Abstract:
A method and apparatus for creating a unique identification for each stack in partitions of a host data computer such that a plurality of partitions may share a single adapter card during an Input/Output operation wherein the adapter card is exchanging data between the host and a Local Area Network. The adapter card includes a unique identifier pool for maintaining values of unique identifiers which are available for identifying the stacks. The method and apparatus also provides that a deleted unique identifier for a stack may be reused by newly created stacks and may be reassigned to a recreated stack, if still available, when the stack had previously been deleted by the operating system, but is then recreated.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention is related to the transfer of data in an environment using Operating System (OS) stacks wherein the data transfer is between LAN devices or clients and the OS stack via an adapter wherein each OS stack has a unique identifier, as is more particularly related to an apparatus and method for assigning a unique identifier to each OS stack such that the OS stacks may be shared by an adapter.  
           [0002]    Operating System (OS) stacks are established to enable Input/Output (I/O) transfer of data by Logical Partitions (LPARs) established in the host of a data processing system. When data in received from or sent to a Local Area Network (LAN), the data is transmitted through an adapter which is connected between the host and the LAN. Typically, every adapter must have a unique Media Access Control (MAC) address per OS stack attached to it. In Operating Systems, such as the z/OS operating system available from IBM, thousands of LPARs may exist at one time, with each LPAR possibly having one or more OS stacks. However, it is not feasible to provide an adapter for each of these OS stacks. Thus, it is necessary to find a way to assign a plurality of OS stacks to a single adapter. However the addressing scheme of the present Internet Protocol version 4 (IPv4) has a limited number of available addresses which may be assigned.  
           [0003]    Internet Protocol Version 6 (IPv6) is the next generation protocol designed by the Internet Engineering Task Force to replace the current version IPv4. Most of today&#39;s internet uses IPv4, which is now nearly twenty years old. IPv4 has been remarkably resilient in spite of its age, but it is beginning to have problems. Most importantly, there is a growing shortage of IPv4 addresses, which are needed by all new machines added to the Internet.  
           [0004]    IPv6 fixes a number of problems in IPv4, such as the limited number of available IPv4 addresses. It also adds many improvements to IPv4 in areas such as routing, network autoconfiguration, expanded addressing capabilities, header format simplification, improved support for extensions and options, flow labeling capability, and consolidated authentication and privacy capabilities.  
           [0005]    The merits of IPv6 can be summarized as follows:  
           [0006]    scalability: IPv6 uses 128 bit address space. Address length is 4 times longer than IPv4.  
           [0007]    security: IPv6 basic specification includes security. It includes packet encryption (ESP:Encapslated Security Payload) and source authentication (AH:Authentication Header).  
           [0008]    real-time: To support real-time traffic such as video conference, IPv6 has “Flow Label”. Using flow label, router can know which end-to-end flow a packet belongs to, and then find out the packet which belongs to real-time traffic.  
           [0009]    autoconfiguration: IPv6 basic specification includes address autoconfiguration. So, even novice users can connect their machines to network.  
           [0010]    specification optimization: IPv6 succeeds good parts and discards old and useless parts of IPv4.  
           [0011]    IPv4 addresses are grouped into 5 classes. Class A, B, and C, addresses support unicast communication. Class D addresses support IP multicasting. Class E addresses are experimental. IPv4 addresses are 32 bit in length and follow the convention provided in the Table 1.  
                       TABLE 1                       Class   Range   Type                   A   0.0.0.0 to           B   127.255.255.255   unicast       C   128.0.0.0 to           191.255.255.255           192.0.0.0 to           223.255.255.255       D   224.0.0.0 to   multicast           239.255.255.255       H   240.0.0.0 to   experimental           247.255.255.255                  
 
           [0012]    IPv6 addresses are 128 bits in length and have the format shown in Table 2 for a unicast address.  
                                                       TABLE 2                       3 bits   13 bits   8 bits   24 bits   16 bits   64 bits                   FP   TLA   Res   NLA   SLA   Interface ID           ID       ID   ID                                                                       Where               FP   Format Prefix (001)           TLA ID   Top-Level Aggregation Identifier           RES   Reserved for future use           NLA ID   Next-Level Aggregation Identifier           SLA ID   Site-Level Aggregation Identifier          
 
           [0013]    INTERFACE ID Interface Identifier  
         SUMMARY OF THE INVENTION  
         [0014]    It is an object of the present invention to provide a method and apparatus for assigning a unique identifier to each OS stack which is used in a logical partition of a host computer which communicates with a LAN client through an open source adapter.  
           [0015]    It is a further object of the present invention to provide an open source adapter with a unique identifier pool and a method and apparatus to add the unique identifier of an OS stack to the identifier pool.  
           [0016]    It is a further object of the present invention to provide a method and apparatus wherein a command to the open source adapter causes the adapter to generate the unique identifier of an OS stack.  
           [0017]    It is also an object of the present invention to provide a method and apparatus wherein a command to the open source adapter causes the adapter to remove a unique identifier of an OS stack from the unique identifier pool of the adapter such that the unique identifiers may be reused.  
           [0018]    It is also an object of the present invention to provide a method and apparatus wherein an OS stack may request that it be given a specific unique identifier.  
           [0019]    It is a further object of the present invention to provide a method and apparatus wherein the unique identifier of an OS stack includes a unique identifier to the MAC address of the adapter. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    These and other objects will be apparent to one skilled in the art from the following detailed description of the invention taken in conjunction with the accompanying drawings in which:  
         [0021]    [0021]FIG. 1 is a schematic diagram of a data processing system in which applications in LPARs of a host computer exchanges data with LAN clients via an open source adapter which has a unique identifier pool in which are registered unique identifiers of the OS stack of each application;  
         [0022]    [0022]FIG. 2 is diagrammatic illustration of the initialization flow of messages sent between an application wishing to initiate a data transfer wherein a unique identifier is established and data transfer is accomplished;  
         [0023]    [0023]FIG. 3 is a diagrammatic illustration of a CREATEADDR request sent to the open source adapter to establish the unique identifier for an OS stack;  
         [0024]    [0024]FIG. 4 is a diagrammatic illustration of a CREATEADDR reply wherein the open source adapter returns the assigned unique identifier to the OS stack;  
         [0025]    [0025]FIG. 5 is a diagrammatic illustration of a DESTROYADDR request sent to the open source adapter to destroy the unique identifier such that the unique identifier may be reused; and  
         [0026]    [0026]FIG. 6 is a diagrammatic illustration of a DESTROYADDR reply wherein the open source adapter replies that the unique identifier has been deleted from the unique identifier pool. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]    [0027]FIG. 1 is a schematic diagram of a data processing system  100  having a host computer A  102  having a processor  150  and a memory  152 . As is well understood, the memory  152  contains computer coding which is executable by the processor  150 , and may include, for instance, operating systems and applications for processing data. The computer executable code may be understood as having a plurality of layers. Two layers are shown in FIG. 1, the Logical Partition (LPAR) layer  103 , and the VTAM layer  104 . The LPAR layer  103  is shown having a plurality of LPARs  105  shown as LPAR 1 -LPARn. Each LPAR  105  may support one or more applications, which each application having its own identification. For instance, LPAR 1  has two applications, App 1   106  and App 2   107 , with each application having an identification id 1  and id 2 , respectively. When an application in an LPAR wishes to communicate, the Operating System establishes an OS stack. In LPAR 1 , App 1   106  has an OS stack OS 1   110 , and App 2   107  has OS stack OS 2   112 , while in LPAR 2 , applications App 3  and App 4  share the OS stack OS 3 . It thus will be understood that each application may have its own OS stack, or that it may share an OS stack with another application.  
         [0028]    The Virtual Telecommunications Access Method (VTAM) layer  103  provides telecommunication access by applications in the host by issuing instructions, as understood by those skilled in the art. The VTAM layer  104  communicates with an Open Source Adapter (OSA)  115  which is a computer card controlling communications between the applications in the host  102  and a Local Area Network (LAN)  120 . The LAN  120  is connected to clients  122  with which applications in the host  101  may exchange data. The OSA  115  includes a unique identifier pool  125  in which is stored the unique identifiers of the OS stacks established by the operating system for the applications in the LPAR layer  103 . The unique identifiers are assigned to the OS stacks by the OSA  115 , as will be explained. The unique identifiers are forwarded by the OSA  115  over the LAN to clients  122  such that clients may communicate with the applications, as is well known. Part of the unique identifier is the MAC address for the OSA  115 , and part of the identifier is a unique extension assigned by the OSA  115  to designate only one OS stack, such that many OS stacks and thus many applications may share connections to the LAN  120  via a single OSA  115 .  
         [0029]    The IPv6 standard defines a mechanism to assign addresses to interfaces that uses an IEEE 48 bit MAC identifier. Every card or adapter must have a unique mac address per OS stack attached to it. For sharing between OS stacks or LPARs, a mechanism is provided to uniquely generate addresses for a particular interface. A new set of commands is introduced that uniquely manages a set of 64K unique values to combine with the local 48 bit MAC to form a unique 64 bit identifier for each OS Stack. In addition, a mechanism and algorithm is provided to assign a stack with a consistent address set that does not jeopardize the uniqueness of the generated identifiers.  
         [0030]    The OSA card  115  manages a 64K bit string that represents 1 of 64K unique identifiers. Every time an OS stack activates the adapter, a CREATEADDR command is generated and sent to the OSA card  115 . The OSA card  115  then searches the unique identifier pool  125  to find the next available bit. The OSA  115  then returns that identifier to the requesting stack. The returned 16 bit identifier is then combined with the 48 bit MAC addresses of the OSA card  115  to provide a totally unique addresses to represent this application address on the IPv6 network. The mixing of the returned identifier and MAC address is OS dependent. It can place the 16 bits in any bit position of the 64 bit identifier to generate the unique identifier. Each time an OS stack deactivates the adapter, a DESTROYADDR command is issued thus returning the saved identifier to the pool of available values. If an OS stack reactivates the adapte,r the OS stack may try to retrieve its previous idenfier so that the OS stack retains the same IPv6 addresses for this adapter. If the OS stack has another active interface onto the same LAN, the OS stack can provide fault tolerance for these IPv6 addresses across the deactivation and subsequent reactivation of the adapter. This retrieving of an old identifier is done by putting the last 64 bit identifier that the OS stack used into the CREATEADDR identifier field. If the old value is still unassigned, it will be returned to the OS stack, and the reassigned identifier will then be marked unavailable on the OSA bit mask. Thus through this central identifier pool  125 , many OS applications (in a single or multiple LPAR system) can share the same adapter on the IPv6 network.  
         [0031]    The OSA  115  is allowed to reuse and share the same unique identifier for fault tolerance reasons. Each back-end application can be mapped into a common identifier so that in the case of a node failure, another node can take over in a seamless transition to the end user. Since the OSA  115  is common to the user applications, it can assure that a unique identifier is selected for each application (not simply an LPAR identifier since there can be thousands of unique addresses in a singular LPAR) all sharing a single 48 bit MAC address.  
         [0032]    [0032]FIG. 2 is an illustration of the initialization flow for initiating a data transfer between an application and a LAN client  122 . Using, for instance, the Transmission Control Protocol/Internet Protocol(TCP/IP) protocols, at  201  a STRTLAN.request is sent to the OSA  115  to tell the card that a new OS stack is available. In response, a STARTLAN.reply is returned. At  202 , a QIPASST.request is sent to the OSA  115  to determine what function is available. In response, a QUIPASST.reply is returned. At  203 , a SETASSPARMS.request is sent to the OSA  115  card to start IPv6 support. In response, a SETASSPARMS.reply is sent. At  204 , a CREATEADDR.request is sent to the OSA card  115  to get a unique identifier assigned to the new OS stack. At this point, the OSA  115  searches the Unique Identifier Pool  125  to determine the next available value to be used as the unique identifier for the new OS stack. A CREATEADDR.reply is returned containing the unique identifier as shown in FIG. 4. At  205 , the Application Setup is completed and the OSA card  115  returns a reply to indicate the setup. It will be understood that the setup is dependent on the operating system being used, the particular application, and the perhaps the LAN clients  122  involved. At  206 , the data transfer between the application and the client begins and continues until completed.  
         [0033]    [0033]FIG. 3 is a diagram of the CREATEADDR.request sent at  204 . It will be noted that an identifier  301  may be included if the OS stack wishes to use a previous unique identifier. FIG. 4 is a diagram of the CREATEADDR.reply sent by the OSA  115  is response to the CREATEADDR.request. The unique identifier  401  for the OS stack will be included. If the requested identifier  301  is available, the unique identifier  401  will be the same as the requested identifier  301 . If the requested identifier  301  is not available, the unique identifier  401  will be the next available value as determined by the OSA  115 .  
         [0034]    [0034]FIG. 5 is a diagram of the DESTROYADDR.request sent to the OSA  115  by the operating system if an OS stack is removed. The DESTROYADDR.request includes the unique identifier value  501  to be deleted. FIG. 6 is a diagram of the DESTROYADDR.reply sent in response to the DESTROYADDR.request. The unique identifier  601  in the DESTROYADDR.reply is the value of the unique identifier that was deleted. The deleted unique identifier  601  will then be made available for the next CREATEADDR.request received by the OSA  115 .  
         [0035]    While the preferred embodiment of the invention has been illustrated and described herein, it is to be understood that the invention is not limited to the precise construction herein disclosed, and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.