Subject: I-D ACTION:draft-ietf-tn3270e-service-loc-00.txt

From: [email-masked]
Date: Thu, 21 May 1998 09:40:10 -0400

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Telnet TN3270 Enhancements Working Group of the IETF.

        Title           : TN3270E Service Location and Session Balancing
        Author(s)       : G. Ledford, J. Naugle, K. Kasthurirangan
        Filename        : draft-ietf-tn3270e-service-loc-00.txt
        Pages           : 17
        Date            : 20-May-98

   This document discusses the implementation of Service Location
   Protocol and session balancing with a TN3270E emulator in a client
   server implementation with a TN3270E server.

   Application program developer's can locate TN3270E services and
   load balance among those services (3270 host sessions), by using
   this Service Location Protocol support.

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---

From: Anne Child <[email-masked]>
Date: Tue, 26 May 98 09:30:39 -0500

All-
    Attached is a copy of the draft with my comments.
    -Anne Child
     [email-masked]
______________________________ Reply Separator _________________________________
Subject: I-D ACTION:draft-ietf-tn3270e-service-loc-00.txt
Author:  [email-masked]
Date:    5/21/98 8:40 AM

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Telnet TN3270 Enhancements Working Group of the
 IETF.

        Africa: ftp.is.co.za

        Europe: ftp.nordu.net
                ftp.nis.garr.it

Below is the data which will enable a MIME compliant mail reader
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Internet-Draft.
<< My interspersed comments are all preceeded with "<<".
<< General comments:
<< 1. In the draft you refer to TN3270 not TN3270E.  It seems that this
<<    specification could be applied to both a TN3270 and TN3270E server.
<<    Indeed, we implemented the same code for both TN3270 and TN3270E on
<<    the client side.  So you could just eliminate the "E" altogether.
<<    Or am I thinking of it backwards... TN3270E encompasses TN3270?  Now,
<<    then it seems unlikely that a server vendor would bother to implement
<<    Service Location without implementing TN3270E also.
<< 2. Is there a difference between "Session Balancing" and "Load Balancing"?
<<    I ponder that one if from the client's perspective and the other from
<<    the server's perspecitve.  But is it's one and the same, then maybe
<<    only one term should be used.  I know it seems redundant at times but
<<    it makes sure you are perfectly clear.  At least make sure you are using
<<    "load" where it makes sense and "session" where it makes sense.

TN3270E Working Group                                          Jim Naugle
Internet Draft:                                     Kashturi Kasthurangan
<draft-ietf-tn3270e-service-loc-00.txt>                               IBM
Expiration Date: November 98                                Gregg Ledford
                                                       Zephyr Development
                                                                   May 98

           TN3270E Service Location and Session Balancing
             draft-ietf-tn3270e-service-loc-00.txt

Status of This Memo

   This document is an Internet Draft.  Internet Drafts are working
   documents of the Internet Engineering Task Force (IETF), its Areas,
   and its Working Groups.  Note that other groups may also distribute
   working documents as Internet Drafts.

   Internet Drafts are draft documents valid for a maximum of six
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   Please check the I-D abstract listing contained in each Internet
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   Draft.  Distribution of this document is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

Abstract

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Internet Draft   TN3270E Service Location/Session Balancing   May 1998

1. Table of Contents

Status of This Memo
Abstract
 1. Table of Contents
 2. Introduction
 3. Overview of RFC 2165
     3.1 SLP Agents
     3.2 SLP Relationships
<<   3.2 Service Agents
     3.3 User Agents
     3.4 SLP Relationships
 4. TN3270E Server Environment and Load
     4.1 TN3270E Server Load
 5. TN3270E Client Configuration
     5.1 SLP Scope
     5.2 Directory Agent Discovery Time-out
     5.3 Service Agent Multicast Time-out
 6. Service Registration and Service Templates
<< 7. TN3270E Client Implementation Information
     7.1 Overview
     7.2 How to Obtain List of TN3270E Servers Supporting SLP
     7.3 TN3270E Sample Client Flow
        7.3.1 Open the SLP connection
        7.3.2 Query the list of TN3270E servers
        7.3.3 Determine loading of each TN3270E server
<<      7.3.4 Closing the SLP connection
<< This does not exist
<<      7.3.5 Freeing memory structures
<< This does not exist
     7.4 Recommendations
 8. Sample Trace Flow of SLP and Session Balancing
<< 9. Service Registration Messages and Service Templates
10. References
<<11. Authors' Addresses

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2. Introduction

   This document will provide information on Service Location Protocol
   implementation to discover TN3270E servers in a network and session
   balance among those servers.  The implementation follows the
   standards track RFC 2165, Service Location Protocol [1].

3. An overview of RFC 2165

   RFC 2165, Service Location Protocol (SLP) [1], provides an automatic
   way for clients to discover services within an administrative
   domain.

   These services have various attributes associated with them from
   which a client can base a service selection on.
<< delete "on"
The basic design involves the use of three agent types.  These are: User      Agents (UA's), Service Agents (SA's) and Directory Agents (DA's).

3.1 SLP Agents

   User Agents are used to query Service Agents or Directory Agents.
   They acquire/request service information based upon the desired
   attributes and service needed for the user application.

   Service Agents represent a specific service and advertise service
   information.

   Directory Agents act as a central collection point for service
   registration information by Service Agents which is later requested
   by "user agents" in "intranets".

3.2 Service Agents

   The Service Agent is defined as a  process working on  behalf of one
   or more services to advertise service information. Service
   information is a collection of attributes and configuration
   information associated with a single service.  The Service Agents
   advertise service information for either one or a collection of
   service instances. The service itself is a process or system
   providing a facility to the network, which in our case would be the
   TN3270 server.

   The service registers itself with the service agent so that the SA
   can start advertising this information over the network. The process
   of registrations
<< delete last "s"
                     consists of the service giving the SA all relevant
   configuration information and attributes. The format of this
   information is called the Service template. The service template for
   TN3270 which is given below contains the URL which is the address of

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   the server with the port, which should be used to connect to it. The
   URL also contains the service type which in this case is TN3270. The
   template also contains all the other attributes of the service like
   scope, load etc.

3.3 User Agents
   The User Agent working on the TN3270 client's behalf retrieves
   service information from the Service Agent or a Directory Agent and
   based on the required attributes decides to connect or not with a
   particular server.
<< The User Agent does not decide, the TN3270 client or even the end
<< user decides which server to connect to based upon the gathered
<< information.  So you could change it to "The User Agent working on
<< the TN3270 client's behalf retrieves service information from the
<< Service Agent(s) or a Directory Agent.  Based on the gathered information
<< and required attributes the TN3270 client or user can decide whether
<< or not to connect with a particular server.
                    Based on the service advertisements from various
   TN3270 servers, the client looks at the load attribute and can
   decide to connect to the least loaded server. If by the time it
   connects to that particular TN3270 server the server becomes
   unavailable it can try connecting to the next server in its list
   (ie: the second least loaded server whose advertisement was
   retrieved by the client/user agent).

3.4 SLP Relationships
   The diagram below taken from RFC 2165 [1] helps illustrate the agent
   relationships described above.

      +---------------+   we want this info:     +-----------+
      |  Application  | - - - - - - - - - - - -> |  Service  |
      +---------------+                          +-----------+
           /|\                                      |     |
            |                         +-------------+     |
            |                         |                   |
           \|/                       \|/                 \|/
      +---------------+          +-----------+      +----------------+
      |   User Agent  |<-------->|  Service  |      |    Service     |
      +---------------+          |   Agent   |      | Agent which    |
            |                    +-----------+      | does not reply |
            |                         |             | to UA requests |
            |                        \|/            +----------------+
            |                   +-------------+           |
            +------------------>|  Directory  |<----------+
                                |    Agent    |
                                +-------------+      ___________
                                     /|\            / Many other\
                                      +------------>|   SA's    |
                                                    \___________/

4. TN3270E Server Environment and Load

   TN3270E Servers are pervasive in today's networked environment.  SLP
   provides emulator clients with a way to discover TN3270E servers in
   the network and session balance among the servers.  The TN3270E
   servers could be distributed across different SNA gateways with

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Internet Draft   TN3270E Service Location/Session Balancing   May 1998

   different connection methods to hosts.  The use of LU pools provides
   a easy way for administrators to provide users access to hosts.
   Administrators can add users to LU pools that have pre-configured
   LU's with specific attributes, like LU types and model types.

   These LU pools would typically have LUs from several different
   gateways assigned, and as members of the LU pool make TN3270E
   session connections, they would be making connections to different
   TN3270E servers, with different load factors, so that session
   balancing could be accomplished. The use of LU pools is not a
   requirement for SLP and session balancing.  A TN3270E client could
   obtain a session by using SLP and session balancing to locate the
   least loaded server in the network.  On a service request a wild
   card "*" could be used when asking for LUPOOL if the emulator
   doesn't care which device types are supported in given pools or if
   it can assume given pools support only certain device types.
   (LUPOOL=xyz\t*)

4.1 TN3270E Server Load

   TN3270E servers providing load information, typically will include
   number of sessions available, not in current use,  as part of the
   calculation in determining load for that server. There can be other
   factors that might have an effect on server load.  For example, if a
   server is not dedicated to only SNA traffic, and is handling other
   processes, like file services and print services, etc.  It is beyond
   the scope of this document to discuss how individual server load
   calculations should be determined.

   If the TN3270E server coexists in a network with other TN server
   implementations using SLP for load  balancing, TN3270E server load
   could be adjusted to compensate for differences in load
   calculations.

   One way to allow TN3270E server administrators to compensate for
   differences in implementations of calculating server load
   measurement is to provide the ability to modify the load calculation
   on the TN3270E server.  An element of control can be provided by
   allowing the administrator to modify the load measurement, by using
   an integral number between 0 and 100 (100 being the highest) to
   change the load. This load measurement acts as an additional factor
   on the server's actual load calculation, so that the administrator
   could bias up or down, the likelihood of that server being selected
   by a TN3270E client.

   Load is defined as one of the attributes for the TN3270E server.  If
   a UA provides only a Service Type, in an Attribute Request,  then
   the reply includes all attributes and all values for that Service

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   Type, and Load would be included.  Attribute Requests can include a
   select clause, so you could just be returned information on load for
   each server.  For more information on Attribute Requests refer to
   Service Location Protocol Internet draft [4].
<< Do you want to refer to the new draft [4] or the original [1]?

   An application could issue a  SL_GetService
<< I can't find this call in the current API for Service Location [2].
<< They have all new calls and GetService isn't one of them.  You may
<< want to use "An API for Service Location  <draft-ietf-srvloc-api-01.txt"
<< from March 24, 1997 instead.  The same applies to all your other
<< "SL_..." references from here on.  All the calls in the new API doc are
<< "SLP..." not "SL_...".
                                               request to locate a
   TN3270E server. Then an application designed to perform least-load
   location of  a TN3270E service, could issue a series of SL_GetAttrs
   calls directed to each URL to obtain the load measurement of each
   server.  It would specify a select clause similar to the one below
   to receive only load information.

   URL = service:tn3270://9.37.51.254:23
   Attribute filter = LOAD

   The attribute LOAD would be returned along with its value.  The
   application could then issue other SL_GetAttrs calls to each URL.

   The application would then select the least loaded server as a
   connection target.  If it tries to connect to a server and that
   connection fails, it could then try to connect to the next
   least-loaded server.

5. TN3270E Client Configuration

5.1 SLP Scope

   Scope is a parameter used to control and manage access by clients to
   servers in a network. It is the same as the Service Location
   Protocol scope defined in RFC 2165 [1]. The control scope provides
   is necessary for two reasons:

   As your network, the number of clients, and the number of servers
   grow, it becomes necessary to partition access to those servers by
   the growing number of clients in order to reduce overall traffic on
   the network. It allows administrators to organize users and servers
   in to
<< "into" not "in to"
          administrative groups.

   The meaning of the values of scope is defined by the administrator
   of the network. These values can represent any entity. Commonly,
   they fall along either departmental, geographical, or organizational
   lines.

   Each TN3270E server can be assigned to a scope or scopes. TN3270E
   clients using these servers can be configured for a single specific
   scope or be unscoped.  Different scopes can be assigned for
   different services provided on the server if desired.

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   SLP Service Agents and Directory Agents need to reside in the
   network that support the TN3270E server with configured scopes. If
   you plan to allow clients to locate TN3270E server services based on
   scopes, keep in mind how scope relates to the network as a whole. If
   there are unscoped services in a network where scopes are also used,
   then these services are eligible to satisfy any scoped requests,
   which can potentially put a burden on those service agents and
   directory agents that support the unscoped services. For this
   reason, we recommend that every reachable server either have a
   scope, or no server has a scope defined. If directory agents are to
   be used in the site network (for upward scaling), then they should
   be configured to handle the same scopes as is set for the TN3270E
   servers. In addition, if unscoped services are to be used in
   networks with directory agents, at least one unscoped directory
   agent should be set up.

   Discovery - the scope value can be discovered using the SL_GetAttrs
   API by issuing an unscoped attribute request for a service type with
   an attribute filter of "SCOPE". This API returns a list of scopes
   for services currently active in the network. The list can be
   displayed for user selection.

   For more information on SLP scope refer to Service Location Protocol
   Internet draft [4].
<< Do you want to refer to the new draft [4] or the original [1]?

5.2 DA-Discovery time-out

   The DA Discovery time-out value, a parameter on the SLP_Open API, is
   used to control how long the SLP API must wait to discover Directory
   Agents (DAs) in the network. The discovery request is a multicast,
   and the amount of time required to gather all DA responses might
   vary depending on many factors. If there are no DAs in the network,
   this time-out value can be set to zero to indicate that no DA
   discovery is to be done. The time-out is expressed in milliseconds.

5.3 SA Multicast time-out

   The SA Multicast time-out value.
<< ","
                                    a parameter on the SL_Open API, is
   used to control how long the SLP API must wait to discover services,
   attributes, or service types in a network without at least one DA
   that supports the scope of the request. In this situation, these
   requests are multicast and the SLP API
<< the User Agent waits, not really the SLP API
                                          waits the time-out value to
   gather the multiple responses that are returned. The time-out is
   expressed in milliseconds.

6. Service Registration and Service Templates

   The Service Location Protocol uses the ''service:'' URL scheme name

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   to define URLs called ''service: URLs''. These schemes provide a
   way for clients to obtain configuration information that is needed
   to establish a 3270 session through the Telnet server.  The Service
   Location Protocol provides for service: URLs to be registered and
   discovered.

   Service Registration
   These service registrations contain a service: URL, and possible
   attributes associated with that service.  The service registration
   templates are shown in section 9 below for the communications server
<< Is it appropriate to have Comm Server stuff in this document?
   and the TN3270E server.

   Service Templates
   Service templates are documents defining in a formal way the
   attributes associated with that service that a client may want to
   use. For more information on service templates please refer to,
   Service Templates and service:  Schemes. [3]. The service templates
   are shown in section 9 for the communications server service and the
   TN3270E service.

7. TN3270E Client Implementation Information

7.1 Overview

   A TN3270E client that implements TN3270E SLP load balancing does not
   need to configure an IP Host Address for the TN3270E server it
   desires to connect to. Instead, the IP Host Address of the least
   loaded TN3270E server is discovered by using the SLP load balancing
   described in this document.

   The discovery of the least loaded TN3270E server is done entirely
   outside of and before the TN3270E telnet negotiation. Once the IP
   Host address of the least loaded TN3270E server is discovered, the
   TN3270E client can then start normal TN3270E telnet negotiation.

   The TN3270E client should allow for configuration of the
   following parameters:

   Enable SLP Load Balancing

   This configuration parameter indicates whether or not SLP load
   balancing is enabled. If it is enabled the following three
   configuration parameters must also be configured. If this
   parameter is disabled, SLP load balancing is not supported an
d
<< "and", this typo may be my fault.
   normal TN3270E telnet negotiation is performed.

   Scope Name
   The scope name is a text string that specifies a group of TN3270E

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   servers. The scope name can be used to identify groups of TN3270E
   servers in a departmental or geographic setting. For example, if the
   scope name is Building-D, then the SLP load balancing would search
   all TN3270E servers in the Building-D scope to find the least loaded
   TN3270E server.

   If the scope name is blank, then the scope name is not used. This is
   referred to as unscoped. All TN3270E servers, with or without scope
   names, can be used to satisfy the request for least loaded TN3270E
   servers. Because of the amount of network overhead that this
   involves, this is not recommended.
<< Are you trying to get back to the point of "all unscoped or all scoped"
<< again.  I'm not sure that's clear.  Perhaps you should say what IS
<< recommended.  For example, "In order to cut down on network overhead, it is
<< recommended that either all servers be scoped or no servers be scoped." Then
<< perhaps refer the reader back to section 5.1.

   DA Discovery Time Out Value

   This value is specified in milliseconds and is fully described
   in section 5.2 of this document.

   SA Multicast Time Out Value

   This value is specified in milliseconds and is fully described
   in section 5.3 of this document.

7.2 How to obtain the list of TN3270E servers supporting SLP

   A TN3270E client that implements SLP load balancing uses API calls
   to obtain the list of TN3270E servers supporting SLP load balancing.
   These API calls are described in "An API for Service Location"  [2].
   The following API calls are a subset of  those described in "An API
   for Service Location" [2] and can be used  with  TN3270E SLP session
   balancing.

   SL_Open
   SL_GetService
   SL_GetAttrs
   SL_FreeResult
   SL_Close

7.3 TN3270E Sample Client Flow

7.3.1 Open the SLP connection

   The TN3270E client must first open the SLP library
<< Is this more accurately "open a connection with the SLP User Agent"
<<           or            "open a handle     with the SLP User Agent"
                                                     using the SL_Open
   API call. The SA multicast time out and DA discovery time out values
   are passed as parameters to the SL_OPEN API call.

7.3.2 Query the list of TN3270E servers

   The TN3270E client then queries for the list of TN3270E servers

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   supporting SLP. This is done by using the SL_GetService API call.

   The request string contains information that determines which type
   of TN3270E servers that this client desires to connect to. The
   request string can contain the scope name, pool name, session type
   and 3270 screen size.

   The string has the following format:

   TN3270/<scope name>/LUPOOL == <pool name><TAB><device type>

   The <scope name> is the name of the scope that is configured
   for the TN3270E client. If the scope is blank or null (unscoped
   request), then the scope is not inserted into the request string.

   The <pool name> is a 1 to 8 character upper case string that
   indicates the name of the pool that
<< "to which" not "that"
                                       the TN3270E client desires
   to connect to.
<< remove last "to"  (You seemed to have caught prior possible
<< dangling participles, so I pointed out this one.  Otherwise if
<< you prefer to leave it this way, it's OK by me.)
                   For SLP load balancing, the same pool name must
   be configured on different TN3270E servers.

   The <TAB> is the '/t' tab character which is hexadecimal 0x09.

   The <device type> can be any of the following:

    3270DSC for TN3270E device type IBM-3287-1
    3270002 for TN3270E device types IBM-3278-2 and IBM-3278-2-E
    3270003 for TN3270E device types IBM-3278-3 and IBM-3278-3-E
    3270004 for TN3270E device types IBM-3278-4 and IBM-3278-4-E
    3270005 for TN3270E device types IBM-3278-5 and IBM-3278-5-E
* for TN3270E device type IBM-DYNAMIC
<< What is the dot?  An asterisk perhaps?
<< What about the 3278SCS we saw being sent from CS-NT

   Example:

   For a TN3270E client searching for TN3270E servers in the
   ENGINEERING scope for a model 2 screen size and LUPOOL name pool2,
   the following request string would be constructed:

   "TN3270/ENGINEERING/LUPOOL == pool2<TAB>3270002"
<< You had said that the pool name had to be uppercase letters.  Are
<< you demonstrating the case-insensitive features of SLP or should this
<< example really have POOL2?

   Note: The " characters before and after the string are not
   part of the request string.

7.3.3 Determine loading of each TN3270E server

   Once the list of TN3270E servers and their respective IP Host
   addresses is constructed, each of the TN3270E servers must be
   interrogated to find the loading of each TN3270E server. Then the
   TN3270E client can determine which TN3270E server is least loaded,

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   and use that IP Host address to connect to.
<< remove last "to"

   The TN3270E client uses these load values to determine which TN3270E
   server is least loaded. The TN3270E client then uses the TN3270E
   server's IP Host address to start normal Telnet TN3270E negotiation.

7.4 Recommendations

   It is recommended that the TN3270E client display the IP host
   address that is being used for the TN3270E connection. This gives
   the user knowledge of which TN3270E server the session is connected
   to. For example, the IP host address could be displayed in the
   Windows status bar.

   It is also recommended that the TN3270E client display the resource
   name that is returned by the TN3270E server after connection and
   TN3270E negotiation is completed. This gives the user knowledge of
   which LU resource name in the LUPOOL the session is connected to.
   For example, the resource name could be displayed in the Windows
   status bar, or even in the 3270 OIA line.

   In the event that after the TN3270E client has determined the least
   loaded server and the connection to that server fails for some
   reason, the connection should be closed and an attempt made to
   connect to other TN3270E servers in the list of least loaded
   servers.

   For example, a TN3270E server may reject a connection to a specific
   pool if the pool is full, or if the device type does not match what
   is available in the pool. If this occurs, then an attempt to other
   least loaded TN3270E servers should be performed.

8. Sample Trace Flow of SLP and Session Balancing

   This sample trace flow is provided for informational purposes only.

   SLP: SL_GetService Request: TN3270//LUPOOL == POOL2 3270002/

   SLP: service:tn3270://206.109.45.139:1366, LOAD = 8

   SLP: service:tn3270://206.109.45.140:1366, LOAD = 26
<< How about:
<< SLP: SL_GetService Reply: service:tn3270://206.109.45.139:1366, LOAD = 8
<< SLP: SL_GetService Reply: service:tn3270://206.109.45.140:1366, LOAD = 26

   Connecting to 206.109.45.139...

   TerminalType=NVT

   Connection established

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   Recv <- DO TN3270E

   Send -> WILL TN3270E

   TerminalType=TN3270E

   Recv <- SEND DEVICE_TYPE

   Send -> DEVICE_TYPE REQUEST IBM-3278-2-E CONNECT POOL2

   Recv <- DEVICE_TYPE IS IBM-3278-2-E CONNECT TN8003

   Send -> FUNCTIONS REQUEST BIND_IMAGE SYSREQ

   Recv <- FUNCTIONS IS BIND_IMAGE SYSREQ

9.  Service Registration Messages and Service Templates

   See TN3270E Service Location and Session Balancing Templates
   Internet Draft for submitted templates to IANA for registration. [5]

   Communications Server Service Template
<< Again, is it proper to include Comm Server info in this document?
   URL:service:commserver://<addr-spec>:<port-number>

   The communications server service type is registered whenever the
   communications software is loaded on the server. It describes
   generic attributes of the communications server.  These attributes
   are also repeated on the other service types provided.

   Release = <version/release>

   This is the version and release level of the commserver advertising
   services. Its format is vv.rr.mm where "vv" is the major version
   number, "rr" is the minor version number, and "mm" is the
   modification level. All numbers are padded on the left with zeroes
   to two characters.
   Example: version 3, release 0, mod level 0 is "03.00.00"

   Platform = <platform>

   This is the network operating system platform underlying the
   advertising service. The defined values are:

   IW          Server uses the IntranetWare network operating system

   NT          Server uses the Microsoft NT operating system

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   OS2         Server uses the OS2 operating system

   AIX         Server uses the AIX operating system

   Protocol = <protocol>

   This is the protocol(s) supported by the server providing this
   service. The defined values are:

   IP          Server supports client connections over IP (TCP/IP or
   UDP/IP)

   IPX         Server supports client connections over IPX (SPX/IPX)

   Server name = <server name>

   This is the name of the server that was configured during
   installation. This value has meaning only for the IW platform.

   Communications Server Service Registration Message

   URL:service:commserver://<addr-spec>:<port-number>

   Attributes:

   [(SCOPE=<string>),]

   (RELEASE=03.00.00),

   (PLATFORM=IW),

   (PROTOCOL=IP),

   (SERVERNAME=<string>)

   TN3270 Service Template

   URL: service:tn3270://<addr-spec>:<port-number>

   The tn3270 service provides 3270 gateway access to an SNA network
   via the TN3270 protocol. The attributes reflect the types of 3270
   devices, LU Pools, and load information available on the server.

   Load = <server_load>:
<< What is the meaning of the colon?

   This is the load balancing quantity to use in determining the least
   loaded comm server
<< TN3270E server
                      to attach to for the service. The range of valid
   values is an integral 0 to 100 with 0 indicating the lowest

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   possible load and 100 the highest.

   LU Pool = <pool_name>,

   <pool_name>/t<dev-type> ,

   <pool_name>/t<dev_type>, ...

   <pool_name>/t<dev-type>

   Identifies the LU pool names of LU pools available for use on this
   service with the associated device types supported in each pool.
   Each value is a record where the first token is the pool name of the
   pool and the second token is a device type supported in that pool.
   A pool name without a device type indicates that LUs of unknown type
   are included in the pool. Records associated with a given pool name
   are repeated for each supported device type. A given pool is
   included in a registration request if any PU profile that
   contributes at least one LU to the pool is active on the server. The
   range of valid dev_types are:

   dev_type    Meaning

   3270002     Lu Type 2 Model 2

   3270003     Lu Type 2 Model 3

   3270004     Lu Type 2 Model 4

   3270005     Lu Type 2 Model 5

   3270DSC     Printer LU
<< What about the 3278SCS we saw being sent from CS-NT

   BIND, DATA, RESPONSES, SCS, SYSREQ

   These keyword attributes describe the TN3270e functions supported by
   this service.

   BIND        The server supports the SNA bind image function

   DATA        The non-SNA 3270 data stream is supported by server

   RESPONSES   The server supports SNA response mode

   SCS         The server supports SNA 3270 SCS data stream

   SYSREQ      The SYSREQ keyboard key is supported on server

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   They are present in the service advertisement if the functions they
   describe are available.

   Security = <security>

   This field will contain the security technique supported by the
   server. The actual values are currently being defined in the
   Internet standards body.
<< Current value is NONE

   RFC1576, RFC1646, RFC1647

   The RFC numbers that document features supported by the service.
   Current RFC's for TN3270 include 1576, 1646, and 1647.
<< Do you want to discuss Servername, Release, Protocol, Platform and
<< Scope?

   TN3270 Service Registration Message

   URL: service:tn3270://<addr-spec>:<port-number>
   Attributes:

   [(SCOPE=<string>),]

   (RELEASE=03.00.00),

   (PLATFORM=IW),

   (PROTOCOL=IP),

   (SERVERNAME=<string>),

   (LOAD=<integer 0 to 100>),

   [(LUPOOL=pool-name0/tANY,

   pool-name1/tdevice_type1,

   pool-name2/tdevice-type2, ...

   pool-namen/tdevice-typen)]

   BIND,

   DATA,

   RESPONSES,

   SCS,

   SYSREQ,

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   (SECURITY=NONE),

   RFC1576,

   RFC1646,

   RFC1647,

10. References

   Request For Comments (RFC) and Internet Draft documents are
   available from <URL:ftp://ftp.internic.net> and numerous mirror
   sites.
<< Choose your drafts carefully, new ones don't have the same functionality.
   [1]  J. Veizades, E. Guttman, C. Perkins, and S. Kaplan. Service
        Location Protocol. RFC 2165, July 1997.

   [2]  J. Kempf, E. Guttman, Don Provan. An API for Service Location.
        (work in progress), March 1998.

   [3]  E. Guttman, C. Perkins, J. Kempf. Service Templates and
        service:  Schemes. draft-ietf-svrloc-service-scheme-07.txt
        February 98 (work in progress)

   [4]  E. Guttman, C. Perkins, J. Veizades, Michael Day.
        Service Location Protocol,
        draft-ietf-svrloc-protocol-v2-01.txt October 1997
        (work in progress)

   [5]  J. Naugle, K. Kasthurirangan. TN3270E Service Location and
        Session Balancing Templates.  May 1997 Individual Contribution

 11. Authors' addresses

   Jim Naugle
   IBM
   P.O. Box 12195
   Research Triangle Park, N.C. 27709-2195
   USA
   Phone:  (919) 254-8789
   EMail:  [email-masked]

   Kathuri Kasthurirangan
   IBM
   P.O. Box 12195
   Research Triangle Park, N.C. 27709-2195
   USA
   Phone: (919) 254-5721

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   Gregg Ledford
   Zephyr Development Corporation
   8 Greenway Plaza Suite 1400
   Houston, Texas 77046
   USA

   Phone: (713) 623-0089
   Email:  [email-masked]

Naugle, Kasthurirangan, Ledford      Expires  November 1998  [Page 17]

---

From: Anne Child <[email-masked]>
Date: Tue, 26 May 98 09:30:39 -0500

All-

        Africa: ftp.is.co.za

        Europe: ftp.nordu.net
                ftp.nis.garr.it

Status of This Memo

Copyright Notice

Abstract

1. Table of Contents

Status of This Memo
Abstract
 1. Table of Contents
 2. Introduction
 3. Overview of RFC 2165
     3.1 SLP Agents
     3.2 SLP Relationships
<<   3.2 Service Agents
     3.3 User Agents
     3.4 SLP Relationships

2. Introduction

3.1 SLP Agents

3.2 Service Agents

3.3 User Agents

3.4 SLP Relationships

4.1 TN3270E Server Load

5.1 SLP Scope

   Service Registration

   Service Templates

7.1 Overview

   Scope Name

   SL_Open
   SL_GetService
   SL_GetAttrs
   SL_FreeResult
   SL_Close

   Example:

7.4 Recommendations

   TerminalType=NVT

   Connection established

   Recv <- DO TN3270E

   Send -> WILL TN3270E

   TerminalType=TN3270E

   Recv <- SEND DEVICE_TYPE

   Platform = <platform>

   Protocol = <protocol>

   Attributes:

   [(SCOPE=<string>),]

   (RELEASE=03.00.00),

   (PLATFORM=IW),

   (PROTOCOL=IP),

   (SERVERNAME=<string>)

   TN3270 Service Template

   Load = <server_load>:

   LU Pool = <pool_name>,

   <pool_name>/t<dev-type>

   dev_type    Meaning

   3270DSC     Printer LU

   Security = <security>

   [(SCOPE=<string>),]

   (RELEASE=03.00.00),

   (PLATFORM=IW),

   (PROTOCOL=IP),

   (SERVERNAME=<string>),

   BIND,

   DATA,

   RESPONSES,

   SCS,

   SYSREQ,

   (SECURITY=NONE),

   RFC1576,

   RFC1646,

   RFC1647,

10. References

 11. Authors' addresses

   Jim Naugle
   IBM
   P.O. Box 12195

   Kathuri Kasthurirangan
   IBM
   P.O. Box 12195

   Gregg Ledford

   Phone: (713) 623-0089