Server time protocol messages methods

METHOD AND EQUIPMENT FOR SERVER TIME PROTOCOL

Technical Field

[001] The present invention relates, in general, to the time synchronization within and through a network of processing units and, in particular, to the messages and time protocol methods of the server that facilitate the servers in a network of time synchronization, for example, for the same primary time reference root.

Background of the Invention

[002] For performance and data integrity reasons, computing systems that access shared data, such as SYSPLEX, offered by International Business Machines Corporation, Armonk, New York, must be able to keep the time of day clock synchronized ( TOD) with an accuracy that is better than the best communication time between systems. Currently, in an example, to meet synchronization requirements, a timer, such as the IBM® 9037 SYSPLEX, is used. This timer requires expensive dedicated timing connections and a separate external box.

[003] Other networks, such as Time Protocol for Networks (NTP), provide time synchronization, but do not meet the precision requirements of high quality systems. NTP requires that each server has access to an external source of time that provides precision to a microsecond level to ensure that all servers synchronize with the same reference time. This is an issue for systems that do not have the ability to connect to external time servers that provide this level of accuracy. In addition, a requirement for GPS receivers or a similar attachment on each

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-2/49 The system can be considered impractical for reasons of maintenance, safety and reliability.

Summary of the Invention

[004] The weaknesses of the state of the art are overcome and additional advantages are provided by providing a method of exchanging messages to facilitate the synchronization of the processing units of a timing network. The method includes: generating a conversion time parameter (XTP) message command in a first processing unit, the XTP message command including a message transmission time stamp field, defined by the first processing unit, and a message receipt time stamp field, deactivated by the first processing unit; setting the message command receipt time stamp field in the XTP message command to the time the XTP message command is received at the second processing unit; and generating an XTP message response in the second processing unit, the XTP message response, including the message transmission time stamp set by the first processing unit and the message command receiving time stamp defined by the second processing unit obtained through the XTP message command.

[005] The products of systems and computer programs corresponding to the methods summarized above are also described and claimed herein.

[006] Additional features and advantages are realized through the techniques of the present invention. Other representations and aspects of the invention are described in detail here and are considered part of the claimed invention.

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-3 / 49Brief Description of Drawings

[007] The subject in reference which is considered as the invention is particularly described and claimed distinctly in the claims at the end of the specification. The foregoing considerations and other objects, features and advantages of the invention are evidenced from the following detailed description considered in conjunction with the accompanying drawings in which:

[008] FIG. 1A illustrates an example of a coordinated mixed time synchronization network to incorporate one or more aspects of the present invention;

[009] FIG. 1B illustrates an example of a STP-only network to incorporate one or more aspects of the present invention;

[010] FIG. 2 illustrates an example of a stratum-1 configuration information block, in accordance with an aspect of the present invention;

[011] FIG. 3 illustrates an example of a new stratum-1 configuration information block, in accordance with an aspect of the present invention;

[012] FIG. 4 is a flow chart of a representation of the command processing of the XTP message, in accordance with an aspect of the present invention;

[013] FIG. 5 depicts a representation of a command format of the XTP message, in accordance with an aspect of the present invention;

[014] FIG. 6 is a flow chart of a response processing representation of the XTP message, in accordance with an aspect of the present invention;

[015] FIG. 7 depicts a representation of an XTP message response format, in accordance with an aspect of the present invention;

[016] FIG. 8 depicts a representation of an XTP message response data format, in accordance with an aspect of the present invention;

[017] FIG. 9 depicts another representation of the XTP message response data format, in accordance with an aspect of the present invention;

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[018] FIG. 10 depicts yet another representation of the XTP message response data format, in accordance with an aspect of the present invention;

[019] FIGS. 11A and 11B depict a command transmission process of the XTP message, in accordance with an aspect of the present invention;

[020] FIG. 12 is a flowchart of a processing representation associated with an XTP response message transmission procedure, in accordance with an aspect of the present invention;

[021] FIG. 13 depicts a command format representation of the STP control message (STC), in accordance with an aspect of the present invention;

[022] FIG. 14 depicts a representation of the response format of the STC message, in accordance with an aspect of the present invention;

[023] FIG. 15 depicts a representation of a new stratum-1 configuration information block, in accordance with an aspect of the present invention;

[024] FIG. 16A illustrates an example of a CTN reading parameter response in an operation dependent area format, in accordance with an aspect of the present invention;

[025] FIG. 16B illustrates an example of a "general reading CTN parameter parameters" data area format, in accordance with an aspect of the present invention;

[026] FIG. 17A illustrates a representation of an STP path command established in an operation-dependent area format, in accordance with an aspect of the present invention;

[027] FIG. 17B illustrates an establishment representation of an arbitrary server control take-over response in a "dependent operation" area format, in accordance with an aspect of the present invention;

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[028] FIG. 18 illustrates a representation of a processing environment to incorporate one or more aspects of the present invention;

[029] FIG. 19 illustrates more details of the memory of FIG. 18, in accordance with an aspect of the present invention; and

[030] FIG. 20 illustrates an example of a computer program product to incorporate one or more aspects of the present invention.

Best Mode for Implementing the Invention

[031] In accordance with an aspect of the present invention, messages and processing methods of the server time protocol (STP), employing these, are provided to, for example, transfer timing information between two servers in a timing network to facilitate your synchronization. The exchange time parameters (XTP) messages and the STP control messages (STC) are described.

[032] Although several networks can be configured to include a tier-1 server, one such network is a Coordinated Timing Network. (CTN). In a Coordinated Timing Network, multiple different computing systems maintain time synchronization to form the Coordinated Timing Network. Systems in the Coordinated Timing Network employ a message-based protocol, referred to as a Server Time Protocol (STP), to pass time recording information between systems allowing high-speed data connections. This allows time-of-day (TOD) clocks on each system to be synchronized with the precision required in today's high-tech computing systems. Since the protocol makes use of the technology within a computer system, the synchronization accuracy increases as the technology improves. A computer system that provides an STP mechanism is referred to here as a time server or server.

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-6 / 49 [033] A server defined in a CTN as a primary time server provides primary reference time for the CTN. The server in a CTN, which determines the CST (an estimate of the time of day clock (TOD) for the CTN), based on information from another server in the CTN, is called the secondary time server. The primary time server can obtain its time from an external time source, which provides the means to synchronize the time clocks in a CTN to a defined time pattern.

[034] Servers in a CTN, which are in synchronized condition, receive a value, referred to as a stratum level, which specifies the number of servers between it and a primary time server. A primary time server operates at a stratum level of 1; secondary time servers operate at a stratum level of 2 or higher, which increases as the number of servers in the timing path to stratum-1 increases. In general, the quality of time recording information decreases as stratum level increases. The server that is not synchronized is assigned a stratum level of 0.

[035] The STP installation provides the necessary procedures to transmit, receive and process messages from the STP. STP messages are transmitted over one or more physical data connections between servers. The data connection that has been established between two servers is called an STP path. The installation of STP provides the facilities to establish and maintain the paths of the STP.

[036] STP messages include a message command and a message response. Two types of STP messages are supported. The exchange time parameter message (XTP) and the STP control message (STC). The XTP message is used for the exchange of time stamp information used to determine CST for CTN. STP control messages are used to define and modify various CTN parameters required by servers in CTN.

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-7 / 49 [037] A CTN can operate, for example, as one of two types of configurations: either as a mixed CTN configuration or as a STP-only CTN configuration. In a mixed CTN configuration, the servers are configured to be part of both an STP network and an External Time Reference (ETR) network. In a mixed CTN configuration, the servers in the CTN are configured with the same non-null ETR network ID and a timer (for example, 9037 SYSPLEX timer) provides the primary time reference for the CTN. At least one server in the CTN must pass to timing signals provided by the SYSPLEX timer before synchronization can take place within the CTN. Servers that do not switch to the SYSPLEX timer are secondary time servers and achieve synchronization by exchanging STP signals, as described below.

[038] As an example, each server that passes to the SYSPLEX timer time signals receives the time protocol parameters and propagates the information to secondary time servers in the CTN, using, for example, a parameter update procedure from CTN.

[039] An example of this process is described in US Patent Application No. 11 / 468,352, entitled “Coordinated Time Network Configuration Parameter Update Procedure”, Carlson et al., Filed on August 30, 2006.

[040] An example of a mixed CTN configuration 100 is described with reference to FIG. 1.A. Configuration of the mixed CTN 100 includes, for example, a Server A (102) coupled to a local area network (104), a Server B (106) coupled to the local area network (104) and a Server C (108) coupled to a local area network (110). Each server is, for example, a central processing complex based on z / Architecture® offered by International Business Machines Corporation. z / Architecture® is a registered trademark of International Business Machines Corporation, Armonk, New York, USA. A representation of z / Architecture ® is described in “Operating Principles z / Architecture” IBM Publication No. SA22-7832-04, September 2005.

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-8 / 49 [041] Each local area network is coupled to a console 120 used to provide time synchronization within the network. In addition, the local area network 104 and the local area network 110 are coupled to each other via a wide area network 112.

[042] Servers A and B are coupled to an external time reference network 114 and Servers B and C are configured to integrate a network of STP 116. Server B is at tier-1 level and Server C is one stratum-2 level. Connections from STP 118 are used to couple the STP feature of Server B with the STP feature of Server C.

[043] In an STN-only CTN, the servers in the CTN are configured to be part of an STP network and none are configured to be part of an ETR network. An example of a STP network only 150 is described with reference to FIG. 1B. In this example, Server A (152) and Server B (154) are coupled to a LAN (156) and Server C (158) is attached to a LAN (160). Each of the servers includes an STP 162 facility, and each facility is coupled to one another through one or more STP 164 connections.

[044] In addition, LAN 156 is coupled to a console 170 and LAN 160 is coupled to a console 172. Console 170 is further coupled to an external time source (ETS) 174, such as a dial out for a phone time service (for example, ACTS: NIST Automated Computer Time Service). In this network, there is no ETR network. Server B has a stratum level of 1, and Servers A and C have a stratum level of 2.

[045] The server that is to act as a layer-1 server active on the network, as a STP network only, is specified as part of a layer-1 configuration defined for the network. The stratum-1 configuration is maintained on each server in the network and provides information related to the network configuration, including, for example, the type of configuration defined for the network. The network can be configured as one of several types, including, for example:

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a) Null configuration - in a null configuration, a stratum-1 server is not identified. The server remains unsynchronized until it connects to a server that has a non-null layer-1 configuration. The stratum-1 configuration on a server that is at stratum level 0 is equal to the null configuration when, for example, it is not connected to any other server and the only CEC CTN indicator in a stratum configuration information block 1, described below, is zero.

b) Definition of Single Server - in a single server definition, the layer-1 configuration defines a single primary layer-1 server that acts as the layer-1 active server for CTN. The loss of the primary stratum-1 server results in the loss of synchronized time on the CTN until a new stratum-1 configuration is specified on the console.

A single tier-1 server configuration may also include an indication that the specified tier-1 server is the only server (for example, electronic computing complex (CEC) or (CPC) at CTN and that no other server or additional servers will be part of the CTN, in which case the CTN is referred to as the CEC's only CTN. When a layer-1 configuration indicates that it is a single CEC CTN, the configuration is a layer-1 configuration valid for the initialized state of the server after a restart of the connection. When a stratum-1 single server configuration does not specify that it is a single CEC CTN, the configuration is not a valid stratum-1 configuration for the initialized state of the server after restarting the connection and the stratum-1 configuration is defined as null setting.

c) Dual Server Configuration - In a dual server configuration, the configuration includes a primary tier-1 server and an alternate tier-1 server. The use of a dual server configuration provides a mechanism for an alternate server to assume the role of tier-1 active server for CTN. The backup server

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-10 / 49estrato-1, when configured with the same connectivity to other servers in CTN as the primary stratum o-1 server , can assume as active stratum-1 without interrupting CTN's synchronization capacity. The tier-1 server (primary or alternate) that is acting as the tier-1 active server for a CTN is indicated in the tier-1 configuration information block maintained on each server in the CTN, as described below. The tier-1 server that is not the tier-1 active server is defined as the tier-1 inactive server.

[046] The tier-1 inactive server in a dual-server configuration assumes the role of the tier-1 active server when it detects a tier-1 active failure. A stratum-1 active failure is detected in a dual server configuration when one of the following occurs:

• An assisted console recovery procedure is performed and indicates that a stratum-1 active failure has occurred, or • A stratum-1 system check signal is recognized.

[047] The tier-1 inactive server in a dual-server configuration performs assisted console recovery when the tier-1 inactive server loses its connection with the tier-1 active server.

d) Triad configuration - in a triad configuration, the stratum-1 configuration includes a primary stratum-1 server, an alternate stratum-1 server, and an arbitrary server. Defining a triad configuration provides a mechanism for an alternate server to assume the role of the tier-1 active server for CTN, as defined for a dual server configuration. Additionally, the definition of arbitrary server, when configured with connectivity for both the tier-1 primary server and the

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-11 / 49 stratum-1 alternative, provides a mechanism for inactive and arbitrary stratum1 servers to communicate with each other in order to determine that a stratum-1 active server failure has occurred and that the stratum-1 inactive should take over as the server stratum-1 asset.

[048] The inactive stratum-1 server in a triad configuration assumes the role of active stratum-1 when it recognizes a failure in the active stratum-1. The inactive tier-1 server recognizes an active tier-1 failure when any of the following occurs:

• A triad recovery procedure is performed and indicates that a failure in the active stratum-1 has occurred.

• An assisted console recovery procedure is performed and indicates that a failure has occurred in the active layer-1.

[049] The stratum-1 inactive server performs the triad recovery procedure when the following conditions occur:

• The inactive tier-1 server loses connection with the active tier-1 server and is connected to the arbitrary.

• The inactive layer-1 server recognizes an active layer-1 communication interval and is linked to the arbitrary.

[050] The tier-1 inactive server performs assisted console recovery when the tier-1 inactive server loses its connection with the tier-1 active server and is not connected to the arbitrary.

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-12 / 49 [051] The inactive tier-1 server performs the procedure of taking control of the active tier-1 to assume the role of the active tier-1 server for CTN.

[052] The tier-1 active server in a triad configuration abandons the tier-1 active server when it detects that it has lost connection with both the inactive tier-1 server and the arbitrary server. The stratum-1 active server performs an active stratum-1 surrender procedure to give up the stratum-1 active server role for CTN.

[053] In one example, layer-1 configuration information is kept in a control block, called layer-1 configuration information block (SCIB), which is stored on or accessible to each server on the network. The SCIB is used to identify the stratum-1 configuration for a network.

[054] A representation of a layer of configuration information of layer 200 is described with reference to FIG. 2. The tier-1 200 configuration information block includes, for example, the following fields:

a) Primary Stratum-1 Node Descriptor 202: this field is valid when a single server, double server or triad definition has been specified in the configuration type field of the configuration information block, described below and when valid, includes the node descriptor of primary stratum-1 node descriptor.

b) Alternative Stratum-1 Node Descriptor 204: This field is valid when a double or triad server definition has been specified in the configuration type field and when valid, includes the node descriptor of the server node descriptor stratum-1 alternative.

c) Arbitrary Node Descriptor 206: This field is valid when a triad definition has been specified in the configuration type field and includes the node descriptor of the arbitrary server node descriptor.

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d) Stratum-1 configuration time stamp 208: This field includes a time stamp indicating the time when the stratum-1 configuration information in this block became current on the server.

e) Configuration Type (CType) 210: This field specifies the type of configuration of layer-1, as defined below:

• Null definition - None of the node descriptors are valid.

• Single server definition - Only the stratum-1 primary node descriptor is valid.

• Dual Server Definition: The primary stratum-1 and alternative stratum-1 node descriptors are valid.

• Triad definition: The primary stratum-1, alternative stratum-1 and arbitrary node descriptors are valid.

f) Stratum-1 Active (A) 212: This field is valid when a double server or triad definition has been specified and indicates whether the primary stratum-1 server or the alternate stratum-1 server is the active stratum server -1.

g) Single CEC CTN (X) 214: This field is valid when the configuration type specifies a single server definition and when, for example, one indicates that the CTN is the only CEC CTN. When the field is, for example, zero, the CTN is not the only CTN of the CEC.

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h) Recovery Configuration (R) 216: This field indicates whether the layer-1 configuration described by this block is the result of a layer-1 recovery action or a console command.

i) Maximum Variation of Stratum-1 Short Term Distortion Rate 218: This field includes a value that specifies the maximum possible change in the distortion rate of the physical oscillator on the stratum-1 server that can occur during any specified period (for example, example, 60 seconds). This field is used to form a value that is in the same format as the base steering rate. On machines that are not capable of performing dynamic oscillator switching, the value is equal to the maximum frequency fluctuation of the stratum-1 oscillator that can occur during a specified period (for example, 60 seconds). On machines that are capable of performing dynamic oscillator switching, the value is defined as the maximum distorted tolerance range specified for the oscillator. For example, on a machine that supports dynamic oscillator, alternating with oscillator distortion tolerance specified at +/- 2 ppm the nominal frequency, the value is set to the equivalent of 4 ppm. A dynamic oscillator switchover occurs when the physical oscillator used to drive the system's TOD clock is switched from one oscillator to another.

[055] In addition to the control block above, another control block, called the new layer-1 configuration information block (NSCIB), can be used to specify a new layer-1 configuration for CTN. In addition, it can be used to specify an update to the CTN ID that must occur simultaneously with the stratum-1 configuration change.

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-15 / 49 [056] An example, the NSCIB on a server is significant when the server is configured to be part of a STP CTN configuration only or if the STP migration part of the NSCIB is equal to one.

[057] A representation of a new block of configuration information of layer 1 300 is described with reference to FIG. 3. The new layer of configuration information for layer-1 300 includes, for example, the following fields:

a) Stratum Node Primary Descriptor-1 302: This field is valid when a single server, dual server or triad definition has been specified in the configuration type field and includes the stratum-1 primary node descriptor.

b) Alternative Stratum Node Descriptor-1 304: This field is valid when a double or triad definition server has been specified in the configuration type field and includes the node descriptor of the alternative stratum-1 node descriptor.

c) Arbitrary Node Descriptor 306: This field is valid when a triad definition has been specified in the configuration type field and includes the node descriptor of the new arbitrary node descriptor.

d) Stratum-1 Configuration Update Time 308: When the server is configured to be part of a STP CTN only, this field includes a time stamp indicating when the values ​​in this block should become current for the CTN . When the server is not configured to be part of an STP CTN only, the field has no meaning.

e) Type of configuration (CType) 310: This field specifies the type of layer-1 configuration, as defined below:

• Null definition - None of the node descriptors are valid.

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-16 / 49- • Single server definition - Only the layer-1 primary node descriptor is valid.

• Dual Server Definition: The primary stratum-1 and alternative stratum-1 node descriptors are valid.

• Triad definition: The primary stratum-1, alternative stratum-1 and arbitrary node descriptors are valid.

f) Stratum-1 Active (A) 312: This field is valid when a double server or triad definition has been specified and indicates whether the primary stratum-1 server or the alternate stratum-1 server is an active stratum server -1.

g) Changing the CTN ID (C) 314: When the server is configured to be part of the STP CTN only, this field indicates whether a change to the CTN ID is being requested and the CTN identification is valid. The change occurs in the layer-1 configuration update time.

CTN identification is a value that is used to identify a CTN. The CTN ID includes, for example, an STP network ID and an ETR network number. The STP network ID identifies the STP network, if any, that is configured for the server. The ETR network number identifies the ETR network number, if any, that is configured for this server.

h) STP (S) 316 Migration Configuration: This field is significant when, for example, the server is not configured as an STP CTN only. The field indicates whether a STP migration layer-1 configuration has been defined for the server only. When the field is,

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-17 / 49for example, one, the NSCIB includes the stratum-1 configuration which must become current when the CTN ID on the server is changed to an STP configuration only. When the field is zero, an STP migration layer-1 configuration is just not defined for the server.

i) Single CTN of the CEC (X) 318: This field is valid when the configuration type specifies a single server definition and when one, for example, indicates the CTN is the only CTN of the CEC. When the field is, for example, zero, the CTN is not the only CTN of the CEC.

j) Recovery configuration (R) 320: This field indicates whether the layer-1 configuration described by this block is the result of a layer-1 recovery action or a console command.

k) Maximum Variation of Stratum-1 Short Term Distortion Rate

322: This field includes a value that specifies the maximum possible change in the distortion rate of the physical oscillator on the new stratum-1 server that can occur during any specified period (for example, 60 seconds).

l) New CTN ID 320: This field is valid when the CTN ID change indicator specifies the change request for a valid CTN ID and a valid CTN ID. This field specifies the new CTN ID.

[058] If the new stratum-1 configuration information block is not to be used to specify an update to the CTN ID, then the block cannot include the CTN ID change piece or the new CTN ID, for example. Additional details on coordinated time networks and the definition of a stratum-1 configuration for a time network are described in

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-18 / 49following US patent applications (USA): S. Carlson et al., “Facilitating the Synchronization of Servers in a Coordinated Time Network”, Application No. 60 / 887,584; and S. Carlson, “Defining a Stratum-1 Configuration in a Coordinated Time Network”, Order No. 60 / 887,652.

[059] As noted initially, in one aspect, here are the command of the exchange time parameters (XTP) and response messages, as well as server time protocol control (STC) messages for a protocol installation. server time, as described above. Again, server time protocol (STP) messages are transmitted along STP paths between two servers in the form of a message command and a message response. A message command is sent from a server to an attached server; and a response from the STP message is sent from a server to an attached server in response to a command from the message received from the attached server. The message response is sent to the server attached to the connection through which it sent the message command. As used here, a server sending a message command is called the message originator, while a server receiving a message command is referred to as the message recipient. A message command contains a message command code that indicates the type of message being transmitted. For example, the STP message command codes can support:

• Exchange Time (XTP) parameter messages • STP Control Messages (STC)

[060] The message response contains a response code that describes the result of the attempt to execute the message command. Generic responses are defined below. Not all responses are applicable to all commands in the message. Additional command-dependent responses can be defined for individual commands. When several conditions of

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-19 / 49response can be detected simultaneously, lower number response code can be reported.

[061] Command Codes:

• Success: The message command was successful.

• STP not enabled: The STP feature is installed, but not enabled on the attached server.

• Busy: The message command cannot be executed at this time due to busy conditions or resource constraints.

• Invalid Operation Parameters: The message command contains invalid parameters.

• Configuration error: The message command contains an incompatible CTN ID.

• Path not established: The path is not established on the attached server.

• CF response: Indicates that the STP feature is not supported on the attached server.

[062] The exchange time parameter message (XTP) is used to exchange the time stamps, time registration information and CTN parameter information between two directly attached servers. The information in the message response is used by the message originator to calculate the complete delay, compensation and dispersion values ​​that are used by STP clock selection and filtering algorithms to select a clock source. It is also used to set CTN time recording parameters and ensure synchronization of attached servers.

[063] The STP facility on the server maintains a history of the time stamp and time stamp information received in the XTP message responses in an XTP tracking matrix. The number of samples held in the matrix may vary. XTP transmission procedures are used to transmit XTP message commands, and

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-20 / 49XTP receipt are used to receive XTP messages, as described below.

XTP command message

[064] As shown, by the example of FIG. 4, the STP facility on the server that sends an XTP message command defines all message command fields, except for the message-command-receive time stamp 410 field. The XTP message command fields are defined by the message's origin server at the time the message is sent. A command format of the XTP message is shown in FIG. 5. In this format, message header 510 contains information that is dependent on the type of data connection used to implement the STP connection. Command code 520 contains an indication of the command of the specific XTP message. XTP Format 530 contains a value that specifies the format of the area-dependent-format in the message command. This value can be set to zero for message commands. The CTN ID 540 is defined as the CTN ID of the server that sends the message command, that is, the origin server. The command transmission time stamp of message 550 is defined as the day-time clock (TOD) on the origin server on the date the message is transmitted over the STP path by the server. The command receipt time stamp for message 560 is set by the receiving server, as explained below. Data dependent on the XTP 570 format is set to zero for an XTP message command.

[065] Continuing with FIG. 4, the XTP message command is forwarded to an attached server, that is, the message 420 recipient server. The command message recipient server defines the “message command receipt time stamp” field in the message command. XTP message at the time the message is received at that server 430. The command receiving time stamp field

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-21 / 49message is set from the time of day (TOD) clock on the receiving server when the message command is received. Again, at the time the XTP message command was transmitted on the origin server, the message command receipt time stamp field was undefined.

[066] The message recipient checks for STP path errors and, if detected, invokes error recovery procedures. Otherwise, the recipient server stores the message command's “inbound message timestamp” data in the timestamp data for the recipient server, and executes an XTP message response to generate and transmit a message. response 440 (FIG. 4).

XTP Reply Message

[067] FIG. 6 describes a representation of the protocol for generating and handling an XTP message response. The STP facility that receives the XTP message command, that is, the server that originates the XTP response message, defines all response fields in the message at the time the response message should be sent, except for the marker field. time “receipt of message response” 610.

[068] FIG. 7 describes a representation of an XTP message response format. In this format, the fields are defined as follows:

• Message header 700: Contains information that is dependent on the type of data connection used to implement the STP connection employed.

Response Code 705: It is an integer that describes the results of trying to execute the message. Valid response codes can include:

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1. Success: The message command was successful.

two. STP not enabled: The STP feature is installed, but not enabled on the attached server.

3. Configuration error: The message command contains an incompatible CTN ID.

4. The path not established: The path is not established on the attached server.

5. CF Response: Indicates that the STP feature is not supported on the attached server.

• XTP 710 format: Specifies the format of the format-dependent area in the message response, which, for example, can include valid values ​​of 0, 1 and 2, as explained below.

• CTN 715 Parameter Key: Indicates whether the contents of the format-dependent area have been changed. The field is only valid in STP CTNs only. In a mixed CTN, the field is negligible and ignored. The stratum-1 active server increments the CTN parameter key whenever it changes the format used in replying to the XTP message or when it changes any value in the data sent in the format-dependent data area. A secondary time server sets the CTN 715 parameter key to the value it received in the last response to the XTP message from its current clock source or, if it does not have a clock source, to the same value sent in its last response to the XTP. The initialized value is zero, and the field encapsulates zero.

• 720 layer: It is defined for the layer level of the server that sends the message response.

• Timer Mode 725: It is set to the timer mode code of the server that sends the message response.

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-23 / 49- • Timer Status 730: It is set to the timer status code of the server that sends the message response.

• Local Clock Server (L) 735: Specifies whether the server that sends the message response is configured as a local clock server.

• CTN ID 740: It is set to the CTN ID of the server that sends the message response.

• Current PRT Correction Direction Rate 745: Contains the current PRT correction-direction rate for CTN. In the XTP message responses sent by the tier-1 server, it contains the PRT correction direction rate that was in effect at the time the message was sent. In XTP message responses sent by secondary servers, the field is set to the value received in the most recent XTP message response received from the clock source to the server. The PRT correction direction rate (PCSR) is used to correct an error accumulated between the current TOD clock on the active tier-1 server and the primary reference time. In a mixed CTN, the PCSR is set to zero.

• Message Command Transmission time stamp 750: It is set for the “message command transmission” time stamp.

• Message Command Receipt Time Stamp 755: It is set to the “message command receipt” time stamp.

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-24 / 49- • Transmission time stamp for message response 760: It is set for the TOD clock of the server that sends the message response at the moment the message is transmitted.

• Time stamp for receiving message response 765: Contains the time stamp for the moment when the message response is received by the attached server. The field is set with the TOD clock on the server that receives the message response when the message response is received.

• Message interval 770: It is defined for the message interval-outgoing time field of the attached server keeping the parameters defined in the sending server.

• Base Direction Rate 775: It is set to the base direction rate of the server that sends the message response.

• Root 780 delay: It is defined for the CST round-trip delay on the server for sending the message response.

• Root scatter 785: It is set to spread the CST clock on the server that sends the message response.

• 790 Reference Identifier: It is defined for the CST reference identification on the server sending the message response.

• Reference time stamp 795: It is set to the reference time stamp CST on the server sending the message response. The time stamp format is in the STP time stamp format.

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-25 / 49-

- Data dependent on the XTP 799 format: It is defined based on the format field. Three fields of message response format are described in FIGS. 8, 9 and 10.

[069] FIG. 8 depicts format 0 data for message response (which is used to provide general CTN parameter information) and includes the general format XTP 810, the correction direction block (PCSB) 820, a new CTN ID block (CIB ) 830, a block of information for adjusting the second (LSOIB) 840, and displacement of a total time 850. The format data-1 of the message response of FIG. 9 are used to deliver a new layer of 1-layer configuration information, and, if specified, a new CTN ID, and include a new general XTP 910 format and a new layer of 1-layer configuration information 920. The message response format-2 data of FIG. 10, which includes a general XTP 1010 format and a time control parameter information block (TCPIB) 1020, is used to deliver a time control parameter as a time zone control parameter information block.

[070] Returning to FIG. 6, the XTP message response is forwarded to a message response receiving server 620, which as noted, is the attached server originating from the XTP message command. The attached server defines the message response receipt time stamp field in the XTP message response when the message response is received 630, and invokes a response procedure for the received XTP message 640 (described below). As noted above, XTP transmission procedures are used to transmit an XTP 420 message command (FIG. 4) or an XTP 620 message response (FIG. 6), as explained further below.

[071] The format used for a response from the XTP message by a primary time server depends on whether an update of the CTN parameter is in progress. If an update is in progress, then the primary time server uses the format that contains the parameter to be updated. When a CTN parameter update is not in progress

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-26 / 49 time, the XTP format-0 message response can be used for all responses. The format used for an XTP message response by a secondary time server depends on whether the server has a clock source. When the server has a clock source, it uses the same format as provided for in the last valid response from the clock source. When the server does not have a clock source, it uses the 0 format response.

Command Transmission of the message

[072] The XTP message command transmission procedure is used to transmit the exchange time parameters (XTP) message command to a specific, attached server. The STP path that is used to transmit the message is determined using, for example, a dependent model STP path selection procedure.

[073] The initiative to issue an XTP message command is established when the message interval timer for an attached server ends. The message interval parameter for the attached server specifies the rate at which XTP message commands are sent to the attached server.

[074] The XTP message command transmission procedure establishes the message header, sets the message command code equal to the XTP command code and constructs the rest of the XTP message command. Just before sending the message, the message command transmission time stamp on the message command is set to the current TOD clock and the command is transmitted along the selected STP path. If a non-delivery condition of the STP message is detected, an invalid entry is added to the XTP trace matrix.

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-27 / 49Transmission of message reply

[075] The message reply transmission procedure is used to transmit an XTP message reply following receipt of an XTP message command. The procedure creates the response message header, defines the message response code, and creates the rest of the XTP message response. Just before sending the message, the message response transmission time stamp in the message response is set to a value equal to the current time of day and the response is transmitted in the STP path over which the message command was received. .

XTP Receiving Procedures

[076] XTP receipt procedures are used to receive an XTP message command or an XTP message reply.

Reply Message Received

[077] FIGS. 11A and 11B depict a logical representation implemented for processing the receiving response of the XTP message. The XTP message response response procedure is invoked whenever an XTP message response is received on an STP path.

[078] The procedure initially searches for an STP 1110 path error, and if an error is detected, an error recovery procedure 1120 is invoked. If no STP path error is detected, then the STP message response is added to the XTP tracking matrix and the entry code is set to 1130.

[079] The entry code is set to a first value of 1140 to indicate that the time stamp data is invalid if any of the following conditions are true:

• Any time stamp contains all zeros, or

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-28 / 49- • The delay state is the stopped state.

[080] If the entry code is not set as the first value, then the entry code is set to a second value 1150 to indicate that the time stamp data is valid, but the entry should not be used to determine an clock source usable if any of the following conditions are true:

• The message response timing status indicates that it is not synchronized, • The message response layer of the attached server is equal to the maximum layer parameter, or • The server layer level is different from zero and the response layer of the message is greater than this value.

[081] If the entry code is not defined as the first value or the second value, then the entry code is defined as a third value 1160 (FIG. 11B), indicating that the entry contains valid timestamp data, and the following actions are performed:

• The timestamp reference data associated with the attached server is updated from the information in the message response.

• Clock filtering and selection processes are performed.

• A clock update procedure is performed.

[082] If the server is in a synchronized state, then the data in the “format-dependent data” field the most recent valid response message is checked for updates and, if detected, the data is used to update CTN parameters of the 1170 server.

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-29 / 49Message command received

[083] The “receive XTP message command” procedure is invoked whenever an XTP message command is received on an STP path. FIG. 12 depicts a representation of such a procedure. As illustrated, the procedure includes STP 1210 path error checking, and if an error is detected, initializing the 1220 error recovery procedure. If no STP path error is detected, then the procedure stores the "incoming message command" time stamp from the message command into the time stamp data for the attached server 1230. The transmission procedure “XTP message response” is then performed to send a 1240 response message.

STC Control Message

[084] An STP control message (STC) command is used to request parameter updates from CTN, to establish and remove STP paths, and to read configuration information from attached servers. The “operation code” field in the message command specifies the operation to be performed.

[085] FIG. 13 depicts a command format representation of the STC message. The fields of this command format can be defined as follows:

• Message header 1310: The message header field contains information that depends on the type of data connection used to implement the STP connection.

• Command Code 1320: The command code field is defined with a defined value for STC message commands.

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-30 / 49- • Operation Code 1330: The operation code field contains a value that specifies the operation to be performed. Possible operations include:

o Update request operations • Change “stratum-1 request” setting o Read operations • Read Node Attachment Status • Read CTN Parameters o Notification operations • Establish STP path • Remove STP path • Set default mode control by the arbitrary server • Reset mode of control by the arbitrary server • State of control by the arbitrary server Active • CTN ID 1340: Contains the CTN ID of the sending server.

• Message command transmission time stamp 1350: It is set from the time of day (TOD) clock on the server when the message is transmitted along the STP path by the server.

• Message Receiving Command time stamp

1360: It is set to the time when the message command is received at the attached server. The field is defined from the time of day clock on the attached server when the message command is received. The moment the message command is transmitted, the field is undefined.

• Operation-dependent data 1370: This field contains data that depends on the operation code specified in the message command.

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-31 / 49Reply from STC message

[086] FIG. 14 depicts a representation of the response format of the STC message, where the format fields are defined as follows:

• Message header 1410 of the message: contains the message header field. The message header field contains information that depends on the type of data connection used to implement the STP connections.

• Response Code 1420: Contains the response code, which is an integer that describes the results of the attempt to execute the message command.

• CTN ID 1430: contains the CTN ID of the sending server.

• Response Transmission time stamp for message 1440:

It is set from the time of day clock of the server that sends the reply message the moment the reply of the message is transmitted.

• Message Reply Receiving time stamp

1450: Contains the Time Stamp from the moment the message response was received by the attached server. The field is defined from the time of day clock on the server that receives the reply message when the reply to the message is received.

• Operation Dependent Data 1460: This field contains data that depends on the operation code specified in the message command.

[087] As noted above, STC operations are specified by the operation code transmitted in each STC control message. The following types of operations are supported as described below: Update Request Operations; Reading operations; and Notification Operations.

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-32 / 49Update Request Operations

[088] An update request STP control message is sent by a secondary STP server to notify the active stratum-1 server of a CTN parameter update request. If the time server is directly attached to a layer-1 server, the secondary time server sends the message to the active layer-1 server. If the secondary time server is not directly attached to an active tier-1 server, the secondary time server sends the message to all attached servers that have a lower tier level.

[089] A secondary time server has the initiative to send an update request message upon receipt of a console command request to update a CTN parameter or upon receipt of an update request operation from another time server . When a secondary time server receives an update request message, it sends the update request parameter in the message to all attached servers with a lower tier level using a new update request message.

[090] Upon receiving an update request operation, the active layer-1 server performs the CTN parameter update procedure.

Change of Stratum-1 Request Configuration

[091] The “layer stratum-1” configuration change operation is issued by a secondary time server to request a stratum-1 configuration change for CTN. The operation is issued by a secondary time server after it has accepted a console command to modify the stratum-1 configuration for CTN. A secondary time server accepts the “modify layer-1” command only when the new layer-1 configuration specifies the secondary time server as the new

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-33 / 49estrato-1 active. The “operation dependent” area of ​​the message command is illustrated in FIG. 15.

• Stratum-1 Configuration Block 1500: Contains the new stratum-1 configuration that is being requested. The valid responses for the operation are as follows:

o Success: The command the message was successful.

o STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

o Busy: The message command cannot be executed at this time due to busy conditions or resource contention.

o Invalid Operation Parameters: The message command contains invalid parameters.

o Configuration error: The message command contains an incompatible CTN ID.

o Path Not Established: The path is not established on the attached server.

o CF response: Response codes indicate that the STP feature is not supported on the attached server.

[092] The "operation dependent" area of ​​the message response does not contain significant data.

Reading Operations

[093] Read commands are used to obtain CTN parameters and configuration information from attached servers. The data that can be obtained from an attached server includes: Node Attachment State; and CTN parameters.

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-34 / 49Read Node Attachment Status

[094] The “read node attach” status command returns the attach status to the node descriptor provided in the “operation dependent” area. Valid responses for this operation may also include:

o Success: The command the message was successful.

o STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

o Busy: The message command cannot be executed at this time due to busy conditions or resource contention.

o Invalid Operation Parameters: The message command contains invalid parameters.

o Configuration error: The message command contains an incompatible CTN ID.

o Path Not Established: The path is not established on the attached server.

o CF response: Response codes indicate that the STP feature is not supported on the attached server.

[095] When the response code is a particular value, the "operation dependent" area of ​​the message response may contain an attachment status request.

• Attachment State (A): Specifies the attachment state for the server described by the node descriptor provided in the message command. A first value indicates that the specified server is not attached to the message command receiver; and a second value indicates that the specified server is attached to the message command receiver.

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-35 / 49Read CTN Parameter

[096] The “read CTN parameter” operation reads the CTN parameters from the attached server. CTN parameters, which must be returned, are specified in the “operation dependent” area of ​​the message command. The “operation dependent” area of ​​the message command can include:

• CTN Parameter Code: Specifies the CTN parameters to be returned in the message response, for example:

o Read CTN General Parameters o Read New Stratum-1 Configuration Information o Read Time Zone Control Parameter Information Block (TCPIB) o Read Current Stratum-1 Confirmation Information

[097] Response codes valid for operations can be as follows:

o Success: The command the message was successful.

o STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

o Busy: The message command cannot be executed at this time due to busy conditions or resource contention.

o Invalid Operation Parameters: The message command contains invalid parameters.

o Configuration error: The message command contains an incompatible CTN ID.

o Path Not Established: The path is not established on the attached server.

o CF response: An indication that the STP facility is not supported on the attached server.

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-36 / 49 [098] When a particular response code is returned, the "operation dependent" area of ​​the message response block (in a representation) has the format illustrated in FIG. 16A.

• CTN 1610 Parameter Code: Specifies the CTN parameters that are provided in the message response, including:

o General CTN parameters provided in the message response.

o New Stratum-1 configuration information block provided in the message response.

the TCPIB provided in the message response.

o Current block of layer-1 configuration information provided in the message response.

• CTN 1620 Parameter Key: Contains the CTN parameter key for the server.

• CTN 1630 parameter data area: The content of the CTN parameter data area depends on the CTN parameter code in the message response, as shown in FIG. 16B.

• Correction Direction Information Block PRT (PCSIB) 1650: Contains the PCSIB for the server.

• New CTN ID Information Block (NCIIB) 1660: Contains the new CIIB for the server.

• Second Adjustment Compensation Information Block (LSOIB) 1670: Contains the LSOIB for the server and is used, for example, in the conversion between coordinated universal time (UTC) and STP time.

[099] New Stratum-1 configuration information data area:

• New Layer-1 Configuration Block: Contains the new layer-1 configuration block for the server.

[100] TCPIB data area:

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-37 / 49- • Time zone control parameter information block (TCPIB): Contains the TCPIB for the server.

[101] Current Stratum-1 Configuration Information Data Area:

• Layer-1 Configuration Block: Contains the current layer-1 configuration information block for the server.

Notification Operations

[102] Operations notification are used to create or remove a STP path and for communication between the alternate stratum-1 server and the arbitrary during a stratum-1 takeover.

Establish STP Path

[103] The STP path establishment (ESP) operation is performed as part of the STP path initialization procedure to establish a path between two servers. The operation is used to exchange and validate certain parameters associated with each of the attached servers. The "operation dependent" area of ​​the message command has, for example, the format illustrated in FIG. 17A.

• 1710 Connection Point Descriptor: Contains the CPC node descriptor of the server that sends the command.

• Stratum 1720: Contains the stratum of the server that sends the command.

• Maximum Version Number 1730: Specifies the highest STP version number supported by the installation of the STP that sends the command.

• Required Version Number 1740: Specifies the version number of the active STP in the STP installation that sends the command and is the version that must be used by the attached server for the ESP procedure to complete successfully. When not specified, the server that sends the

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-38 / 49command is capable of operating on any version up to and including the specified maximum version number.

• Stratum-1 Configuration Block 1750: Contains the stratum-1 configuration block for the server that sends the message command.

[104] The ESP message response block does not have any operation dependent data. The following responses are valid for the operation:

• Success: The message command was successful.

• STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

• Busy: The message command cannot be executed at this time due to busy conditions or resource constraints.

• Invalid Operation Parameters: The message command contains invalid parameters.

• Configuration error: The message command contains an incompatible CTN ID.

• Node Descriptor Error: The node descriptor in the ESP message command is invalid. The node descriptor value provided in the message command is stored in the connection information block on the receiving server.

• Unsupported Version: The version number required in the ESP message command is not supported by the receiving server. The required version number provided in the message command is stored in the connection information block on the receiving server.

• Tier 1 configuration error: The tier-1 configuration information block in the ESP message command is not compatible with the tier-1 configuration on the receiving server.

• Self-Coupled Server: The node descriptor of the attached server is identical to the node descriptor of that server, indicating that this server is coupled to itself.

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-39 / 49- • Active Assumption of Control State: The arbitrary server received an ESP command from the primary tier-1 server, while the arbitrary server was in the active acquisition state and the primary specified itself as the server active stratum-1.

• Permitted paths exceeded: The server cannot support any additional STP paths.

• CF response: Response codes indicate that the STP feature is not supported on the attached server.

Remove STP Path

[105] The operation of removing the STP path removes the established STP path to an attached server. The sending server sets the connection state of the path to not initialized as a result of the operation. The message command and the message response do not include any operation-dependent data. Valid responses for the operation include:

• Success: The message command was successful.

• STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

• Invalid Operation Parameters: The message command contains invalid parameters.

• Configuration error: The message command contains an incompatible CTN ID.

• Path Not Established: The path is not established on the attached server.

• CF Response: The response indicates that the STP feature is not supported on the attached server.

[106] The sending server defines the path state as uninitialized, and the reason for indicating "initialization not complete" as a result of the operation, regardless of the response.

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-40 / 49Set Acquisition Mode by the Arbitrary Server

[107] The acquisition mode operation by the arbitrary server is issued to the arbitrary server by the alternate stratum-1 server to put the arbitrary server in acquisition mode. The receiving server returns the arbitrary server acquisition status flag in the response block.

[108] The data area dependent on the message command operation has the format illustrated in FIG. 17B.

• 1780 active stratum-1 communication timeout: When set, the command to “set arbitrary server acquisition mode” is being issued because the inactive stratum-1 server has recognized a stratum-1 timeout condition active. When not defined, the message command "set arbitrary server acquisition mode" is being issued because the inactive tier-1 server has lost connection with the active tier-1 server.

[109] Response codes valid for the operation include:

o Success: The command the message was successful.

o STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

o Invalid Operation Parameters: The message command contains invalid parameters.

o Configuration error: The message command contains an incompatible CTN ID.

o Path Not Established: The path is not established on the attached server.

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-41 / 49o Invalid Command: The message command receiver is not an arbitrary designated server.

o Invalid Sender: The message command server is not an alternate tier-1 designated server.

o CF response: Response codes indicate that the STP feature is not supported on the attached server.

• Control Assumption State Flag 1790: When set, it indicates that the arbitrary server has entered control assumption mode and is in active control assumption state. When not defined, it indicates: that the arbitrary server has entered the takeover mode and is in the pending takeover state; or the arbitrary server did not go into takeover mode.

Reset Mode of Control by the Arbitrary Server

[110] The operation to reset the control-taking mode by the arbitrary server is issued to the arbitrary server by the alternate stratum-1 server to remove the arbitrary server from the control-taking mode. The operation-dependent area message command does not include any data. Valid responses for the operation include:

• Success: The message command was successful.

• STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

• Invalid Operation Parameters: The message command contains invalid parameters.

• Configuration error: The message command contains an incompatible CTN ID.

• Path Not Established: The path is not established on the attached server.

• Invalid Command: The message command receiver is not an arbitrary designated server.

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-42 / 49- • Invalid sender: The message command server is not an alternate tier-1 designated server.

• CF response: Response codes indicate that the STP feature is not supported on the attached server.

State of Assumption of Control by the Active Arbitrary Server

[111] The operation of "active state of control-taking by the arbitrary server" is issued to the alternate stratum-1 server by the arbitrary server to notify the alternate stratum-1 server that the arbitrary arbitrator server has entered the "assumption of control" state. active control ”. The operation-dependent area message command does not include any information. Valid responses for the operation include:

• Success: The message command was successful.

• STP Not Enabled: The STP feature is installed, but not enabled on the attached server.

• Invalid Operation Parameters: The message command contains invalid parameters.

• Configuration error: The message command contains an incompatible CTN ID.

• Path Not Established: The path is not established on the attached server.

• Invalid Command: The message command receiver is not an arbitrary designated server.

• Invalid sender: The message command server is not a designated server.

• CF response: Response codes indicate that the STP feature is not supported on the attached server.

[112] In a representation, one or more aspects of the present invention can be performed in a processing environment that is based on

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-43 / 49one architecture, which can be referred to as a native architecture, but which emulates the architecture of another, which can be referred to as a guest architecture. As examples, the native architecture is the Power4 or PowerPC ® architecture offered by International Business Machines Corporation, from Armonk, New York or an Intel ® architecture, offered by Intel Corporation; and the guest architecture is az / Architecture® also offered by International Business Machines Corporation, Armonk, New York. Aspects of z / Architecture® are described in “z / Architecture® Operating Principles”, IBM Publication No. SA22-7832-04, September 2005. In such an environment, instructions and / or logic, which is specified in z / Architecture® and designed to run on a z / Architecture® machine, is emulated to run in an architecture other than z / Architecture®. An example of this processing environment is described with reference to FIGS. 18-20.

[113] Referring to FIG. 18, a representation of the processing environment for incorporating and using one or more aspects of the present invention is described. The processing environment 1800 includes, for example, a native central processing unit 1802, a memory 1804 (for example, the main memory) and one or more input / output (I / O) devices 1806 coupled to another path, for example example, one or more 1808 buses and / or other connections. As an example, the 1800's processing environment may include a Power PC ® processor, a pSeries ® server or an xSeries ® server offered by International Business Machines Corporation, Armonk, New York; an HP Superdome with Intel ® Itanium ® 2 processors offered by Hewlett-Packard Company, Palo Alto, California; and / or other machines based on architectures offered by IBM ®, Hewlett-Packard, Intel ®, Sun Microsystems or others. Poder PC ®, pSeries ® and xSeries ® are registered trademarks of International Business Machines Corporation, Armonk, New York, USA. Intel ® and Itanium ® 2 are registered trademarks of Intel Corporation, Santa Clara, California.

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-44 / 49-

[114] The 1802 native central processing unit includes one or more 1810 native records, such as one or more general purpose records and / or one or more special purpose records, used during processing within the environment. These records include information that represents the state of the environment at any specific time in time.

[115] In addition, the 1802 native central processing unit executes instructions and code that are stored in memory 1804. In a specific example, the central processing unit executes the 1812 emulator code stored in 1804 memory. This code allows the processing environment configured in one architecture emulates the architecture of another. For example, the 1812 emulator code allows machines based on architectures other than z / Architecture®, such as Power PC® processors, pSeries® servers, xSeries® servers, HP Superdome® servers or others to emulate az / Architecture® and run the software and instructions developed based on z / Architecture®.

[116] Further details regarding the 1812 emulator code are described in relation to FIG. 19. 1902 guest instructions include software instructions (for example, machine instructions) that were developed to run on an architecture different from the 1802 native CPU (FIG. 18). For example, 1902 guest instructions may have been designed to run on the 902 z / Architecture® processor, but are instead being emulated on the 1802 native CPU (which may be, for example, an Intel® Itanium® 2 processor). In one example, the emulator code 1812 (FIG. 18) includes a routine search instruction 1900 to obtain one or more guest instructions 1902 from memory 1804, and optionally provide local security for the obtained instruction.

[117] Emulator code 1812 further includes a 1904 instruction translation routine to determine the type of guest instruction that was obtained and provide one or more native 1909 instructions that correspond to the guest instruction. In one example, provisioning includes creating during, for example, processing a translation, a native flow of instructions for

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-45 / 49a instruction from a certain guest. This includes identifying the function and creating the equivalent native instructions. In yet another example, providing native instructions includes selecting a code segment in the emulator associated with the guest instruction. For example, each guest instruction has an associated code segment in the emulator, which includes a sequence of one or more native instructions, and that code segment is selected to be executed.

[118] The 1812 emulator code also includes a 1906 emulation control routine to cause native instructions to be executed. The 1906 emulation control routine may cause the 1802 native CPU to execute a native instruction routine that emulates one or more previously obtained guest instructions and, upon completion of such execution, return control to the fetch routine instruction. to emulate obtaining the next guest instruction or guest instruction group. Execution of native instructions 1909 may include loading data into a 1804 memory register; storing data back into record memory; or perform some kind of arithmetic or logical operation, as determined by the translation routine. Each routine is, for example, implemented in the software, which is stored in memory and executed by the 1802 native central processing unit. In other examples, one or more routines or operations are implemented in the firmware, hardware, software or some combination of these. Emulated guest processor records can be emulated using 1810 records from the native CPU or using locations in memory 1804. In representations, guest instructions 1902, native instructions 1909 and emulation code 1812 can reside in the same memory or can be dispersed across different memory devices.

[119] In yet another representation, a suitable data processing system for storing and / or executing program code is usable that includes at least one processor coupled directly or indirectly to memory elements by means of a bus system. The memory elements include, for example, the local memory used during execution

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-46 / 49effective program code, mass storage and cache memory, which provide temporary storage of at least some program code to reduce the number of times that code must be retrieved from mass storage during execution.

[120] Input / Output or I / O devices (including, but not limited to keyboards, monitors, pointing devices, DASD, tape, CDs, DVDs, thumb drives and other memory media, etc.) can be attached to the system directly or through the intermediate I / O controllers. Network adapters can also be attached to the system to enable the data processing system to become attached to other data processing systems or remote printers or storage devices over private or public intermediary networks. Modems, cable modems, and Ethernet cards are just a few of the available types of network adapters.

[121] One or more aspects of the present invention can be included in an article of manufacture (for example, one or more computer program products), having, for example, the usable computer media. The medium has in it, for instance, logic or computer-readable program code means (for example, instructions, code, commands, etc.) to provide and facilitate the capabilities of the present invention. The article of manufacture can be included as part of a system (for example, the computer system) or sold separately.

[122] An example of an article of manufacture or a computer program product incorporating one or more aspects of the present invention is described with reference to FIG. 20. A computer program product 2000 includes, for example, one or more usable computer media 2002 for storing readable computer program code means or logic 2004 to offer and facilitate one or more aspects of the present invention. The medium may be a magnetic, optical, electromagnetic, infrared, or semiconductor (or apparatus or device) electronic system or a propagation medium. Examples of a computer-readable medium include a semiconductor or

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-47 / 49solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a hard magnetic disk and an optical disk. Examples of optical discs include read-only compact discs (CD-ROM), read / write compact discs (CD-R / W) and DVD.

[123] A sequence of program instructions or a logical set of one or more interrelated modules defined by one or more means of computer readable program codes means or logic directs the performance of one or more aspects of the present invention.

[124] Here are the features that facilitate the maintenance of time synchronization by multiple different computing systems to form a Coordinated Time Network. Servers on the time network take advantage of the Server Time Protocol to pass time information through high-speed data connections between systems that provide the ability for time clocks on each system to be synchronized with the accuracy required in today's high performance computing systems. The use of STP in high speed and low latency connections offers the ability to synchronize all systems in the CTN to accuracy, for example, a few microseconds when based on a reference time provided by a single server.

[125] STP provides the ability to define and maintain time stamp information within CTN, such as time zone, daylight saving time compensation and second adjustment compensation. The information can be updated within the scope of CTN in a programmed and coherent way, so that all changes occur at the same time on all CTN servers. This avoids potential system exposures to risks and interruptions that occur when these parameters are updated occasionally, creating discrepancies in the time setting between computers.

[126] CTN parameters can be defined and read by an operator through the STP console interface. CTN parameters include server connectivity, local time information, such as time zone and time

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-48 / 49summer and second adjustment compensation needed to calculate UTC. The console itself is an element that provides an operator interface for displaying and defining CTN parameters, and that is capable of communicating with the STP facility.

[127] Although one or more examples have been provided here, these are only examples. Many variations are possible without abandoning the spirit of the present invention. For example, processing environments other than the examples provided herein may include and / or benefit from one or more aspects of the present invention. For example. In addition, it is not necessary for the environment to be based on z / Architecture®, but instead it can be based on other architectures offered by, for example, IBM®, Intel®, Sun Microsystems, as well as others. In addition, the environment can include multiple processors, be shared and / or be coupled to other systems, as examples.

[128] In addition, although several control blocks have been described, each of these control blocks may include more, less and / or different information. The location within the control block and the size of each field within the control block can vary for different representations.

[129] As used here, the term "obtaining" includes, but is not limited to, seeking, receiving, possessing, supplying, being supplied, creating, developing, etc.

[130] Additional details on coordinated timing networks can be found in the following US patent applications: "TOD Clock System and Method for Clock Direction", Registration Application No. 11 / 223,886; “Synchronization Signal for Adjusting the Clock Direction of TOD”, Registration Application No. 11 / 532,168; "Managing access to data through a loop only if the blocking feature is modified", Registration Request No. 11 / 468,501; “Dispersion of the clock filter”, Registration Request n ° 11 / 223,878; “Method and System for Estimating Clock Deviations and Compensation”, Registration Application No. 11 / 223,876; “Use of Time Stamps T4 to Calculate Clock and Compensation Deviations”, Registration Application No. 11 / 223,577; “Direct acquisition by application programs of information usable in the

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-49 / 49determination of clock accuracy ”, Serial No. 11 / 450,025; “System and Method for Calibrating a TOD Watch”, Registration Application No. 11 / 223,642; “Method and system for establishing a logical path between servers in a coordinated time network”, by S. Carlson et al. Registration Application No. 60 / 887,576; and “Channel subsystem Channel subsystem Server time Protocol Protocol commands”, by S. Carlson et al, Registration Request No. 60 / 887,544.

[131] The capabilities of one or more aspects of the present invention can be implemented in software, firmware, hardware or some combination thereof. At least one machine-readable program storage device representing at least one machine-executable instruction program for executing the capabilities of the present invention can be provided.

[132] The flowcharts mentioned here are examples only. There can be many variations to these diagrams or the steps (or operations) described here without abandoning the spirit of invention. For example, steps can be performed in a different order, or steps can be added, deleted or modified. All of these variations are considered a part of the claimed invention.

[133] Although the representations have been illustrated and described here in detail, it will be apparent to those skilled in the relevant technique that various modifications, additions, substitutions and the like can be made without abandoning the spirit of the invention, and these are therefore considered within the scope of the invention defined in the claims.