Data communications system with session control

The invention relates to data communication systems, a session control between a group of Benut zerendeinrichtungen that with over shared channels one or more host computers communicate, have.

Data communication systems deliver fixed or wireless two routes data communications, which users, as example as professionals, allow almost immediately with Business colleagues, clients, family members and friends to commu cate. A typical wireless data communication system includes user terminals, network gateways, network controllers and base stations. A typical base station covers a small area with a radius of a few kilome tern and forms a data communication system with Benut zerendeinrichtungen. A network controller controls typi cally the communications of an area which a lot covers number of base stations. A host computer is in the generally installed by the user and performs ver different applications.

Data communication systems for wireless electronic Mail (e-mail) and data transfer, news queries and enhanced information services used. There may be additional to application to be developed, the users a wireless Access to shared and public information systems allow.

Today can be accessed accurately to information, when and where it is needed, and it can time-bound to send and receive messages wherever also the User goes. However, when a host computer fails, , the data communication system messages from the User terminals for problematic host computer supply. This allows the data communication network performance be adversely affected. If the affected appli vide more information from the user terminals to the proble Send matic host computer, then all users (Including those that are not problematic with the Host computer are connected) longer Nachrichtenübertra Watch movement times.

Network performance can also be adversely affected by the host computer be affected, which slowly to messages by Be Users your directions are sent, respond. As in Host computers that have failed, all users Watch a deteriorated performance, even when they another group of user terminals belong.

It may further clogging occur if Nachrich th critical resources, such as a buffer region, exhaust. A buffer area is an area of ​​memory allocated for buffer purposes. In Datenkommunikationsnet zen can füh failed or slow host computer to ren that they post messages on the interfaces between the stop network components.

The US 4,975,914 describes a the preamble of claim 1 corresponding method for recovery a session without interruptions in a Communication system, comprising a plurality of host systems includes each of meetings with various other devices communicate over different connections. Two counters are set, the first to set the interval, during the meeting about the current connection can be taken up and a second counter for While the attempts made setting a maximum time be to find an alternative connection.

It is therefore the object of the invention to provide an improved A method for managing meetings and Performing an end-to-end session control in a indicate data communication system. It would be desirable be to protect the data communication network in situations where failures that a specific host computer concern, not all user terminals and their Users compromise.

is this object and by the method according to claim 1 the system dissolved claim 5. Preferred Embodiments are subject of the subclaims.

First, the acronyms are explained briefly below:DTE: Data Terminal HUM: host user directoryNAK-SDU: negative acknowledgment - Service Data UnitRD-LAP: radio data link access protocolRNC: Radio Network ControllerRNG: radio network gatewayRPM: radio packet modemSDU: Service Data Unit

This invention has many embodiments and advantages, which the following aspects in no way eingrenzender including KISSING. There is provided a data communication system, the a data communications network, at least one first host Computer and a group of at least two user Your directions comprises. At least the first host computer is connected to the data communication network connected. The group of minde least two user terminals (eg Funkda requested your directions) are at least to the first Host computer via the data communications network in conjunction.

The data communications network comprises a RNG, a buffer, ei NEN error detector, an instruction generator, a data base, a RNC and at least one base station. The buffer spei chert temporarily messages from the user Your direction to the host computer and from the latter to the Benut zerendeinrichtung be sent. The error detector is with connected to the data communication network, a bug in egg ner communication with at least the first host computer to identify. The command generator is responsive to the error detector for generating a session control instruction, and Send the session control command to the group of least two user terminals. identifies the data base Relations between the group of at least two Benut zerendeinrichtungen and at least the first host computer. This relationship is for selecting the group of Benut zerendeinrichtungen in communication with at least the first Host computer is desirable. At least the first host Compu ter is connected to the command generator to the Befehlsge generator to cause it to generate session commands, that is specific to a group of Benutzerendeinrichtun gen relate that be of at least the first host computer be influenced.

In a preferred embodiment of the invention comprises Database host user directories that communication the tion meetings between the group of Benutzerendeinrichtun identify gene and the at least first host computer. The host user directories allow the command Gene generator, the session control command to each user Your Rich sending device to identifi the communication session ren. Each user terminal has devices for the Receiving the session control command for comparing the received session identifier with a Sitzungsidenti fizierer which is stored in the user terminal, and for executing a session control action when a Match exists. Instead of storing the host-Be user directory table in the database, other on Regulations are used to veran the command generator blank, a session control command to the group of Benut zerendeinrichtungen to send (as detailed below discusses lines).

In an alternative embodiment, the RNC or intercepts other network device subsequent messages (the egg ner session control action follow), of a user terminal device are transmitted to a host computer. Be Preferred embodiments of the invention are exemplified described with reference to the drawings.

Other advantages and features of the invention will be described with reference <b>2</b> described on preferred embodiments, the inventions the tion represent but they are not intended to limit.

<b>Fig.</b> 1 is a general embodiment of the invention, the a method for operating a data communication system shows;

<b>Fig.</b> 2 is a block diagram showing the Datenkommunikationssy system according to a preferred embodiment of the invention shows;

<b>Fig.</b> 3 is an example of a host-user directory, the RNG in the <b>Fig.</b> 2 is maintained;

<b>Fig.</b> 4 is an illustration of the format of an SDU for Sit use management data;

<b>Fig.</b> 5 is an illustration of a protocol stack of the Sy stems of <b>Fig.</b> 2, in particular for representation of a new session manager is used;

<b>Fig.</b> 6 is a diagram of the signaling between ver different elements of the data communication system of the <b>Fig.</b> 2 according to the preferred embodiment of the invention;

<b>Fig.</b> 7 is a detailed flowchart of the implementation the user terminal-to-host computer session control according to the preferred embodiment of the invention;

<b>Fig.</b> 8 is a diagram of the signaling between ver various elements of the system of <b>Fig.</b> 2, according to an al alternatives embodiment of the invention;

<b>Fig.</b> 9 is a detailed flowchart of the implementation the user terminal-to-host computer session control according to an alternative embodiment of the invention; and

<b>Fig.</b> 10 is a flowchart of a session control according to another aspect of the invention.

<b>Fig.</b> 1 is a generalized embodiment of the inventions tion, a method of operating a Datenkommunika tion system <b>5</b> represents. The data communication system<b>5</b> around summarizes a data communication network <b>10</b> and at least one first communication device <b>1</b>, A second communication tion device <b>2</b> and a third communication device <b>3</b> in communication with the data communication network <b>10</b>, Each Communication device comprises a session manager <b>11</b>,

In operation, the data communication network identified <b>10</b> an error status change in the communication with the first Communication device. A network device<b>9</b> Since the tenkommunikationsnetzwerkes <b>10</b> generates a session control command <b>6</b> in response to the identification of the change the error Statuses. The session control command generated<b>6</b> around summarizes an identification number <b>7</b>, The identification number may be the following but not limited to: a Be user identification number, a Sitzungsidentifikationsnum mer, a connection identification number, a host route Communication identification number, a Anschlußidentifika tion number, a Endeinrichtungsidentifikationsnummer, a Host user directory identification number or a Mo demidentifikationsnummer. The network device<b>9</b> Since the tenkommunikationsnetzes <b>10</b> sends the session control command at least the second and third Kommunikationsvorrich tions <b>2</b> and <b>3</b>Either by an individual addressing the message to each of the affected Kommunikationsvorrich tions or preferably by addressing a single Transmission message to e ine variety of Kommunikationsvor directions. Alternatively, another Gruppenkommunika tion mechanism be used. Each of the second and DRIT th communication devices <b>2</b> or 3 receives the session control command <b>6</b>, Determined from the identification number <b>7</b>Whether the respective communication device by the change in the error Statuses is concerned, and leads in Response, selected from a session control action. The session control action may not limited to, for example, the interruption of transmission to min least one identified target for at least one time period, erasing an earlier session control action or the resetting of the session control actions include.

Referring to <b>Fig.</b> 2, there is shown the Datenkommunika tion system <b>5</b> according to a preferred embodiment of the invention shown. The data communication system<b>5</b> includes Data communication network <b>10</b>, At least the first host computer <b>12</b> and the group of at least two user terminals facilities <b>14</b> and <b>15</b>, The data communication network<b>10</b> includes the RNG <b>20</b>, The RNC <b>30</b> and at least one base sta- tion <b>32</b> (But typically many base stations). A case play an appropriate base station is a Datensystemsta tion-II (DSS-II), which is available from Motorola, Inc.. The RNG further comprises the following components: a buffer <b>22</b>. an error detector <b>24</b>, A command generator <b>26</b> and a data base <b>28</b>, Each user terminal<b>14</b> includes a receiver <b>13</b>, An RPM <b>16</b> or other suitable modem, a Nachrichtendekodierer <b>17</b> and a DTE <b>18</b> (example , a laptop computer, palmtop computer, bidirectional pager or a cellular telephone). emp The recipient intercepts a message to a plurality of user terminals equipment is sent. The Nachrichtendekodierer deco diert the message and identifies a Sitzungssteuerbe fail, which includes an identification number of the User terminal is important. Each user Your Rich tion <b>14</b> may also include a session manager within the DTE to grasp. The session manager performs session control action in response to a session control command (described below ben) by.

In operation, sends a user terminal <b>14</b> After a reporting to a host computer <b>12</b>, The message sent by the User terminal <b>14</b> is sent, by the Benut zerendeinrichtung <b>14</b> to base station <b>32</b> transfer. The base station <b>32</b> provides the user of the terminal <b>14</b> message sent to the ENG <b>20</b>, At this time, a Session identifier and a host identifier or other suitable display that identifies which Benut zerendeinrichtung with which the host computer in communi cation is, in the data base <b>28</b> recorded. Continue back is defined by the user terminal <b>14</b> sent Message temporarily in the buffer <b>22</b> stored. Thereafter the message to the host computer <b>12</b> passed.

When the host computer <b>12</b> failed or is slow to the time at which a message from the user Your Rich tion <b>14</b> to the host computer <b>12</b> Sent there remains the from the user terminal <b>14</b> Message sent in Puf fer <b>22</b>, Thus, all subsequent messages from the user terminal <b>14</b> be sent in the buffer <b>22</b> collect. When the buffer<b>22</b> is full, the error detector <b>24</b> triggered, indicating that at a problem of Communication with the host computer <b>12</b> consists. in response to to the error detector <b>24</b> generates the command generator <b>26</b> egg NEN session abort command and sends the Sitzungsabbruchbe failure by the RNG <b>20</b> to the group of Benutzerendeinrichtun gen. When the session abort command the user Your Rich achieved tions, so listen to the user terminal equipment on, more messages to the host computer <b>12</b> Send to until a Sitzungsanschaltebefehl by Benutzerendeinrichtun gene is received, which indicates that the host computer <b>12</b> again working or that now in the buffer <b>22</b> space available is.

An alternative mode of <b>Fig.</b> 2 occurs when the host computer <b>12</b> a message to a user terminal <b>14</b> sends. The host computer<b>12</b> sends the message to the data communication network <b>10</b>, Within the data communication network <b>10</b> the message by the RNG <b>20</b> receive. At this time, the session <b>40</b>, of the Host identifier <b>42</b> or other suitable host user Communication identifier in the data base <b>28</b> be signed net. The from the host computer<b>12</b> sent message is before temporarily in the buffer <b>22</b> buffered, but the USAGE tion of the buffer <b>22</b> is less important if the message from the host computer <b>12</b> to the user terminal <b>14</b> Gesen det is. The from the host computer<b>12</b> sent message is then the RNG <b>20</b> to base station <b>32</b> come from where they then the user terminal <b>14</b> Gets transferred.

There are different ways to identify the group of user terminals in communication with a spe essential host computer at any one time conceivable. at for example can the host computer <b>12</b> a unique identi fizierer (for example, an Internet protocol address) to are reported. The host identifier is determined by the Group of user terminals identified, and the Group of user terminals determined independently whether they identified with by the host identifier Host computer communicates. Each user terminal equipment via assumes when it is affected, in response, the Sit tion control.

Alternatively, a data communication system <b>5</b> bereitge provides, in the data base <b>28</b> an identification number comprises identifying the user terminals, which by a host computer, which fails, or a buffer <b>22</b> in the CLOSELY <b>20</b>Which reaches a predefined threshold, BE affected are. In response to the identification of the BE affected user terminals transmits the Befehlsgenera gate <b>26</b> a session control command to the at least two Benut zerendeinrichtungen, the identification number of the be affected user terminals comprises. Each user terminal device has devices for receiving the session control command for comparing the identification number, contained in the session control command readied with a voted identification number to the user Your direction is stored, and for receiving a Sit tion tax action if there is a match.

In the preferred embodiment, however, a HUM-Ta belle <b>39</b> in the database <b>28</b> stored. The HUM table represents the routing table, mapping the between the session identifier <b>40</b> for a user terminal facility <b>14</b> and the host identifier <b>42</b> defined. So with, the HUM table <b>39</b> the user terminals <b>14</b> represents that share the same routing table.

<b>Fig.</b> 3 is an example of a table HUM <b>39</b>That in the Da tenbasis the RNG <b>20</b> of the <b>Fig.</b> 2 is stored. A HUM-Ta belle <b>39</b> is in an operators interface system ever the user terminal or group of users you have directions <b>14</b> assigned. If a buffer<b>22</b> the RNG <b>20</b> a predetermined threshold value is reached, or a host computer <b>12</b> fails, so are the RNG <b>20</b> a session control command (Sit tion demolition) to the RNC <b>30</b> out. The session termination command includes any and Hum- session identifier <b>40</b> Combination, a relationship to the problematic host identifier <b>42</b> Has.

In the preferred embodiment, the data base of the Session state for each session identifier <b>40</b> For each HUM table <b>39</b> within the user terminal <b>14</b> even stored. Alternatively, holding a RNC<b>30</b> (example , a control of the RNC <b>6000</b> Serie MOTOROLA Inc.) a database session state for each session Siden tifizierer <b>40</b> for each HUM table <b>39</b> upright. The RNC<b>30</b> begins to subsequent messages received from the user terminal facilities <b>14</b>That are identified by this meeting, be transmitted. At this time, the RNC<b>30</b> a Feh lerantwort to the user terminal <b>14</b> submit.

<b>Fig.</b> 4 is an illustration of the format of an SDU for Sit use management data <b>50</b>, The SDU<b>50</b> comprises a first part <b>52</b> and a second part <b>54</b>, The first part<b>52</b> includes a Type <b>56</b> and a recording session counter <b>57</b>, The second part <b>54</b> comprising the HUM <b>58</b>, A Sitzungsidentifiziererlänge <b>60</b>, A session <b>61</b>And a Sitzungssteu heritage fail <b>62</b>, The second part<b>54</b> can repeated many who the.

The session management data <b>50</b> contain one or more Session recordings, each of which HUM <b>58</b> and <b>59</b>. a session <b>61</b> and a session management command <b>62</b> includes. The session identifier<b>61</b> includes the initial bytes of the data head of the protocol data unit (PDU).

The contents of each lower part of the session management data <b>50</b> are as follows: the type <b>56</b> (8 bits) shows the Type the session management data <b>50</b> to (00 = host computer-to- Users Your directional session control; 01 = user terminal device-to-host computer session control); Sit tion record counters <b>57</b> (8 bits) is the number of Sit use management records, consisting HUM, Sitzungsidentifi Decorators and command exist; the HUM<b>58</b> and <b>59</b> (16 bits) STEL len a double octet field including user Your the directions <b>14</b> defined at which the recording part; the Sitzungsidentifiziererlänge <b>60</b> (8 bits), the number of Octets in the session identifier (0 to 63); the Sitzungsi dentifizierer <b>61</b> (0 to 63 octets) is the variable length field that the session identifier for this Sitzungsauf drawing specified; and the session control command<b>62</b> (va riable length) can take several forms, which he at example a Sitzungsanschaltebefehl, a Sitzungsabschal tebefehl or be a "temporary" Sitzungsabschaltebefehl can.

Preferably a Sitzungsanschaltebefehl and a sit zungsabschaltebefehl a lower limit and a upper interval limit, which define an interval during. the group of user terminals by chance a Time selects to receive data communications again. A random timer <b>8th</b> is the session manager using the alu zerendeinrichtung maintained, to cause the Session control for a random period of time worked. For example, when an error in communication with was identified the first host computer, a session control command (session termination) to the Benutzerendeinrichtun gen output. If the error is corrected, is a two ter session control command (Sitzungsanschalten) to the Benut zerendeinrichtungen outputted, indicating that the error resolved in communication with the first host computer has been. Thereafter, the user terminals use the data communication with the first host computer in a zufälli gen time again. The advantage of defining an Inter valls, during which the group of user terminals randomly selecting a time to the data communications such as the record, is to avoid a situation in a large number of user terminals equal time begins again, messages to the host computer to sen the.

A single SDU, a number of unique and HUM Sit zungsidentifiziererkombinationen identify. furthermore can a single SDU to many users terminals ge be sent to a session control command <b>62</b> to each of the to provide user terminals.

<b>Fig.</b> 5 is an illustration of a protocol stack of the Sy stems of <b>Fig.</b> 2, specifically for the representation of the new Session Manager serves. <b>Fig.</b> 5 went into three sections shares, each section a corresponding protocol stack has. The first paragraph<b>70</b> is a network node. The network node includes higher layers <b>71</b>, A Sit tion manager <b>72</b>, Intervening layers <b>73</b>, A radio connectionless data link layer <b>74</b> (For example, RD-LAP Link layer) and a physical layer <b>75</b> (example as RD-LAP physical layer). The second section<b>76</b> is a radio packet modem. The radio packet modem contains a Funkver bond data link layer <b>77</b> (For example, RD-LAP Compound layer), a physical layer <b>78</b> (example as RD-LAP physical layer), a data link layer <b>79</b> (Eg NCL) and an RS-232 interface <b>80</b>, Of the third section <b>81</b> the DTE. The DTE contains higher layers <b>82</b>, A session manager <b>83</b>, Intervening layers <b>84</b>, A data link layer <b>85</b> (for example NCL) and an RS232 interface <b>86</b>,

<b>Fig.</b> 6 is a diagram of the signaling between ver various elements of the system of <b>Fig.</b> 2 according to a be preferred embodiment of the invention. The following speci fications are taken either when the host computer <b>12</b> fails or if the buffer <b>22</b> full is: HUM = 01; Sit zungsidentifizierer = R2; Timer = 5 (minutes). After that sends the RNG <b>20</b> the session abort command to the RNC <b>30</b> using the aforementioned specifications. The RNC <b>30</b> in turn initiates the transmission of Sitzungsab break instruction by RNG <b>20</b> is received at the base station <b>32</b>, The base station<b>32</b> transmits the Sitzungsab break command on the RD-LAP to the RPM <b>16</b>, The RPM<b>16</b> about then transmits the session abort command to the session manager <b>83</b>, The session manager<b>83</b> either in RPM <b>16</b> or the DTE <b>18</b> be implemented.

<b>Fig.</b> 7 is a detailed flowchart of the implementation the user terminal-to-host computer session control according to the preferred embodiment of the invention. Under in reference to <b>Fig.</b> 7 occur three subprograms <b>110</b>. <b>120</b> and <b>130</b> simultaneously in the main program <b>100</b> on. In the first subprograms program determines the step <b>111</b>Whether a registration trial takes place. If not, is a step<b>114</b> the first Un terprogramm <b>110</b> returns to step <b>111</b>, And waits for to receive a new message to the first subprogram <b>110</b> to repeat. If so, find a Registrierverfah ren in step <b>112</b> instead of. step<b>113</b> initiated the RNG <b>20</b>. add the HUM for Service Authorization message, and sends the Service Authorization message to the user terminal equipment. The session manager of authorized Benut zerendeinrichtung stores its HUM. After completion leads step <b>114</b> the first sub-program <b>110</b> returns to step <b>111</b> and is waiting to receive a new message to the first subprogram <b>110</b> to repeat.

In the second subroutine <b>120</b> determines the step <b>121</b>, if a Host computer fails, or if a buffer in the RNG <b>20</b> is full. The buffer<b>22</b> is full if either the host computer <b>12</b> has failed and subsequent messages from the user terminals to the host computer <b>12</b> sent are, or when the host computer <b>12</b> when receiving or Sending messages is slow. Consequently searched when either the host computer <b>12</b> fails or the buffer <b>22</b> is full, the RNG <b>20</b> the data base to the HUM and the Sit to identify zung Ids, the host with the compound or the Knapp Are the tools in step <b>122</b> connected are. If the HUM and the session IDs are identified, so are the RNG <b>20</b> an SDU (session abort command) to all affected session manager in step <b>123</b> out. The session abort command transfers the HUM and the session ID in a Group of user terminals <b>14</b>That entwe adversely of the failed host computer <b>12</b> or the full buffer <b>22</b> to be influenced. Upon receipt of the Sitzungsabbruchsbe command has heard the user terminals <b>14</b> so on, After sent to the host computer <b>12</b> send, or they verlang seed sending of these messages a (that is, to output session recording command).

The function of the third subroutine <b>130</b> depends on the resultant nis of the second subroutine <b>120</b> from. When a host computer<b>12</b> failed or a buffer <b>22</b> is full, so determined step <b>131</b>When the host computer <b>12</b> be working again begins, or when space in the buffer <b>22</b> is available. If kei nes happens thereof, thus leading step <b>135</b> subroutine continuously to step <b>131</b> back until a confirmation answer in step <b>131</b> Will be received.

When the host computer <b>12</b> again working or if the buffer <b>22</b> Space is available, so searched the RNG <b>20</b> the Datenba sis to identify the HUM and the session ids with the host connection or the Knapp Are the aids in step <b>132</b> are connected. The RNG<b>20</b> then a new SDU (Sitzungsanschaltebefehl) to all concerned Sit tion manager in step <b>133</b> out. The Sitzungsanschaltebefehl are the HUM and the session IDs to the group of Benut zerendeinrichtungen from that adversely either from failure Host computer <b>12</b> or the full Become the buffer <b>22</b> be affected are. If the Sitzungsanschaltebefehl from Benut zerendeinrichtungen <b>14</b> is received, so they can continue Messages to the specific host computer <b>12</b> according to the above Send mentioned random time period.

<b>Fig.</b> 8 is a diagram of the signaling between ver various elements of the system of <b>Fig.</b> 2 according to an al alternatives embodiment of the invention. This alternative Embodiment is particularly useful when one or several DTEs <b>18</b> no session termination in response to egg can perform NEN session abort command. The following Specifications are either taken if the host Com computer <b>12</b> fails or if the buffer <b>22</b> full is: HUM = 01; Session identifier = R2, timer = 5 (minutes). After that are the RNG <b>20</b> a session termination command to the RNC <b>30</b> out. At any time thereafter sends the RPM<b>16</b>/the DTE <b>18</b> a message from the user terminal to the Host computer to HUM 01 and the session identifier R2 belongs. As a result of the advance from the RNG<b>20</b> issued Session termination command responds the RNC <b>30</b> According to the reporting, by the user terminal to the host computer was sent by outputting an error message ( "NAK SDU not available ") to the user terminals.

<b>Fig.</b> 9 is a detailed flowchart of the implementation the user terminal-to-host computer session control according to the alternative embodiment of the invention. Refers one to be <b>Fig.</b> 9, so shall the subroutine <b>170</b> within the main RNC program <b>145</b> on. In this embodiment, maintains the RNC <b>30</b> a (not shown) Session Manager for each user terminal. The RNC<b>30</b> draws the Sit zungsanschalte- and Sitzungsabschalte state for each Benut zerendeinrichtung on.

The outputting a session termination command by the RNG <b>20</b> at the RNC <b>30</b> influenced the session management status, with this user terminal <b>14</b> connected is. The reception a message from the user terminal <b>14</b> triggers the operation of the subroutine <b>170</b> the main RNC program <b>145</b>, If the RPM<b>16</b>/ DTE <b>18</b> subsequent messages from the user terminals outputs that the affected HUM and the session identifier includes before the RNG <b>20</b> egg outputs NEN Sitzungsanschaltebefehl, captures the RNC <b>30</b> the Message in step <b>172</b> on. In step<b>173</b> protects the RNC <b>30</b> the data communication network <b>10</b> by stopping by following sent by the user terminal after report warning that this RNG <b>20</b> achieved and an error message ( "SDU NAK not available") to the RTM <b>16</b>/ DTE <b>18</b> outputs. The step<b>174</b> executes the subroutine <b>170</b> back to step <b>171</b>To it so the RNC <b>30</b> to allow contin ously error messages to the RPM <b>16</b>/ DTE <b>18</b> for all outputting subsequent messages received from the user terminal equipment to be sent, the HUM to the affected and Session identifier belong to the RNG <b>20</b> a new SDU (Sitzungsanschaltebefehl) to the RNC <b>30</b> outputs or the Session break time expires. Finally, the Host computer <b>12</b> work again, or it will place in Puf fer made available, and the operation is as before lau fen.

<b>Fig.</b> 10 is a flowchart of a session control according to another aspect of the invention. The initial query is used to determine whether the RNG <b>20</b> a message from a Host computer <b>12</b> for a user terminal <b>14</b> receive Has. If so, asks step<b>182</b>Whether the user Your direction <b>14</b> there is no meeting, as previously was noted. If so, so determined step<b>183</b>, if the displayed time of sessionless state expired is. If so, then in step<b>184</b> the user terminal equipment <b>14</b> switched to the session state, and the Message will be a normal operation in step <b>185</b> ge sends.

If you were to step <b>182</b> returns, when the Be user your device is not in any session, as before noted, but the time of the state in sessionless step <b>183</b> has not expired, the message in step <b>186</b> either buffered or discarded. If you again to step <b>182</b> referring back, then when the Benut zerendeinrichtung <b>14</b> is not in session down state As previously mentioned, the message then a NOR painting operation in step <b>185</b> Posted.

Referring now back to step <b>181</b>So determined, if the RNG <b>20</b> any message from a host computer <b>12</b> for a user terminal <b>14</b> receives, and the RNG <b>20</b> in step <b>187</b> a message from a user Your Rich tion <b>14</b> for a host computer <b>12</b> receiving step <b>188</b>, if the message is a session termination message. If so is, the user terminal in step <b>189</b> For an indicated time connected in the session state. If this is not so, so determined step <b>190</b>Whether by directing a Sitzungsanschaltenachricht is. If it's like that, then the user terminal <b>14</b> in step <b>191</b> in the Session State connected. If the answer in step<b>190</b> is negative, then the message in step <b>192</b> over a normal operating processes.

While the invention in connection with specific From lead shape has been described, it is apparent that Many changes, modifications, and variations compartment people in the light of the foregoing description clearly who the. Thus, it should be understood that the invention by the foregoing description is not limited, son countries all such changes, modifications and variation in accordance with the spirit and scope of the appended claims to summarizes.