TN3270E Service Location and Session Balancing
RFC 3049

Document Type RFC - Proposed Standard (January 2001; No errata)
Last updated 2013-03-02
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Network Working Group                                          J. Naugle
Request for Comments: 3049                             K. Kasthurirangan
Category: Standards Track                                            IBM
                                                              G. Ledford
                                                      Zephyr Development
                                                            January 2001

             TN3270E Service Location and Session Balancing

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

Abstract

   This document discusses the implementation of Service Location
   Protocol (SLP) 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 SLP
   support.

Table of Contents

   1. Introduction and Terminology .................................  2
      1.1 Terminology ..............................................  2
   2. An Overview of RFC 2165 ......................................  3
      2.1 SLP Agents ...............................................  3
      2.2 Service Agents ...........................................  3
      2.3 User Agents ..............................................  4
   3. TN3270E Server Environment and Load ..........................  4
      3.1 TnN3270E Server Load .....................................  4
   4. TN3270E Client Configuration .................................  6
      4.1 SLP Scope ................................................  6
      4.2 DA-Discovery Time-Out ....................................  6
      4.3 SA-Discovery Time-Out ....................................  7
   5. TN3270E Client Implementation Information ....................  7
      5.1 Overview .................................................  7

Naugle, et al.              Standards Track                     [Page 1]
RFC 3049              TN3270E Location & Balancing          January 2001

      5.2 How to Obtain List of TN3270E Servers Supporting SLP .....  8
      5.3 TN3270E Sample Client Flow ...............................  9
         5.3.1 Open the SLP connection .............................  9
         5.3.2 Query the list of TN3270E servers ...................  9
         5.3.3 Forward Looking Example using SLPv2 ................. 10
         5.3.4 Determine loading of each TN3270E server ............ 10
      5.4 Recommendations .......................................... 11
   6. Sample Trace Flow of SLP and Session Balancing ............... 11
   7. Service Templates and Service Registration ................... 12
      7.1 The TN3270E Service Type Template ........................ 12
      7.2 The Server Service Template .............................. 16
      7.3 Template Contact Information ............................. 17
      7.4 Security Considerations .................................. 17
      7.5 Sample TN3270 Service Registration Message ............... 18
      7.6 Sample Server Service Registration Message ............... 19
   8. References ................................................... 19
   9. Authors' Addresses ........................................... 20
   10. Full Copyright Statement .................................... 21

1. Introduction and Terminology

   This document will provide information on Service Location Protocol
   implementation to discover TN3270E servers in a network and session
   balance among those servers.  This implementation follows the
   standards track RFC 2165, Service Location Protocol [1] but also
   provides some examples when using Service Location Protocol version 2
   to be forward looking.  Service Location Protocol version 2 is
   documented in RFC 2608 [4] and RFC 2609 [2].

1.1 Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119  [1].

   Session Balance - This refers to the ability of TN3270E client to use
   server load information to establish a TN3270E connection to the
   TN3270E server with the least load at that time.  The purpose is to
   distribute the connection of TN3270E sessions among more than one
   TN3270E server, and one server will not be excessively loaded.  The
   term "load balance" is a more general term, with respect to server
   load, and in this document we are focusing on the TN3270E session
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