RFC 3049 (rfc3049) - Page 2 of 21

TN3270E Service Location and Session Balancing

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
   connections to least loaded servers.

   SNA Gateway - A Systems Network Architecture (SNA) gateway allows
   multiple LAN-attached workstations to access SNA hosts through one or
   more physical connections to one or more hosts.  A SNA gateway acts
   as a protocol converter between workstations attached to a LAN and a



Naugle, et al.              Standards Track