Front cover IBM z/OS V2R2 Communications Server TCP/IP Implementation: Volume 3 High Availability, Scalability, and Performance Bill White Octavio Ferreira Teresa Missawa Teddy Sudewo Redbooks International Technical Support Organization IBM z/OS V2R2 Communications Server TCP/IP Implementation: Volume 3 High Availability, Scalability, and Performance August 2016 SG24-8362-00 Note: Before using this information and the product it supports, read the information in “Notices” on page vii. First Edition (August 2016) This edition applies to Version 2, Release 2 of z/OS Communications Server. © Copyright International Business Machines Corporation 2016. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . vii Trademarks . viii IBM Redbooks promotions . ix Preface . xi Authors. xii Now you can become a published author, too! . xiii Comments welcome. xiii Stay connected to IBM Redbooks . xiv Chapter 1. An introduction to IBM z/OS Communications Server high availability technologies . 1 1.1 Overview of high availability . 2 1.2 Fundamental technologies for z/OS TCP/IP availability . 2 1.2.1 Single z/OS system availability . 2 1.2.2 z/OS Parallel Sysplex availability . 3 1.2.3 Virtual IP addressing. 4 1.2.4 z/OS network connectivity and dynamic routing . 5 1.2.5 Single-instance and multiple-instance applications. 7 1.2.6 Balancing workload across multiple application instances . 8 1.3 Quick-start table . 11 Chapter 2. Virtual IP addressing . 13 2.1 Basic concepts of virtual IP addressing . 14 2.1.1 Static VIPA . 14 2.1.2 Dynamic VIPA. 14 2.2 Importance of VIPA . 16 2.3 Types of DVIPA. 17 2.3.1 Stack-managed DVIPA . 17 2.3.2 Event-activated DVIPA . 17 2.3.3 Distributed DVIPA (sysplex distributor). 19 2.3.4 Single-stack DVIPA upper limit . 26 2.3.5 Making use of DVIPAs . 26 2.4 Static VIPA example . 27 2.5 Dynamic VIPA (DVIPA) example . 31 2.5.1 Stack-managed DVIPA . 31 2.5.2 Event-activated DVIPA example. 41 2.5.3 Distributed DVIPA (sysplex distributor) example . 41 2.6 Sysplex problem detection and recovery . 41 2.6.1 Problem detection . 41 2.6.2 Automatic control of leaving/joining the sysplex group . 41 2.6.3 Automatic control of the DVIPA activation timing . 42 2.6.4 Monitoring the network reachability. 45 2.7 Controlling DVIPA with commands . 53 2.7.1 LEAVEGROUP and JOINGROUP . 54 2.7.2 DEACTIVATE and REACTIVATE. 56 2.7.3 QUIESCE and RESUME. 58 © Copyright IBM Corp. 2016. All rights reserved. iii Chapter 3. VIPA without dynamic routing . 63 3.1 Basic concepts . 64 3.2 High availability using ARP takeover in one TCP/IP stack . 65 3.2.1 Implementation . 65 3.2.2 Verification . 67 3.3 High availability across multiple TCP/IP stacks using DVIPA . 71 3.3.1 Implementation . 72 3.3.2 Verification . 75 3.4 Debugging tips . 86 Chapter 4. VIPA with dynamic routing. 87 4.1 Basic concepts of high availability using dynamic routing. 88 4.1.1 Dynamic routing and OMPROUTE . 88 4.1.2 Advertisement of VIPA addresses . 88 4.1.3 Multiple links between IP nodes and LPARs. 92 4.2 Design example of DVIPA with dynamic routing. 97 4.2.1 Overview . 97 4.2.2 Implementation tasks . 98 4.2.3 Verifying that the configuration works as planned. 104 4.3 High availability scenarios. 107 4.3.1 Adapter interface failure . 107 4.3.2 Application movement using VIPADEFINE. 111 4.3.3 Stack failure scenario using VIPADEFINE and VIPABACKUP. 115 4.3.4 IPv6 stack failure scenario with VIPADEFINE and VIPABACKUP . 118 4.4 Sysplex-Wide Security Associations . 121 4.4.1 Enabling the SWSA in a stack with IPSec defined . 122 4.4.2 Verifying the SWSA . 125 4.4.3 Sysplex-Wide Security Associations for IPv6 . 127 Chapter 5. Internal application workload balancing . 129 5.1 Basic concepts of internal application workload balancing . 130 5.2 Sysplex distributor. 131 5.2.1 Sysplex distributor: Principles of operation . 131 5.2.2 Sysplex distributor and quality of service policy . 132 5.2.3 Monitoring the responsiveness of the target server . 133 5.2.4 Workload distribution methods . ..