Front cover Introduction to the New Mainframe: Networking Concepts of mainframe-based data communications Methods for implementing TCP/IP and SNA on z/OS Basic skills in network operations, security, and problem determination Christopher Hastings Matt Nuttall Micky Reichenberg ibm.com/redbooks International Technical Support Organization Introduction to the New Mainframe: Networking August 2006 SG24-6772-00 Note: Before using this information and the product it supports, read the information in “Notices” on page 329. First Edition (August 2006) This edition applies to Version 1, Release 7, Modification 0 of z/OS (5694-A01). © Copyright International Business Machines Corporation 2006. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. iii iv Introduction to the New Mainframe: Networking Contents Preface . xiii How this text is organized . xiv How each chapter is organized . xv The team that wrote this redbook. xvi Comments welcome. xvii Part 1. Introduction to networking on the mainframe . 1 Chapter 1. Mainframes and networks . 3 1.1 Mainframes, networks, and you . 4 1.2 Networks and online systems . 5 1.3 Why are networks important? . 7 1.4 Examples of mainframe-based networks . 7 1.4.1 ATM cash withdrawal . 8 1.4.2 Credit purchase at a retail store . 9 1.4.3 Technology choices abound in network technology . 9 1.5 Who supports the network?. 10 1.6 What are the basic elements of a network? . 11 1.7 Overview of mainframe network capabilities . 12 1.7.1 z/OS Communications Server. 15 1.7.2 SNA and TCP/IP on z/OS . 17 1.8 Security in a network . 17 1.8.1 Data protection . 18 1.8.2 Availability . 19 1.9 Summary . 19 Chapter 2. Network layers and protocols review . 21 2.1 Coming to terms . 22 2.1.1 Layers . 22 2.2 Physical media, layer 1 . 23 2.2.1 Network interface card (NIC). 24 2.3 Data link layer, layer 2. 25 2.3.1 Ethernet. 25 2.3.2 Media access control (MAC) addressing . 27 2.4 Network layer, layer 3 . 27 2.4.1 Address Resolution Protocol (ARP) . 29 2.4.2 Network types . 29 2.4.3 Local area network (LAN) . 29 2.4.4 Wide area network (WAN) . 30 © Copyright IBM Corp. 2006. All rights reserved. v 2.4.5 Virtual LAN . 30 2.4.6 Network routing . 31 2.4.7 Building routing tables. 34 2.4.8 Internet Control Message Protocol (ICMP) . 36 2.4.9 Other layer 3 protocols . 37 2.5 Transport layer, layer 4 . 37 2.5.1 Transmission Control Protocol (TCP) . 37 2.5.2 User Datagram Protocol (UDP). 40 2.5.3 Sockets . 40 2.6 Applications . 41 2.7 Security . 41 2.7.1 Firewalls and gateways. 41 2.7.2 Security protocols . 42 2.7.3 Protection . 42 2.8 Systems Network Architecture (SNA) . 42 2.9 Summary . 43 Chapter 3. Hardware connectivity on the mainframe. 45 3.1 Connecting the mainframe . 46 3.2 Channel subsystem (CSS) . 46 3.2.1 Control units . 48 3.2.2 Logical channel subsystem (LCSS) . 48 3.3 The mainframe channel subsystem and network links . 49 3.4 Hardware channels . 51 3.5 Channel command word (CCW) . 52 3.5.1 CCW-based operations. 52 3.5.2 Parallel channel. 52 3.5.3 Enterprise System Connectivity (ESCON) channel . 53 3.5.4 Fiber connection (FICON) . 55 3.5.5 Channel-attached network devices . 55 3.6 Coupling channels. 55 3.7 Open Systems Adapter (OSA) . 56 3.7.1 Queued Direct I/O (QDIO). 58 3.7.2 Non-QDIO mode . 61 3.7.3 OSC mode . 61 3.7.4 Open Systems Adapter for NCP (OSN) . 61 3.8 HiperSockets . 63 3.9 Making the connections. 65 3.10 Summary . 67 Chapter 4. Sample configuration . 69 4.1 Requirements for a mainframe network . 70 4.2 The ZOS Company data center . 70 vi Introduction to the New Mainframe: Networking 4.2.1 Key mainframe network availability aspects . 73 4.3 Summary . 77 Part 2. TCP/IP implementation on the mainframe . 79 Chapter 5. TCP/IP on z/OS. 81 5.1 The heart of the matter . 82 5.1.1 Control issues and the stack . 82 5.1.2 IPv4 versus IPv6 . 83 5.2 The TCP/IP profile. 83 5.2.1 Profile statements . ..