z/OS Communications Server 2.4 IPv6 Network and Application Design Guide IBM SC27-3663-40 Note: Before using this information and the product it supports, be sure to read the general information under “Notices” on page 147. This edition applies to Version 2 Release 4 of z/OS® (5650-ZOS), and to subsequent releases and modifications until otherwise indicated in new editions. Last updated: 2021-06-22 © Copyright International Business Machines Corporation 2002, 2020. US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Figures................................................................................................................ vii Tables.................................................................................................................. ix About this document.............................................................................................xi Who should read this document................................................................................................................. xi How this document is organized.................................................................................................................xi How to use this document.......................................................................................................................... xi How to contact IBM service...................................................................................................................xi Conventions and terminology that are used in this information............................................................... xii Prerequisite and related information........................................................................................................xiii Summary of changes for IPv6 Network and Application Design Guide..................xvii Changes made in z/OS Communications Server Version 2 Release 4.................................................... xvii Changes made in z/OS Communications Server Version 2 Release 3.................................................... xvii Changes made in z/OS Version 2 Release 2.............................................................................................xvii Chapter 1. Internet Protocol Version 6................................................................... 1 Neighbor discovery...................................................................................................................................... 2 Comparison of IPv6 and IPv4 characteristics.............................................................................................3 Chapter 2. IPv6 addressing....................................................................................5 Textual representation of IPv6 addresses.................................................................................................. 5 Textual representation of IPv6 prefixes...................................................................................................... 6 IPv6 address space......................................................................................................................................6 IPv6 addressing model................................................................................................................................ 7 Scope zones................................................................................................................................................. 7 Categories of IPv6 addresses......................................................................................................................8 Unicast IPv6 addresses..........................................................................................................................8 Multicast IPv6 addresses.....................................................................................................................11 Anycast IPv6 addresses.......................................................................................................................13 Typical IPv6 addresses assigned to a node.............................................................................................. 13 IPv6 address states................................................................................................................................... 13 Chapter 3. IPv6 protocol...................................................................................... 15 Extension headers..................................................................................................................................... 15 Fragmentation in an IPv6 network............................................................................................................15 Fragmentation and UDP/RAW..............................................................................................................16 Path MTU discovery................................................................................................................................... 16 IPv6 routing................................................................................................................................................16 Router discovery...................................................................................................................................16 ICMPv6 redirects..................................................................................................................................17 Dynamic routing protocols................................................................................................................... 17 Considerations for route selection.......................................................................................................19 Considerations for multipath routes....................................................................................................19 The VARY TCPIP,,OBEYFILE command and routes............................................................................. 20 Policy-based routing..................................................................................................................................20 ICMPv6.......................................................................................................................................................20 Multicast Listener Discovery......................................................................................................................21 iii Neighbor discovery.................................................................................................................................... 22 Router advertisements.........................................................................................................................22 Redirect processing..............................................................................................................................26 Duplicate address detection................................................................................................................ 26 Address resolution............................................................................................................................... 27 Neighbor unreachability detection...................................................................................................... 28 Assigning IP addresses to interfaces........................................................................................................ 28 Stateless address autoconfiguration................................................................................................... 28 IP address takeover following an interface failure .............................................................................29 How to get addresses for VIPAs...........................................................................................................30 IPv6 temporary addresses with random interface IDs............................................................................ 30 Configuring a TCP/IP stack to generate IPv6 temporary addresses.................................................. 30 Enabling a client application to use IPv6 temporary or public addresses......................................... 31 Displaying the configured and generated temporary or public address information.........................32 Default address selection..........................................................................................................................33 Policy table for IPv6 default address selection...................................................................................33 Default destination address selection................................................................................................. 34 Default source address selection........................................................................................................ 35 Configuring the policy table for default address selection................................................................. 37 Displaying the policy table for default address selection................................................................... 38 Enabling IPv6 communication between IPv6 nodes or networks in an IPv4 environment.................... 38 Enabling end-to-end communication between IPv4 and IPv6 applications........................................... 39 IPv6 application on a dual-mode stack..............................................................................................