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"Starter" HIS/VTAM IP-DLC/Enterprise Extender Notes RRS feed

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    "Starter" HIS/VTAM IP-DLC/Enterprise Extender Notes
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    The following text is designed to cover the "starter" topics which involve the Enterprise Extender logical connection between VTAM and HIS. HIS in this case is employing the IP-DLC link service in order to support the Enterprise Extender connection. The IP-DLC link service supports the implementation of an APPN end node, more strictly, an APPN branch network node (BNN) with a single "internal" "downstream" connection to a LEN node. DLUR also features in order to create one or more DLUR-DLUS logical connections in support of SSCP-dependent PUs and LUs.

    Details of the configuration of SSCP-independent LUs and SSCP-dependent PUs and LUs are not covered, neither in VTAM nor in HIS.

    Since this covers only "starter" topics, the configuration of "virtual routing nodes" in order to support a "connection network" is not covered.

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    The following are, in effect, sample z/OS Communications Server SNA component (VTAM) definitions.

    The statements shown and operands shown are those which are appropriate and sufficient. Further information on what they mean and what changes can be made can be found in the Communications Server (CS) SNA Resource Definition Reference manual backed up by descriptions in the CS SNA Network Implementation Guide manual. The necessary background will have come from education classes or self-study.

    All names (and numbers) need to be specified according to the VTAM naming convention within the installation. It should always be borne in mind that VTAM operates its own name space - which intersects with the SNA name space principally for LUs, but also including PUs and SSCPs (bearing in mind that a control point (CP) is also an LU in LEN and APPN). The VTAM name space is defined by those names which can appear as the value of the ID operand in a VARY, a MODIFY or a DISPLAY command.

    -

    The following are the required start options and an additional one, NODETYPE=NN, required in order to be an APPN network node. Being an APPN network node is a prerequisite to being able to play the role of a network node server (NNS) and, where SSCP-dependent LUs need to be supported, a dependent LU server (DLUS).

    NETID=name
    SSCPNAME=name
    SSCPID=number
    NODETYPE=NN

    If there are multiple CS IP names specified in BPXPARM, the TCPNAME= start option will be required - even if only one instance of CS IP is active.

    Assuming that the adjacent VTAM node, definitely playing the role of the network node server (NNS) if it is the only adjacent APPN network node but only possibly if there are multiple adjacent APPN network nodes, is also to play the role of the dependent LU server (DLUS), the value of the SSCPNAME start option corresponds to item 110 in the HIS configuration parameters.

    Note that the value of the NETID start option, the SNA network identifier, NetId, is expected to be the same throughout the configuration, the HIS LEN node, the HIS APPN node as implemented within the IP DLC link service logic, all VTAM nodes such as any adjacent APPN network nodes which could play the role of network node server (NNS) and any APPN network nodes which could play the role of dependent LU server (DLUS).

    Thus the value of the NETID start option corresponds to items 103 and 109 (and 203 and 402) in the HIS configuration parameters.

    It's a configuration possibility that, without the presence of border node capability, only adjacent APPN network nodes need to be configured with the same NetId but there is no particular benefit foreseen in a configuration involving HIS and its IP DLC link service where having different NetIds offers any benefits.

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    The following is a sample XCA major node for Enterprise Extender:

             VBUILD TYPE=XCA
    name     PORT  MEDIUM=HPRIP,                       enterprise extender *
                   HPREELIV=YES,             HPR liveness reduction for EE *
                   IPPORT=12000,                first of 5 IP port numbers *
                   IPRESOLV=0,                         no resolver timeout *
                   IPTOS=(20,40,80,C0,C0)              EE types of service
    name     GROUP IPADDR=aaa.aaa.aaa.aaa,    VIPA for enterprise extender *
                   AUTOGEN=(nn,prel,prep),  =< nn simultaneous connections *
                   ANSWER=ON,                   allow incoming connections *
                   CALL=INOUT,   use for outgoing and incoming connections *
                   DIAL=YES,                  switched procedures required *
                   DYNPU=YES,          dynamic link station control blocks *
                   KEEPACT=YES,     reactivate automatically after failure *
                   LIVTIME=(10,0),                  LDLC inoperative timer *
                   SRQRETRY=3,             short request timer retry count *
                   SRQTIME=15                 short request timer interval

    The value of the IPADDR operand corresponds to item 101 in the HIS configuration parameters.

    [A] An alternative pair of VTAM major nodes.

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    The following is a sample model major node with a DYNTYPE=EE PU statement model:

             VBUILD TYPE=MODEL
    EEMODEL  PU    DYNTYPE=EE,    Enterprise Extender dynamic link station *
                   CONNTYPE=APPN,                  APPN is to be supported *
                   CPCP=YES,                        request CP-CP sessions *
                   DISCNT=NO,                   no automatic disconnection *
                   DWINOP=NO,                   no reconnection after INOP *
                   DYNADJCP=YES,        accept adjacent node without check *
                   DYNLU=YES,                   dynamic creation of CDRSCs *
                   LIMRES=NO,          no automatic deactivation of LU 6.2 *
                   TGP=FASTENET         transmission group characteristics

    Note that the CONNTYPE, CPCP, DYNADJCP and DYNLU operand values can be obtained from the equivalent start options.

    Note also that there is a specification, DWINOP=NO, which implements a design principle that, following a failure, it is expected that the link station which establishes the connection initially is also to be responsible for re-establishing the connection.

    A glaring deficiency of HIS, verging on the fraudulent when the claim that the IP-DLC link service implements APPN is taken into account, is that transmission group (TG) characteristics cannot be specified. It appears possible that the following represents the values imposed on the HIS customer without the possibility, indeed the right, that any customer paying for an APPN implementation should have to be able to set these values for the purposes of exploiting APPN capabilities to the maximum:

    <quote>

    TG characteristics:
      Effective capacity                                    94 Mbits/s
      Connection cost                                       0
      Byte cost                                             0
      Security                                              No security
      Propagation delay                                     384 microseconds
      Modem class                                           0
      User-defined parameter 1                              128
      User-defined parameter 2                              128
      User-defined parameter 3                              128

    </quote>

    The closest set of TG characteristics to these using VTAM operands and values is the following:

    CAPACITY=100M
    COSTBYTE=0
    COSTTIME=0
    PDELAY=NEGLIGIB (.480 milliseconds)
    SECURITY=UNSECURE
    UPARM1=128
    UPARM2=128
    UPARM3=128

    This is implemented by the TG profile FASTENET.

    Since it is recommended that an APPN implementation should arrange for the TG characteristics to be the same in the direction A to B and the direction B to A over a connection, VTAM system programmers are given no option by Microsoft but to specify FASTENET as the TG profile - or the equivalent individual TG characteristics - for an Enterprise Extender logical connection where the Microsoft HIS IP DLC link service is the partner link station implementation. This is a most unsatisfactory situation which, unfortunately, Microsoft seems unable to get its collective head around!

    [A] An alternative pair of VTAM major nodes.

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    The following is a sample switched major node with a PU statement suitable for a logical connection supported by a DLUR-DLUS pair of LU type 6.2 sessions to an SSCP-dependent PU and following SSCP-dependent LUs where the DLUR function is responsible for establishing the logical connection:

             VBUILD TYPE=SWNET
    name     PU    IDBLK=xxx,               station identification - block *
                   IDNUM=xxxxx,            station identification - number *
                   ANS=CONT,                preserve sessions when no DLUS *
                   DISCNT=NO                    no automatic disconnection
    name     LU    LOCADDR=n                                 local address
    ...

    The value of the IDBLK operand corresponds to the leftmost field of item 112 in the HIS configuration parameters and the value of the IDNUM operand corresponds to the rightmost field of item 112 in the HIS configuration parameters.

    ---

    The following is an indication of the definitions required in the z/OS Communications Server IP component:

    1. A Static VIPA interface must be defined using a DEVICE statement, a LINK statement, an entry in the HOME statement list and possibly an entry in the BSDROUTINGPARMS/ENDBSDROUTINGPARMS block.

    Note: Suggestions that the entry in the HOME statement list must be positioned in a certain way derive from false information proffered at the time the Enterprise Extender function was introduced. The same goes for the suggestion that the IPCONFIG statement SOURCEVIPA parameter is required. It is not.

    The IP address of the static VIPA is the IP address specified by the GROUP statement in the Enterprise Extender GROUP statement.

    2. A "same host" (IUTSAMEH) interface must be defined using a DEVICE statement, a LINK statement, an entry in the HOME statement list and possibly an entry in the BSDROUTINGPARMS/ENDBSDROUTINGPARMS block. The name IUTSAMEH must also appear as the "device" name in a START command. Alternatively, and much more conveniently, the dynamic creation and activation of a "same host" interface using the IPCONFIG statement DYNAMICXCF parameter is possible and usually preferred.

    The IP addresses mentioned here will be those allocated by the IP naming and numbering authority in the installation according to local standards.

    Note that it is often the case that the VIPA is allocated from the same address range as applies to the interfaces to the LAN supported by OSA features using QDIO mode. In this way routing without a dynamic routing protocol being active and backup with a redundant OSA feature are possible.

    ---

    The following notes on configuration of the IP-DLC link service in HIS are based on Appendix C - Link and Connection References - in the "Configuring IP-DLC Link Service for IBM Enterprise Extender White Paper" together with a pair of "blog" entries from Stephen Jackson.

    http://www.microsoft.com/download/en/details.aspx?displaylang=en&=tm&id=17441

    http://blogs.msdn.com/b/sjackson/archive/2008/12/31/additional-details-about-the-ip-dlc-link-service-advanced-prop

    erty-settings.aspx

    http://blogs.msdn.com/b/sjackson/archive/2009/01/30/ip-dlc-connection-and-dlur-retry-limits.aspx

    Although sought, no other online sources of information could be found which offered any more information than the above.

    Just to be really sure since Stephen Jackson said that the "white paper" is not the only source of information - in a rather tentative manner:

    <quote>

    Does it provide the only or best ways to configure, check, or validate the mainframe settings, probably not.

    /quote>

    I downloaded all 10M of the HIS 2010 help, HIS2010Help_chm.exe. What a waste of time! It is only a copy of what you can find online and what is online is certainly not as comprehensive as the "white paper". Stephen Jackson is hoist with his own petard! And I have no compunctions about being rude since his indolence and lack of candour in coming clean over this has wasted my time!

    Incidentally, there is a total disconnection in these help pages between the section "Sample Host Definitions" and the rest of the pages. The so-called "Sample Host Definitions" take us gently through "Token Ring", "SDLC" and "X.25" but with nary a mention of "IP-DLC"! Of course, they are all completely atrophied and nobody in Microsoft seems to care!

    There is a summary of the prompts in hierarchical sequence followed by notes. Note that the references follow four sequences:

    101 and so on indicate the *required* parameters. This may be regarded as the "Getting Started" set.
    201 and so on represent additional specifications relating to backup resources.
    301 and so on are for modifying default operational parameter values. This may be regarded as the "tuning" set.
    401 and so on represent alternatives.

    -

    HIS 2006 Link Service Configuration

     General Tab
      Service name: SNAIP1
      Service title: IP-DLC Link Services #1
      Primary NNS: [101]
      Backup NNS: [201]
      No preferred NNS [301]
      Local address
       Adapter address:
       Static IP address:
      Local APPN node [102]
       Network name: [103]
       Control point name: [104]
       Use Dynamic PU Definition [105]
       Node ID: [401]
      Associated LEN node: [106]

     Advanced tab [302]
      IP-DLC timeouts
       Receive ACK: [303]
       Livetime: [304]
       Maximum CMD retransmissions: [305]
      Maximum BTU size
       Send: [306]
       Receive: [307]
      HPR/IP activation retries [308]
       Infinite
       Limited:
       Delay between retries:

    -

    HIS 2006 Connection Configuration - for SSCP-independent LUs

     General tab
      Name: INDPEER
      Link service: SNAIP1
      Comment:
      Remote end: Peer system [107]

    -

    HIS 2006 Connection Configuration - for SSCP-dependent LUs

     General tab
      Name: IPDLC
      Link service: SNAIP1
      Comment:
      Remote end: Host system [107]
      Allowed directions: Outgoing calls
      Activation: On server startup
      Affiliate application: <None>

     Address tab
      Primary DLUS [108]
       Network name: [109]
       Control point name: [110]
      Backup DLUS [202]
       Network name: [203]
       Control point name: [204]
      Preferred routing node [309]
       Address:
       Network name:
       Control point name:

     System Identification tab
      Local node name [111]
       Network name: [402]
       Control point name: [403]
       Local node ID: [112]
      Link compression: None

     IP DLC tab [310]
      Connection retry limits [311]
       Unlimited
       Limited:
       Delay after retry:
      DLUR retry limits [312]
       No retries
       Unlimited
       Limited:
       Delay after retry:

    --

    [101] Primary NNS:

    This is the IP address - or a name which the name server system will convert to an IP address - of a partner system over the IP-DLC or Enterprise Extender link.

    [201] Backup NNS:

    This is the IP address - or a name which the name server system will convert to an IP address - of a partner system over the IP-DLC or Enterprise Extender link.

    [101] and [201]: Because the APPN node supported by the IP-DLC link service is an APPN end node with respect to the Enterprise Extender link, it is likely to very likely that the adjacent nodes will be APPN network nodes. Furthermore is will probably be desirable that an adjacent network node should be capable of supplying "network node services". This explains why the HIS prompts make a series of assumptions and imply that they will always be network node servers but, in the words of "Sportin' Life", "It ain't necessarily so!".

    [301] No preferred NNS

    If either of the identified adjacent APPN nodes capable of being a network node server is acceptable, there will be no need, following a failure of the "primary NNS" and having switched to the "backup NNS" for "network node services" to switch back to the "primary NNS" when the "primary NNS" makes contact again.

    [102] Local APPN Node

    The IP-DLC link service is rather more than purely a link service such as previous "link services" used by HIS. It is the implementation of an APPN node, specifically an APPN Branch Network Node (BNN). Being the implementation of a BNN it presents the appearance of an APPN end node on "upstream" links, which are the Enterprise Extender links, and the appearance of an APPN network node on "downstream" links. There is only one "downstream" link, it is internal to the supporting Windows machine and it connects in a logical manner to the main HIS component, the "SNA Service", which is elsewhere identified as a Low Entry Networking (LEN) node.

    [103] Network name:

    This is the SNA network identifier (NetId) which is used to "qualify" any LU names associated with the APPN node.

    [104] Control point name:

    This is the control point name, an LU name, which, when "qualified" by the NetId uniquely identifies the APPN node.

    [105] Use Dynamic PU Definition

    This is a very poorly described option. When selected it causes the "Node ID" fields to be "grayed out". It can only be guessed that the option has been provided in order to avoid unnecessary definition when VTAM has been defined in such a way that it will not require an unique node identification field to be presented in the XID associated with establishing the Enterprise Extender link. This can be either because the PU statement used in order to define the adjacent link station characteristics is either defined - actually statically defined, but uses the control point name as a means of identification, or really is defined dynamically, typically using adjacent link station characteristics specified in a model PU statement with DYNTYPE=EE, as is permitted by the DYNPU=YES specification of the GROUP statement in the TYPE=XCA major node.

    [401] Node ID:

    If "Use Dynamic PU Definition" has *not* been selected, these two fields may be used in order to define the node identification which is carried in the XID associated with establishing the Enterprise Extender link. The PU statement used in order to define the adjacent link station characteristics is actually defined and uses the IDBLK and IDNUM operand values as the means of identification.

    [106] Associated LEN node:

    This names the "SNA Service" implementation of a LEN node to be associated with the IP-DLC link service APPN node.

    [302] Advanced tab

    There is almost certainly no need to change any of the parameters set under this tab initially. They may be changed subsequently as a matter of "fine tuning" when the principles behind them as, for example, laid out in RFC 2353, "APPN/HPR in IP Networks" are thoroughly understood. Also any such changes will probably be in conjunction with the equivalent parameters in the partner link station.

    [303] Receive ACK:

    This sets the value of the short request timer in milliseconds. The equivalent parameter in VTAM is the value of the SRQTIME operand of the Enterprise Extender GROUP statement. The default value is 15 000.

    [304] Livetime:

    This sets the value of the "logical data link control" (LDLC) "liveness" timer in milliseconds. The "liveness" timer controls the connection assurance mechanism when there is no other traffic. The equivalent parameter in VTAM is the current value of parameter initialised and controlled by the suboperands of the LIVTIME operand of the Enterprise Extender GROUP statement. The default value is 10 000.
     
    [305] Maximum CMD retransmissions:

    This sets the value of the short request retry count. The equivalent parameter in VTAM is the value of the SRQRETRY operand of the Enterprise Extender GROUP statement. The default value is 3.

    [306] Send:

    This specifies the maximum size of the basic transmission unit (BTU) outbound, sent. The default value is 1493, with a minimum determined by HPR architecture of 768 and a maximum of 4096.

    [307] Receive:

    This specifies the maximum size of the BTU inbound, received. The default value is 1493, with a minimum determined by HPR architecture of 768 and a maximum of 4096.

    HPR/IP activation retries [308]

    While attempting to establish an Enterprise Extender, "IP DLC" or, as also known, "HPR/IP" logical connection over the IP network, the parameters that can be set are to continue retrying indefinitely, "infinite", or for a "limited" number of times and a delay value can also be specified. The default is "limited" with 10 retries and the default delay is 25 seconds.

    [107] Remote end:

    It is a requirement always to create a "connection configuration" with a "remote end" specified as "Peer system". When the associated link service is the IP-DLC link service, this is sufficient for the definition and support of SSCP-independent LUs. If SSCP-dependent LUs need to be defined and supported, a "connection configuration" with a "remote end" specified as "Host system" must be created.

    Note that "connection configuration" with a "remote end" specified as "Peer system" when the associated link service is the IP-DLC link service, requires no further parameters to be defined.

    [108] Primary DLUS

    The dependent LU server (DLUS) is a VTAM network node which supports a pair of SSCP-independent LU type 6.2 sessions to the dependent LU requester (DLUR) function supported by the IP-DLC link service APPN node. If SSCP-dependent LU resources are to be supported by the IP-DLC link service and the associated "SNA Service", this is required as the definition of a fully-qualified control point name. In fact, the VTAM control point is also Known as the system services control point (SSCP) and so the VTAM control point name is also the SSCP name.

    [109] Network name:

    This is the NetId which is used to "qualify" the primary DLUS SSCP name. It is the value of the NETID VTAM start option.

    [110] Control point name:

    This is the SSCP name of the primary DLUS. It is the value of the SSCPNAME VTAM start option.

    [202] Backup DLUS

    A backup for DLUS may optionally be specified.

    [203] Network name:

    This is the NetId which is used to "qualify" the backup DLUS SSCP name. It is the value of the NETID VTAM start option.

    [204] Control point name:

    This is the SSCP name of the backup DLUS. It is the value of the SSCPNAME VTAM start option.

    [309] Preferred routing node

    This is a most peculiar specification which has nothing whatsoever directly to do with APPN architecture. It may be that, having considered that the specification of transmission group characteristics is too complicated a feature of APPN for Microsoft customers to be expected to be able to comprehend, poor lambs, Microsoft developers then found that actually there is a particular circumstance where tinkering with the APPN route selection mechanism is needed. Since no details are provided - although this is an excellent opportunity for Stephen Jackson to come up with yet another "blog" article - no more can be said at present. I just hope it does what it says "on the box".

    The specification is optional and, initially anyhow, should be avoided, possibly permanently!

    [111] Local node name

    The following fields are to be used in order to provide a means whereby the a PU statement and following LU statements, corresponding to an SSCP-dependent PU and related SSCP-dependent LUs, can be located in a switched major node. Since the support of the SSCP-dependent resources is over a DLUR-DLUS logical connection and the connected SSCP-dependent resources appear to be resident in the same node as that which supports the DLUR function, this appears to be an instance of "internal" DLUR, node identification fields, identified as the "local node ID", is the least confusing method to use.

    Nevertheless it should be noted that, although *apparently* an instance of "internal" DLUR, architecturally, the SSCP-dependent resources are resident in an adjacent node to that which supports the DLUR function, and so this is actually an instance of "external" DLUR. However the connection between the node supporting the DLUR function and the node supporting the SSCP-dependent resources is internal to the supporting Windows machine.

    [402] Network name:

    This is the NetId which is used to "qualify" the control point name.

    [403] Control point name:

    This is the control point name which may optionally be used to identify the node supporting SSCP-dependent resources and supported by DLUR. Its use, having limited architectural logic in this HIS context is not recommended.

    [112] Local node ID:

    This is the node identification which may optionally be used to identify the node supporting SSCP-dependent resources and supported by DLUR. Its use in the context of an instance of actually or apparently "internal" DLUR is conventional and hence recommended.

    The first field corresponds to the IDBLK operand of the PU statement and the second field corresponds to the IDNUM operand of the PU statement.

    [310] IP DLC tab

    There is almost certainly no need to change any of the parameters set under this tab initially. They may be changed subsequently as a matter of "fine tuning" when the principles behind them are understood.

    The title of the tab is also rather curious given that the parameters are associated with the DLUR-DLUS logical connection, a function not necessarily limited in general to "IP DLC".

    [311] Connection retry limits

    The parameters that can be set to continue retrying initially to create a DLUR-DLUS logical connection are indefinitely, "unlimited", or for a "limited" number of times and a delay value can also be specified. The default is "limited" with 8 retries and the default delay is 10 seconds.

    [312] DLUR retry limits

    Following a failure of the DLUR-DLUS logical connection, the parameters that can be set are not to retry recreating a DLUR-DLUS logical connection, "no retries", to continue retrying indefinitely, "unlimited", or for a "limited" number of times and a delay value can also be specified. The default is "limited" with 8 retries and the DEfault delay is 10 seconds.

    ---

    [A] It may be that not using the functions associated with the AUTOGEN operand and the DYNPU=YES specification is Preferred. Note that these two changes are quite independent.

    Thus the following is an alternative sample XCA major node for Enterprise Extender where only one Enterprise extender connection is required and hence only one pair of LINE and PU statements is specified after the GROUP Statement:

             VBUILD TYPE=XCA
    name     PORT  MEDIUM=HPRIP,                       enterprise extender *
                   HPREELIV=YES,             HPR liveness reduction for EE *
                   IPPORT=12000,                first of 5 IP port numbers *
                   IPRESOLV=0,                         no resolver timeout *
                   IPTOS=(20,40,80,C0,C0)              EE types of service
    name     GROUP IPADDR=aaa.aaa.aaa.aaa,    VIPA for enterprise extender *
                   DIAL=YES,                  switched procedures required *
                   DYNPU=NO,        no dynamic link station control blocks *
                   LIVTIME=(10,0),                  LDLC inoperative timer *
                   SRQRETRY=3,             short request timer retry count *
                   SRQTIME=15                 short request timer interval
    name     LINE  ANSWER=ON,                   allow incoming connections *
                   CALL=INOUT,   use for outgoing and incoming connections *
                   KEEPACT=YES      reactivate automatically after failure
    name     PU

    The following is a sample switched major node with a PU statement suitable for an Enterprise Extender logical connection. Recognition is based on the control point name necessarily specified for the APPN node implemented in this case by the HIS IP-DLC link service. It is a replacement for the sample model major node.

             VBUILD TYPE=MODEL
    EEMODEL  PU    CPNAME=name,                         control point name *
                   CONNTYPE=APPN,                  APPN is to be supported *
                   CPCP=YES,                        request CP-CP sessions *
                   DISCNT=NO,                   no automatic disconnection *
                   DWINOP=NO,                   no reconnection after INOP *
                   DYNADJCP=YES,        accept adjacent node without check *
                   DYNLU=YES,                   dynamic creation of CDRSCs *
                   LIMRES=NO,          no automatic deactivation of LU 6.2 *
                   TGP=FASTENET         transmission group characteristics

    The control point name, the value of the CPNAME operand, corresponds to item 104 in the HIS configuration Parameters.

    Note that the NetId could also be represented using the NETID operand but, where the NetId is that assigned to VTAM, there is no need for the NETID operand.

    ---

    Tuesday, June 28, 2011 8:37 PM

Answers

All replies

  • Thanks for the information.
    Stephen Jackson - MSFT
    Friday, July 15, 2011 2:35 AM
  • Since I received a note regarding the "Starter ...", I reviewed it and found one major error - very near the end in my alternatives - and a few infelicities. Since there was such a possibility for confusion, this is a complete repeat but only what was supposed to be a switched major node sample is significantly different from what I posted before.

    Does nobody - with one exception obviously - *read* my posts?

    "Starter" HIS/VTAM IP-DLC/Enterprise Extender Notes
    ---------------------------------------------------

    The following text is designed to cover the "starter" topics which involve the Enterprise Extender logical connection between VTAM and HIS. HIS in this case is employing the IP-DLC link service in order to support the Enterprise Extender connection. The IP-DLC link service supports the implementation of an APPN end node, more strictly, an APPN branch network node (BNN) with a single "internal" "downstream" connection to a LEN node. DLUR also features in order to create one or more DLUR-DLUS logical connections in support of SSCP-dependent PUs and LUs.

    Details of the configuration of SSCP-independent LUs and SSCP-dependent PUs and LUs are not covered, neither in VTAM nor in HIS.

    Since this covers only "starter" topics, the configuration of "virtual routing nodes" in order to support a "connection network" is not covered.

    ---

    The following are, in effect, sample z/OS Communications Server SNA component (VTAM) definitions.

    The statements shown and operands shown are those which are appropriate and sufficient. Further information on what they mean and what changes can be made can be found in the Communications Server (CS) SNA Resource Definition Reference manual backed up by descriptions in the CS SNA Network Implementation Guide manual. The necessary background will have come from education classes or self-study.

    All names (and numbers) need to be specified according to the VTAM naming convention within the installation. It should always be borne in mind that VTAM operates its own name space - which intersects with the SNA name space principally for LUs, but also including PUs and SSCPs (bearing in mind that a control point (CP) is also an LU in LEN and APPN). The VTAM name space is defined by those names which can appear as the value of the ID operand in a VARY, a MODIFY or a DISPLAY command.

    -

    The following are the required start options and an additional one, NODETYPE=NN, required in order to be an APPN network node. Being an APPN network node is a prerequisite to being able to play the role of a network node server (NNS) and, where SSCP-dependent LUs need to be supported, a dependent LU server (DLUS).

    NETID=name
    SSCPNAME=name
    SSCPID=number
    NODETYPE=NN

    If there are multiple CS IP names specified in BPXPARM, the TCPNAME= start option will be required - even if only one instance of CS IP is active.

    Assuming that the adjacent VTAM node, definitely playing the role of the network node server (NNS) if it is the only adjacent APPN network node but only possibly if there are multiple adjacent APPN network nodes, is also to play the role of the dependent LU server (DLUS), the value of the SSCPNAME start option corresponds to item 110 in the HIS configuration parameters.

    Note that the value of the NETID start option, the SNA network identifier, NetId, is expected to be the same throughout the configuration, the HIS LEN node, the HIS APPN node as implemented within the IP DLC link service logic, all VTAM nodes such as any adjacent APPN network nodes which could play the role of network node server (NNS) and any APPN network nodes which could play the role of dependent LU server (DLUS).

    Thus the value of the NETID start option corresponds to items 103 and 109 (and 203 and 402) in the HIS configuration parameters.

    It's a configuration possibility that, without the presence of border node capability, only adjacent APPN network nodes need to be configured with the same NetId but there is no particular benefit foreseen in a configuration involving HIS and its IP DLC link service where having different NetIds offers any benefits.

    -

    The following is a sample XCA major node for Enterprise Extender:

             VBUILD TYPE=XCA
    name     PORT  MEDIUM=HPRIP,                       enterprise extender *
                   HPREELIV=YES,             HPR liveness reduction for EE *
                   IPPORT=12000,                first of 5 IP port numbers *
                   IPRESOLV=0,                         no resolver timeout *
                   IPTOS=(20,40,80,C0,C0)              EE types of service
    name     GROUP IPADDR=aaa.aaa.aaa.aaa,    VIPA for enterprise extender *
                   AUTOGEN=(nn,prel,prep),  =< nn simultaneous connections *
                   ANSWER=ON,                   allow incoming connections *
                   CALL=INOUT,   use for outgoing and incoming connections *
                   DIAL=YES,                  switched procedures required *
                   DYNPU=YES,          dynamic link station control blocks *
                   KEEPACT=YES,     reactivate automatically after failure *
                   LIVTIME=(10,0),                  LDLC inoperative timer *
                   SRQRETRY=3,             short request timer retry count *
                   SRQTIME=15                 short request timer interval

    The value of the IPADDR operand corresponds to item 101 in the HIS configuration parameters.

    [A] An alternative pair of VTAM major nodes.

    -

    The following is a sample model major node with a DYNTYPE=EE PU statement model:

             VBUILD TYPE=MODEL
    EEMODEL  PU    DYNTYPE=EE,    Enterprise Extender dynamic link station *
                   CONNTYPE=APPN,                  APPN is to be supported *
                   CPCP=YES,                        request CP-CP sessions *
                   DISCNT=NO,                   no automatic disconnection *
                   DWINOP=NO,                   no reconnection after INOP *
                   DYNADJCP=YES,        accept adjacent node without check *
                   DYNLU=YES,                   dynamic creation of CDRSCs *
                   LIMRES=NO,          no automatic deactivation of LU 6.2 *
                   TGP=FASTENET         transmission group characteristics

    Note that the CONNTYPE, CPCP, DYNADJCP and DYNLU operand values can be obtained from the equivalent start options.

    Note also that there is a specification, DWINOP=NO, which implements a design principle that, following a failure, it is expected that the link station which establishes the connection initially is also to be responsible for re-establishing the connection.

    A glaring deficiency of HIS, verging on the fraudulent when the claim that the IP-DLC link service implements APPN is taken into account, is that transmission group (TG) characteristics cannot be specified. It appears possible that the following represents the values imposed on the HIS customer without the possibility, indeed the right, that any customer paying for an APPN implementation should have to be able to set these values for the purposes of exploiting APPN capabilities to the maximum:

    <quote>

    TG characteristics:
      Effective capacity                                    94 Mbits/s
      Connection cost                                       0
      Byte cost                                             0
      Security                                              No security
      Propagation delay                                     384 microseconds
      Modem class                                           0
      User-defined parameter 1                              128
      User-defined parameter 2                              128
      User-defined parameter 3                              128

    </quote>

    The closest set of TG characteristics to these using VTAM operands and values is the following:

    CAPACITY=100M
    COSTBYTE=0
    COSTTIME=0
    PDELAY=NEGLIGIB (.480 milliseconds)
    SECURITY=UNSECURE
    UPARM1=128
    UPARM2=128
    UPARM3=128

    This is implemented by the TG profile FASTENET.

    Since it is recommended that an APPN implementation should arrange for the TG characteristics to be the same in the direction A to B and the direction B to A over a connection, VTAM system programmers are given no option by Microsoft but to specify FASTENET as the TG profile - or the equivalent individual TG characteristics - for an Enterprise Extender logical connection where the Microsoft HIS IP DLC link service is the partner link station implementation. This is a most unsatisfactory situation which, unfortunately, Microsoft seems unable to get its collective head around!

    [A] An alternative pair of VTAM major nodes.

    -

    The following is a sample switched major node with a PU statement suitable for a logical connection supported by a DLUR-DLUS pair of LU type 6.2 sessions to an SSCP-dependent PU and following SSCP-dependent LUs where the DLUR function is responsible for establishing the logical connection:

             VBUILD TYPE=SWNET
    name     PU    IDBLK=xxx,               station identification - block *
                   IDNUM=xxxxx,            station identification - number *
                   ANS=CONT,                preserve sessions when no DLUS *
                   DISCNT=NO                    no automatic disconnection
    name     LU    LOCADDR=n                                 local address
    ...

    The value of the IDBLK operand corresponds to the leftmost field of item 112 in the HIS configuration parameters and the value of the IDNUM operand corresponds to the rightmost field of item 112 in the HIS configuration parameters.

    ---

    The following is an indication of the definitions required in the z/OS Communications Server IP component:

    1. A Static VIPA interface must be defined using a DEVICE statement, a LINK statement, an entry in the HOME statement list and possibly an entry in the BSDROUTINGPARMS/ENDBSDROUTINGPARMS block.

    Note: Suggestions that the entry in the HOME statement list must be positioned in a certain way derive from false information proffered at the time the Enterprise Extender function was introduced. The same goes for the suggestion that the IPCONFIG statement SOURCEVIPA parameter is required. It is not.

    The IP address of the static VIPA is the IP address specified by the GROUP statement in the Enterprise Extender GROUP statement.

    2. A "same host" (IUTSAMEH) interface must be defined using a DEVICE statement, a LINK statement, an entry in the HOME statement list and possibly an entry in the BSDROUTINGPARMS/ENDBSDROUTINGPARMS block. The name IUTSAMEH must also appear as the "device" name in a START command. Alternatively, and much more conveniently, the dynamic creation and activation of a "same host" interface using the IPCONFIG statement DYNAMICXCF parameter is possible and usually preferred.

    The IP addresses mentioned here will be those allocated by the IP naming and numbering authority in the installation according to local standards.

    Note that it is often the case that the VIPA is allocated from the same address range as applies to the interfaces to the LAN supported by OSA features using QDIO mode. In this way routing without a dynamic routing protocol being active and backup with a redundant OSA feature are possible.

    ---

    The following notes on configuration of the IP-DLC link service in HIS are based on Appendix C - Link and Connection References - in the "Configuring IP-DLC Link Service for IBM Enterprise Extender White Paper" together with a pair of "blog" entries from Stephen Jackson.

    http://www.microsoft.com/download/en/details.aspx?displaylang=en&=tm&id=17441

    http://blogs.msdn.com/b/sjackson/archive/2008/12/31/additional-details-about-the-ip-dlc-link-service-advanced-property-settings.aspx

    http://blogs.msdn.com/b/sjackson/archive/2009/01/30/ip-dlc-connection-and-dlur-retry-limits.aspx

    Although sought, no other online sources of information could be found which offered any more information than the above.

    Just to be really sure since Stephen Jackson said that the "white paper" is not the only source of information - in a rather tentative manner:

    <quote>

    Does it provide the only or best ways to configure, check, or validate the mainframe settings, probably not.

    /quote>

    I downloaded all 10M of the HIS 2010 help, HIS2010Help_chm.exe. What a waste of time! It is only a copy of what you can find online and what is online is certainly not as comprehensive as the "white paper". Stephen Jackson is hoist with his own petard! And I have no compunctions about being rude since his indolence and lack of candour in coming clean over this has wasted my time!

    Incidentally, there is a total disconnection in these help pages between the section "Sample Host Definitions" and the rest of the pages. The so-called "Sample Host Definitions" take us gently through "Token Ring", "SDLC" and "X.25" but with nary a mention of "IP-DLC"! Of course, they are all completely atrophied and nobody in Microsoft seems to care!

    There is a summary of the prompts in hierarchical sequence followed by notes. Note that the references follow four sequences:

    101 and so on indicate the *required* parameters. This may be regarded as the "Getting Started" set.
    201 and so on represent additional specifications relating to backup resources.
    301 and so on are for modifying default operational parameter values. This may be regarded as the "tuning" set.
    401 and so on represent alternatives.

    -

    HIS 2006 Link Service Configuration

     General Tab
      Service name: SNAIP1
      Service title: IP-DLC Link Services #1
      Primary NNS: [101]
      Backup NNS: [201]
      No preferred NNS [301]
      Local address
       Adapter address:
       Static IP address:
      Local APPN node [102]
       Network name: [103]
       Control point name: [104]
       Use Dynamic PU Definition [105]
       Node ID: [401]
      Associated LEN node: [106]

     Advanced tab [302]
      IP-DLC timeouts
       Receive ACK: [303]
       Livetime: [304]
       Maximum CMD retransmissions: [305]
      Maximum BTU size
       Send: [306]
       Receive: [307]
      HPR/IP activation retries [308]
       Infinite
       Limited:
       Delay between retries:

    -

    HIS 2006 Connection Configuration - for SSCP-independent LUs

     General tab
      Name: INDPEER
      Link service: SNAIP1
      Comment:
      Remote end: Peer system [107]

    -

    HIS 2006 Connection Configuration - for SSCP-dependent LUs

     General tab
      Name: IPDLC
      Link service: SNAIP1
      Comment:
      Remote end: Host system [107]
      Allowed directions: Outgoing calls
      Activation: On server startup
      Affiliate application: <None>

     Address tab
      Primary DLUS [108]
       Network name: [109]
       Control point name: [110]
      Backup DLUS [202]
       Network name: [203]
       Control point name: [204]
      Preferred routing node [309]
       Address:
       Network name:
       Control point name:

     System Identification tab
      Local node name [111]
       Network name: [402]
       Control point name: [403]
       Local node ID: [112]
      Link compression: None

     IP DLC tab [310]
      Connection retry limits [311]
       Unlimited
       Limited:
       Delay after retry:
      DLUR retry limits [312]
       No retries
       Unlimited
       Limited:
       Delay after retry:

    --

    [101] Primary NNS:

    This is the IP address - or a name which the name server system will convert to an IP address - of a partner system over the IP-DLC or Enterprise Extender link.

    [201] Backup NNS:

    This is the IP address - or a name which the name server system will convert to an IP address - of a partner system over the IP-DLC or Enterprise Extender link.

    [101] and [201]: Because the APPN node supported by the IP-DLC link service is an APPN end node with respect to the Enterprise Extender link, it is likely to very likely that the adjacent nodes will be APPN network nodes. Furthermore it will probably be desirable that an adjacent network node should be capable of supplying "network node services". This explains why the HIS prompts make a series of assumptions and imply that they will always be network node servers but, in the words of "Sportin' Life", "It ain't necessarily so!".

    [301] No preferred NNS

    If either of the identified adjacent APPN nodes capable of being a network node server is acceptable, there will be no need, following a failure of the "primary NNS" and having switched to the "backup NNS" for "network node services" to switch back to the "primary NNS" when the "primary NNS" makes contact again.

    [102] Local APPN Node

    The IP-DLC link service is rather more than purely a link service such as previous "link services" used by HIS. It is the implementation of an APPN node, specifically an APPN Branch Network Node (BNN). Being the implementation of a BNN it presents the appearance of an APPN end node on "upstream" links, which are the Enterprise Extender links, and the appearance of an APPN network node on "downstream" links. There is only one "downstream" link, it is internal to the supporting Windows machine and it connects in a logical manner to the main HIS component, the "SNA Service", which is elsewhere identified as a Low Entry Networking (LEN) node.

    [103] Network name:

    This is the SNA network identifier (NetId) which is used to "qualify" any LU names associated with the APPN node.

    [104] Control point name:

    This is the control point name, an LU name, which, when "qualified" by the NetId uniquely identifies the APPN node.

    [105] Use Dynamic PU Definition

    This is a very poorly described option. When selected it causes the "Node ID" fields to be "grayed out". It can only be guessed that the option has been provided in order to avoid unnecessary definition when VTAM has been defined in such a way that it will not require an unique node identification field to be presented in the XID associated with establishing the Enterprise Extender link. This can be either because the PU statement used in order to define the adjacent link station characteristics is either defined - actually statically defined, but uses the control point name as a means of identification, or really is defined dynamically, typically using adjacent link station characteristics specified in a model PU statement with DYNTYPE=EE, as is permitted by the DYNPU=YES specification of the GROUP statement in the TYPE=XCA major node.

    [401] Node ID:

    If "Use Dynamic PU Definition" has *not* been selected, these two fields may be used in order to define the node identification which is carried in the XID associated with establishing the Enterprise Extender link. The PU statement used in order to define the adjacent link station characteristics is actually defined and uses the IDBLK and IDNUM operand values as the means of identification.

    [106] Associated LEN node:

    This names the "SNA Service" implementation of a LEN node to be associated with the IP-DLC link service APPN node.

    [302] Advanced tab

    There is almost certainly no need to change any of the parameters set under this tab initially. They may be changed subsequently as a matter of "fine tuning" when the principles behind them as, for example, laid out in RFC 2353, "APPN/HPR in IP Networks" are thoroughly understood. Also any such changes will probably be in conjunction with the equivalent parameters in the partner link station.

    [303] Receive ACK:

    This sets the value of the short request timer in milliseconds. The equivalent parameter in VTAM is the value of the SRQTIME operand of the Enterprise Extender GROUP statement. The default value is 15 000.

    [304] Livetime:

    This sets the value of the "logical data link control" (LDLC) "liveness" timer in milliseconds. The "liveness" timer controls the connection assurance mechanism when there is no other traffic. The equivalent parameter in VTAM is the current value of parameter initialised and controlled by the suboperands of the LIVTIME operand of the Enterprise Extender GROUP statement. The default value is 10 000.
     
    [305] Maximum CMD retransmissions:

    This sets the value of the short request retry count. The equivalent parameter in VTAM is the value of the SRQRETRY operand of the Enterprise Extender GROUP statement. The default value is 3.

    [306] Send:

    This specifies the maximum size of the basic transmission unit (BTU) outbound, sent. The default value is 1493, with a minimum determined by HPR architecture of 768 and a maximum of 4096.

    [307] Receive:

    This specifies the maximum size of the BTU inbound, received. The default value is 1493, with a minimum determined by HPR architecture of 768 and a maximum of 4096.

    [308] HPR/IP activation retries

    While attempting to establish an Enterprise Extender, "IP DLC" or, as also known, "HPR/IP" logical connection over the IP network, the parameters that can be set are to continue retrying indefinitely, "infinite", or for a "limited" number of times and a delay value can also be specified. The default is "limited" with 10 retries and the default delay is 25 seconds.

    [107] Remote end:

    It is a requirement always to create a "connection configuration" with a "remote end" specified as "Peer system". When the associated link service is the IP-DLC link service, this is sufficient for the definition and support of SSCP-independent LUs. If SSCP-dependent LUs need to be defined and supported, a "connection configuration" with a "remote end" specified as "Host system" must be created.

    Note that "connection configuration" with a "remote end" specified as "Peer system" when the associated link service is the IP-DLC link service, requires no further parameters to be defined.

    [108] Primary DLUS

    The dependent LU server (DLUS) is a VTAM network node which supports a pair of SSCP-independent LU type 6.2 sessions to the dependent LU requester (DLUR) function supported by the IP-DLC link service APPN node. If SSCP-dependent LU resources are to be supported by the IP-DLC link service and the associated "SNA Service", this is required as the definition of a fully-qualified control point name. In fact, the VTAM control point is also known as the system services control point (SSCP) and so the VTAM control point name is also the SSCP name.

    [109] Network name:

    This is the NetId which is used to "qualify" the primary DLUS SSCP name. It is the value of the NETID VTAM start option.

    [110] Control point name:

    This is the SSCP name of the primary DLUS. It is the value of the SSCPNAME VTAM start option.

    [202] Backup DLUS

    A backup for DLUS may optionally be specified.

    [203] Network name:

    This is the NetId which is used to "qualify" the backup DLUS SSCP name. It is the value of the NETID VTAM start option.

    [204] Control point name:

    This is the SSCP name of the backup DLUS. It is the value of the SSCPNAME VTAM start option.

    [309] Preferred routing node

    This is a most peculiar specification which has nothing whatsoever directly to do with APPN architecture. It may be that, having considered that the specification of transmission group characteristics is too complicated a feature of APPN for Microsoft customers to be expected to be able to comprehend, poor lambs, Microsoft developers then found that actually there is a particular circumstance where tinkering with the APPN route selection mechanism is needed. Since no details are provided - although this is an excellent opportunity for Stephen Jackson to come up with yet another "blog" article - no more can be said at present. I just hope it does what it says "on the box".

    The specification is optional and, initially anyhow, should be avoided, possibly permanently!

    [111] Local node name

    The following fields are to be used in order to provide a means whereby a PU statement and following LU statements, corresponding to an SSCP-dependent PU and related SSCP-dependent LUs, can be located in a switched major node. Since the support of the SSCP-dependent resources is over a DLUR-DLUS logical connection and the connected SSCP-dependent resources appear to be resident in the same node as that which supports the DLUR function, this appears to be an instance of "internal" DLUR, node identification fields, identified as the "local node ID", is the least confusing method to use.

    Nevertheless it should be noted that, although *apparently* an instance of "internal" DLUR, architecturally, the SSCP-dependent resources are resident in an adjacent node to that which supports the DLUR function, and so this is actually an instance of "external" DLUR. However the connection between the node supporting the DLUR function and the node supporting the SSCP-dependent resources is internal to the supporting Windows machine.

    [402] Network name:

    This is the NetId which is used to "qualify" the control point name.

    [403] Control point name:

    This is the control point name which may optionally be used to identify the node supporting SSCP-dependent resources and supported by DLUR. Its use, having limited architectural logic in this HIS context is not recommended.

    [112] Local node ID:

    This is the node identification which may optionally be used to identify the node supporting SSCP-dependent resources and supported by DLUR. Its use in the context of an instance of actually or apparently "internal" DLUR is conventional and hence recommended.

    The first field corresponds to the IDBLK operand of the PU statement and the second field corresponds to the IDNUM operand of the PU statement.

    [310] IP DLC tab

    There is almost certainly no need to change any of the parameters set under this tab initially. They may be changed subsequently as a matter of "fine tuning" when the principles behind them are understood.

    The title of the tab is also rather curious given that the parameters are associated with the DLUR-DLUS logical connection, a function not necessarily limited in general to "IP DLC".

    [311] Connection retry limits

    The parameters that can be set to continue retrying initially to create a DLUR-DLUS logical connection are indefinitely, "unlimited", or for a "limited" number of times and a delay value can also be specified. The default is "limited" with 8 retries and the default delay is 10 seconds.

    [312] DLUR retry limits

    Following a failure of the DLUR-DLUS logical connection, the parameters that can be set are not to retry recreating a DLUR-DLUS logical connection, "no retries", to continue retrying indefinitely, "unlimited", or for a "limited" number of times and a delay value can also be specified. The default is "limited" with 8 retries and the default delay is 10 seconds.

    ---

    [A] It may be that not using the functions associated with the AUTOGEN operand and the DYNPU=YES specification is preferred. Note that these two changes are quite independent.

    Thus the following is an alternative sample XCA major node for Enterprise Extender where only one Enterprise Extender connection is required and hence only one pair of LINE and PU statements is specified after the GROUP Statement:

             VBUILD TYPE=XCA
    name     PORT  MEDIUM=HPRIP,                       enterprise extender *
                   HPREELIV=YES,             HPR liveness reduction for EE *
                   IPPORT=12000,                first of 5 IP port numbers *
                   IPRESOLV=0,                         no resolver timeout *
                   IPTOS=(20,40,80,C0,C0)              EE types of service
    name     GROUP IPADDR=aaa.aaa.aaa.aaa,    VIPA for enterprise extender *
                   DIAL=YES,                  switched procedures required *
                   DYNPU=NO,        no dynamic link station control blocks *
                   LIVTIME=(10,0),                  LDLC inoperative timer *
                   SRQRETRY=3,             short request timer retry count *
                   SRQTIME=15                 short request timer interval
    name     LINE  ANSWER=ON,                   allow incoming connections *
                   CALL=INOUT,   use for outgoing and incoming connections *
                   KEEPACT=YES      reactivate automatically after failure
    name     PU

    The following is a sample switched major node with a PU statement suitable for an Enterprise Extender logical connection. Recognition is based on the control point name necessarily specified for the APPN node implemented in this case by the HIS IP-DLC link service. It is a replacement for the sample model major node.

             VBUILD TYPE=SWNET
    name     PU    CPNAME=name,                         control point name *
                   CONNTYPE=APPN,                  APPN is to be supported *
                   CPCP=YES,                        request CP-CP sessions *
                   DISCNT=NO,                   no automatic disconnection *
                   DWINOP=NO,                   no reconnection after INOP *
                   DYNADJCP=YES,        accept adjacent node without check *
                   DYNLU=YES,                   dynamic creation of CDRSCs *
                   LIMRES=NO,          no automatic deactivation of LU 6.2 *
                   TGP=FASTENET         transmission group characteristics

    The control point name, the value of the CPNAME operand, corresponds to item 104 in the HIS configuration Parameters.

    Note that the NetId could also be represented using the NETID operand but, where the NetId is that assigned to VTAM, there is no need for the NETID operand.
    Monday, October 24, 2011 1:54 AM