function 4a, 4b and a session administration function 5a, 5b.
  • An example of a monitoring function is called TESLA.
  • An example of a session administration function is called Migrate, which runs as a daemon in a Terminal or Node.
  • the communication monitoring function 4a, 4b provides a copy of packets sent by the running instance of an application 2a.
  • this copy comprises an IP address of a destination Terminal or Node Ib, a port number of the destination application 2b, a source IP address and a port number used by the application 2a.
  • the combination of port number and IP address is known as socket address, and will be used from here on.
  • the copy of the packets is received by the session administration function 5a, 5b.
  • the session administration functions 5a, 5b exchange messages for controlling the administration of sessions.
  • the messages are exchanged via a control channel 8 between the sessions administration functions 5a, 5b.
  • the communication between the applications 2a, 2b takes place over a data channel 9.
  • Both the data channel 9 and the control channel 8 may use the same link 7 and may have identical IP addresses but different port numbers.
  • first application 2a in a first Terminal or Node Ia When an instance of a first application 2a in a first Terminal or Node Ia starts communication, it will send a first packet to a second application 2b in a second Terminal or Node Ib.
  • the monitoring function 4a In the first Terminal or Node Ia, the monitoring function 4a will copy the packet and forward same to its session administration function 5a.
  • This first session administration function 5a prepares a control channel 8 to its counter part, i.e. a second session administration function 5b in the second Node or Terminal Ib of the second application 2b.
  • the first session administration function 5a starts by sending a TCP/IP-SYN connect packet 11a to the second session administration function 5b.
  • the second administration function 5b sends a TCP/IP-SYN/ACK accept packet 12a to the first session administration function 5a.
  • the first session administration function 5a sends a TCP/IP-ACK acknowledge packet 13a in return.
  • the control channel 8 between both session administration functions 5a, 5b is now established.
  • the first session administration function 5a then creates a communication session in its administration, comprising information on its own first socket address and first session number for the first application 2a. It sends an establish message 21a containing a first IP address and the assigned session number to the second administration function 5b via the established control channel 8.
  • the second administration function 5b has prepared its session in its administration comprising a second socket address and a second session number for the second application 2b.
  • the second session administration function 5b replies to the first session administration function 5a with an established message 22a containing the second session number and a second IP address.
  • the first administration function 5a sends a connection message 23a comprising first and second socket address.
  • the second administration function 5b replies with a session message 24a comprising the first and second socket address as well as the first and second session number.
  • first 2a and second applications 2b are communicating. For some reason a handover to another type of access takes place, so a new link is to be established for further communication.
  • the first session administration function 5a prepares a control channel 8 to the second session administration function 5b via the new link, as outlined in figure 3a part A.
  • the first session administration function 5a starts by sending a TCP/IP-SYN connect packet 11a to the second session administration function 5b.
  • the second administration function 5b sends a TCP/IP-SYN/ACK accept packet 12a to the first session administration function 5a.
  • the first session administration function 5a sends a TCP/IP-ACK acknowledge packet 13a in return.
  • the control channel 8 between both session administration functions 5a, 5b via the new link is now established.
  • the second session administration function returns a challenge message 32a to check authentication for allowing handover.
  • the first session administration function replies with a response message 33a. See part B of figure 3a.
  • the second session administration function 5b now sets-up a data channel 9 via the new link, referenced by C in figure 3a, by sending a TCP/IP-SYN connect packet 15a to the first session administration function. It replies with a TCP/IP-SYN/ACK accept packet 16a.
  • the set-up of the data channel 9 is completed with the return of a TCP/IP-ACK acknowledge packet 17a to the first session administration function 5a.
  • the handover is completed with both session administration functions 5a, 5b exchanging packet sequence numbers as valid for the data channel in the' old link. Both session administration functions 5a, 5b then independently exchange the data channel over the old link with the data channel over the new link, when all packets are received and acknowledged.
  • the old data channels are closed with a TCP/IP-RST close packet (not shown) .
  • the second session administration function 5b also starts a sequence of packets as indicated by the dotted arrows and referenced with identifiers having suffix b, in figure 3b part A. Both set-up a control channel 8 via the new link and send a migrate message 31a, 31b. When both have received their migrate message the race condition 99 is evident, as both require taking the same socket address to migrate to.
  • the race condition detection and solver function 10a, 10b provided in the session managers 3a, 3b, respectively, detects a race condition and solves it before further communication between both session administration functions 5a, 5b takes place.
  • the race condition detection and solver function 10a, 10b in accordance with the present invention operates in three steps.
  • the race condition detection and solver function 10a, 10b for both session administration functions 5a, 5b uses the last received IP address in messages received, to mark either the a-sequence or the b-sequence to be stopped or discarded.
  • IP addresses are bound to be different and unique, the condition of the higher IP or lower IP address, seen in mathematical or numerical ranking order, may be advantageously used for marking one of them of the control sequence to be stopped or discarded. This, to the choice of a network operator, for example.
  • Both race condition detection and solver functions 10a, 10b independently take its decision in either stopping its own initiated control sequence or the control sequence initiated by the other, as result of different IP addresses, while using the same decision algorithm.
  • IP addresses can be extended with session numbers, port number or other elements to obtain additional advantages.
  • the method selected must, however, be identical throughout all implementations of the race solver function in network nodes and terminals.
  • both session administration functions 5a, 5b handle the stopping of one sequence where as the other sequence continues as if there was no race condition.
  • the stopping activities may differ depending on whether the race condition originates from a migrate message 31a, 31b or a connection message 11a, lib.
  • the session administration function that initiated the control channel 8 for the sequence to be stopped here the b-sequence, is to be aborted, as is shown, and closes the channel with a TCP/IP-RST close packet 14b.
  • connection message 11a, lib referring to figure 2c, the session administration function that initiated the control channel 8 for the sequence to be stopped, here the a-sequence, is to be aborted, as is shown, and likewise closes the channel with a TCP/IP-RST close packet 14a.
  • both sides discard the session created in the a-sequence.
  • the described race condition solving during handover is an example given for the TESLA and Migrate equipped session manager.
  • the method of using IP addresses already received, for selecting one out of two options is, however, applicable to all types of session managers. It provides a method in which both sides take independently a solution for stopping or discarding one of the control sessions and to continue the other control session, unaware of environmental characteristics, without additional communication and based on the same algorithm. For these reasons, it is an ideal method for solving all kinds of other race conditions that can occur in an IP based network.
  • race condition detection and solver function in accordance with the present invention, may be implemented as a hardware and/or software function means 10a, 10b in a session manager device 3a, 3b of a communication Terminal or Node Ia, Ib operatively connected to a communications network 7, 8, 9.
  • race condition detection and solver function 10a, 10b may also be implemented in the session administration function 5a, 5b as a hardware and/or software implemented function means, as schematically indicated in figure 1 by dotted lines. It is also feasible to partly implement the race condition detection and solver function in the session manager device 3a, 3b and partly in the session administration function 5a, 5b, for example. Further, the race condition detection and solver function 10a, 10b may also be implemented in the communication monitoring function 4a, 4b (not shown).

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  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention porte sur un procédé et un système de résolution des états de concurrence dans un contrôle de session, dans un système de communication, possédant des terminaux mobiles, des terminaux fixes et des noeuds d'application. Chaque terminal ou noeud (1a, 1b) présente au moins un gestionnaire de session (3a, 3b) et un état de détection de concurrence ainsi qu'une fonction de résolution (10a, 10b). La détection d'état de concurrence et la fonction de résolution (10a, 10b) suppriment une des séquences impliquées dans un état de concurrence, en fonction des informations de contrôle échangées entre les gestionnaires de session (3a, 3b) des terminaux ou noeuds de communication (1a, 1b), telle une adresse IP.
PCT/EP2005/004257 2005-04-18 2005-04-18 Procede et systeme de resolution des etats de concurrence dans un reseau de communication WO2006111182A1 (fr)

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PCT/EP2005/004257 WO2006111182A1 (fr) 2005-04-18 2005-04-18 Procede et systeme de resolution des etats de concurrence dans un reseau de communication

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130080632A1 (en) * 2007-09-20 2013-03-28 Microsoft Corporation Crisscross cancellation protocol
US11909054B2 (en) 2019-08-06 2024-02-20 Btl Advanced Material Co. Ltd. Aluminum pouch film for secondary battery, and manufacturing method therefor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
D. BRYANT: "DLSw v2.0 Enhancements", IETF RFC2166, - 30 June 1997 (1997-06-30), XP002362021, Retrieved from the Internet <URL:http://www.javvin.com/protocol/rfc2166.pdf> *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130080632A1 (en) * 2007-09-20 2013-03-28 Microsoft Corporation Crisscross cancellation protocol
US9015349B2 (en) * 2007-09-20 2015-04-21 Microsoft Technology Licensing, Llc Crisscross cancellation protocol
US9219673B2 (en) 2007-09-20 2015-12-22 Microsoft Technology Licensing, Llc Crisscross cancellation protocol
US9686320B2 (en) 2007-09-20 2017-06-20 Microsoft Technology Licensing, Llc Crisscross cancellation protocol
US11909054B2 (en) 2019-08-06 2024-02-20 Btl Advanced Material Co. Ltd. Aluminum pouch film for secondary battery, and manufacturing method therefor

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