OSA Mainframe

5/20/2018 OSA Mainframe

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ibm.com/redbooks

Front cover

OSA-ExpressImplementation Guide

Bill W

Joerg Ha

Thomas Wie

Product, planning, and quickstart information

Realistic examples and

considerations

Hardware and software

setup definitions
http://www.redbooks.ibm.com/http://www.redbooks.ibm.com/http://www.redbooks.ibm.com/http://www.redbooks.ibm.com/


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International Technical Support Organization

OSA-Express Implementation Guide

April 2009

SG24-5948-05


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Copyright International Business Machines Corporation 1999, 2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009.

All rights reserved.

Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP ScheduleContract with IBM Corp.

Sixth Edition (April 2009)

This edition applies to the OSA-Express3, OSA-Express2, and OSA-Express features installed in the IBMSystem z10 and System z9 severs.

Note: Before using this information and the product it supports, read the information in Notices on

page ix.


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Copyright IBM Corp. 1999, 2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009. All rights reserved. iii

Contents

Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

Trademarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

The team that wrote this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi

Become a published author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xii

Comments welcome. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xii

Chapter 1. OSA overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.1.1 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.1.2 QDIO mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.1.3 Non-QDIO mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.1.4 OSA addressing support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.1.5 OSA/SF support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91.2 OSA capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.2.1 Virtual IP address (VIPA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.2.2 Primary/secondary router function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.2.3 IPv6 support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.2.4 Large send for TCP/IP traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.2.5 VLAN support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.2.6 SNMP support for z/OS and Linux on System z . . . . . . . . . . . . . . . . . . . . . . . . . . 14

1.2.7 TCP/IP multicast and broadcast support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.2.8 ARP cache management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.2.9 IP network availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.2.10 Checksum offload support for z/OS and Linux on System z. . . . . . . . . . . . . . . . 17

1.2.11 Layer 2 support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181.2.12 QDIO data connection isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

1.2.13 Layer 3 VMAC for z/OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

1.2.14 Enterprise Extender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.2.15 TN3270E Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.2.16 OSA for NCP support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Chapter 2. Quick start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252.1 Software support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.2 OSA definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.2.1 Modes of operation and addressing support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.3 OSA/SF requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.4 Quick start tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.4.1 OSA function support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.4.2 Quick start tables for z/OS and z/VM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5 Policy-based networking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Chapter 3. Hardware configuration definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

3.1 Configuration chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

3.2 Hardware Configuration Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

3.2.1 Channel path definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.2.2 Control unit definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2.3 Device definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41


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3.2.4 Generating the input IOCDS from HCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Chapter 4. Setting up and using OSA/SF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474.1 Setup requirements and overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.2 Setting up OSA/SF in the z/OS environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.2.1 Setting up APPC and VTAM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

4.2.2 Setting up OSA/SF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504.2.3 Communicating with OSA/SF using TCP/IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

4.3 Installing OSA/SF GUI on a workstation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

4.3.1 Checking the hardware configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

4.3.2 Checking the software configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

4.3.3 Downloading and installing the Java runtime and JavaHelp files . . . . . . . . . . . . . 52

4.3.4 Downloading the code from z/OS using FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.3.5 Defining the CLASSPATH environment variable . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.3.6 Starting the OSA/SF GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.4 Using the OSA/SF GUI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Chapter 5. QDIO mode for z/OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.1 QDIO environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.2 Hardware Configuration Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 685.3 Missing Interrupt Handler for QDIO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.4 Customizing the z/OS network environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

5.4.1 Defining OSA devices to z/OS Communications Server for QDIO . . . . . . . . . . . . 70

5.4.2 VTAM definitions (TRL major node) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.4.3 TCP/IP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

5.5 Activation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.5.1 Verifying that devices are online . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.5.2 VTAM activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

5.5.3 TCP/IP devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

5.6 Relevant status displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

5.7 SNA support for QDIO mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Chapter 6. QDIO mode for z/VM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

6.1 QDIO environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

6.2 Hardware Configuration Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

6.3 Missing Interrupt Handler for QDIO. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

6.4 Customizing the z/VM network environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.4.1 TCP/IP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

6.5 Activation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

6.5.1 Verifying that devices are online . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

6.5.2 TCP/IP activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

6.6 Relevant status displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Chapter 7. Non-QDIO mode for z/OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

7.1 Configuration information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

7.2 Hardware definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

7.3 Creating and activating the OSA configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

7.3.1 TCP/IP definitions in OSA/SF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

7.3.2 SNA definition in OSA/SF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

7.3.3 Activating the OSA configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

7.3.4 Displaying the MAC address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

7.4 Customizing the z/OS network environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

7.4.1 VTAM definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

7.4.2 TCP/IP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101


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7.5 Activating the connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

7.5.1 Verifying that devices are online . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

7.5.2 VTAM activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

7.5.3 TCP/IP activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

7.6 Relevant status displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

Chapter 8. Non-QDIO mode for z/VM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1078.1 Configuration information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

8.2 Hardware definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

8.3 OSA configuration and OAT definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

8.3.1 Creating and activating our OSA configuration and OAT . . . . . . . . . . . . . . . . . . 109

8.4 Network definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

8.4.1 VTAM definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

8.4.2 TCP/IP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

8.5 Activating the connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

8.5.1 Verifying that devices are online . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

8.5.2 VTAM activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

8.5.3 TCP/IP activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

8.6 Relevant status displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Chapter 9. z/OS VMAC support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1239.1 Virtual MAC overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

9.1.1 Virtual MAC concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

9.1.2 Virtual MAC address assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

9.2 Virtual MAC implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

9.2.1 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Chapter 10. VLAN support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

10.1 VLAN overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

10.1.1 Types of connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

10.1.2 VLAN tagging basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134

10.2 General VLAN design considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13510.2.1 VLAN configuration example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

10.2.2 Sharing an OSA port with the same VLAN ID. . . . . . . . . . . . . . . . . . . . . . . . . . 137

10.2.3 Primary and secondary router support with VLANs . . . . . . . . . . . . . . . . . . . . . 137

10.2.4 Operating system support. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

10.3 VLAN support for z/OS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

10.3.1 VLAN implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

10.3.2 Configuring OSA with VLAN ID. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

10.3.3 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

10.4 VLAN support for Linux . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

10.4.1 VLAN implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

10.4.2 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

10.5 VLAN support in z/VM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14810.5.1 z/VM native VLAN support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

10.5.2 Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

Chapter 11. z/VM virtual switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15111.1 Virtual switch description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

11.1.1 VSWITCH controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

11.1.2 Network interface card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

11.1.3 VSWITCH capabilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

11.2 Our VSWITCH environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

11.3 Configuring a Layer 2 VSWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158


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11.3.1 Defining the virtual switch environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

11.3.2 Authorizing the guest system access to the virtual switch . . . . . . . . . . . . 159

11.3.3 Connecting the guest systems to the VSWITCH . . . . . . . . . . . . . . . . . . . . . 160

11.3.4 Verifying the virtual switch configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

11.3.5 Setting up Layer 2 for the guest systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

11.3.6 Creating definitions for Layer 2 support - SUSE and Red Hat . . . . . . . . . . . . . 163

11.3.7 Making permanent device and network definitions . . . . . . . . . . . . . . . . . . . . . . 16511.4 Configuring VLAN support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

11.4.1 Defining VLAN capabilities to the virtual switch . . . . . . . . . . . . . . . . . . . . . . . . 168

11.4.2 Authorizing Linux guests access to the virtual switch with VLAN IDs. . . . . . . . 169

11.4.3 Adding VLANs to the guest systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

11.4.4 Adding VLAN support to the z/OS TCP/IP stacks. . . . . . . . . . . . . . . . . . . . . . . 173

11.4.5 Configuring trunk mode in the Ethernet switch for the OSA connections . . . . . 173

11.4.6 Verifying the VLAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

11.5 Enabling port isolation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

11.5.1 Port isolation off - systems sharing the same VSWITCH and OSA . . . . . . . . . 178

11.5.2 Port isolation on - systems sharing the same VSWITCH and OSA . . . . . . . . . 179

11.6 Configuring link aggregation support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

11.6.1 Defining link aggregation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18111.6.2 Setting up the external Ethernet switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

11.6.3 Verifying the configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Appendix A. OSA features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

OSA feature descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188

Appendix B. OSA-Express Network Traffic Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . 197OSA-Express Network Traffic Analyzer (OSAENTA). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

Determining the microcode level for OSA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

Defining TRLE definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199

Checking TCPIP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200

Customizing OSA-Express Network Traffic Analyzer (NTA). . . . . . . . . . . . . . . . . . . . . 201

Defining a resource profile in RACF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207Allocating a VSAM linear data set. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Starting the OSAENTA trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Additional tools for diagnosing CS for z/OS IP problems. . . . . . . . . . . . . . . . . . . . . . . . . . 216

Network Management Interface API (NMI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218

Appendix C. HMC and SE tasks for OSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219HMC advanced facilities for OSA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220

Trace functions for OSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222

Hardware functions for OSA-Express . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

View code level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

Configuring OSA channels on/off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Logging on to the Support Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229

CHPID Configure on/off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230

Logging off from the Support Element . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

Appendix D. Useful commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235

z/OS commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236

z/VM commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

Defining and coupling a NIC using CP commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239

Linux on System z TCP/IP commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240


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Appendix E. Using the OSA/SF REXX interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

Creating the OSA configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

Creating the OSA configuration file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

Creating the OAT file . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

Activating the OSA configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244

Appendix F. TCP/IP Passthru mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251Default mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

HCD requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

Displaying the default OAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

Customizing z/OS TCP/IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256

TCP/IP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

Activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

Verifying that devices are online . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

Activating TCP/IP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

Appendix G. Sample definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261Sample environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

z/OS definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262

TCP/IP profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263VTAM definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

z/VM TCP/IP profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

Appendix H. ARP takeover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269ARP takeover description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270

ARP takeover definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

TCP/IP definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

Ethernet switch definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

Verifying ARP takeover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

Pulling the CAT5 cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

Stopping the device in the TCP/IP stack. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275

Appendix I. HiperSockets Accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 277

HiperSockets Accelerator description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278

HiperSockets definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

Verifying HiperSockets Accelerator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280

Appendix J. RMF in an OSA environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283RMF for OSA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

RMF Monitor II output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

The Channel Activity Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

Appendix K. Authorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

z/VM virtual switch authorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

Running with CP authorization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288Running with RACF authorization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

Related publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

IBM Redbooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

Other publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

Online resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

How to get IBM Redbooks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

Help from IBM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295


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Notices

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IBM may not offer the products, services, or features discussed in this document in other countries. Consultyour local IBM representative for information on the products and services currently available in your area. Anyreference to an IBM product, program, or service is not intended to state or imply that only that IBM product,program, or service may be used. Any functionally equivalent product, program, or service that does notinfringe any IBM intellectual property right may be used instead. However, it is the user's responsibility toevaluate and verify the operation of any non-IBM product, program, or service.

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Trademarks

IBM, the IBM logo, and ibm.com are trademarks or registered trademarks of International Business MachinesCorporation in the United States, other countries, or both. These and other IBM trademarked terms aremarked on their first occurrence in this information with the appropriate symbol ( or ), indicating USregistered or common law trademarks owned by IBM at the time this information was published. Such

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The following terms are trademarks of the International Business Machines Corporation in the United States,other countries, or both:

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Preface

This IBM Redbooks publication will help you to install, tailor, and configure the Open

Systems Adapter (OSA) features that are available on IBM System z10 and IBM Systemz9 servers. It focuses on the hardware installation and the software definitions that are

needed to provide connectivity to LAN environments. It provides information to help you withplanning and system setup. It also includes helpful utilities and commands for monitoring and

managing the OSA features.

The target audience for this document is system engineers, network administrators, andsystem programmers who will plan for and install OSA features. The reader is expected tohave a good understanding of System z hardware, HCD or IOCP, OSA/SF, SNA/APPN, and

TCP/IP.

The team that wrote this book

This book was produced by a team of specialists from around the world working at theInternational Technical Support Organization (ITSO), Poughkeepsie Center.

Bill Whiteis a Project Leader and Senior Networking and Connectivity Specialist at the ITSO

in Poughkeepsie, New York.

Joerg Haertelis a Senior IT Specialist working for System z Sales Technical Support inGermany. He holds a diploma in communications engineering. He has 20 years of technical

experience in the z/VM and z/VSE environment. Joerg has worked at IBM for 22 years.His areas of expertise include Linux for System z, TCP/IP, DB2, and System z-relatedhardware. He has written extensively on CICS, CTG, and MQSeries, setup for Linux on

System z, as well as on z/VSE.

Thomas Wienertis a Senior IT Specialist working for IBM STG in Germany, supportingclients in Germany, Austria, Sweden and Switzerland. He has over 24 years of experience

with IBM networking. Thomas has been with IBM for 19 years working as a Systems Engineerin technical sales, product support and implementation services. His areas of expertise

include Communications Server for z/OS, OSA-Express, z/OS, Parallel Sysplex, andSystem z-related hardware. He co-authored a number of IBM Redbooks publications.

Thanks to the following people for their contributions to this project:

Dave Bennin, Roy Costa, and Robert HaimowitzITSO, Poughkeepsie Center

Connie BeuselinckSystem z Product Planning, IBM Poughkeepsie

Joel GoldmanSystem z (OSA firmware) Development, IBM Poughkeepsie

Susan Farrell and Angelo Macchiano

z/VM Networking Development, IBM Endicott

Cliff LakingTechnical Support - z/VM and Linux on System z, IBM UK


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Chapter 1. OSA overview

This chapter describes the Open Systems Adapter-Express3 (OSA-Express3) and Open

Systems Adapter-Express2 (OSA-Express2) features. These features provide connectivity toother servers and clients on 1000BASE-T Ethernet (10, 100, and 1000 Mbps), Gigabit

Ethernet (GbE), and 10 Gigabit Ethernet environments.

The following topics are covered:

Functional description

Operating modes

OSA capabilities

1

Terminology:If not specifically stated otherwise, the term OSA applies to theOSA-Express3 and OSA-Express2 features throughout this book.


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1.1 Functional description

The Open Systems Adapter-Express3 (OSA-Express3), and OSA-Express2 featurescomprise a number of integrated hardware features that can be installed in a System z I/Ocage, becoming integral components of the servers I/O subsystems. They provide high

function, connectivity, bandwidth, data throughput, network availability, reliability, and

recovery.

All OSA-Express3 and OSA-Express2 features are hot-pluggable.

Figure 1-1shows the OSA-Express3 and OSA-Express2 Ethernet features available on theSystem z10 and System z9 servers.

Figure 1-1 OSA-Express3 and OSA-Express2 Ethernet connectivity

For a complete list and description of all the OSA-Express3 and OSA-Express2 features

offered on the System z10 and System z9 servers, go to Appendix A, OSA features onpage 187.

1.1.1 Operating modes

The integration of a channel path with network ports makes the OSA a unique channel orCHPID type, recognized by the hardware I/O configuration as one of the following:

OSD (Queued Direct Input/Output) OSE (non Queued Direct Input/Output) OSC (OSA Integrated Console Controller) OSN (Open System Adapter for NCP)

Note that not all features support all CHPID types.

Ethernet

GbE

z10 BC

1000BA

SE-T

10GbE

z9 EC

GbE

10GbE

1000BASE-T

z9 BC

10GbE

GbE

1000BASE-T

z10 EC

GbE

1000BASE-T

10Gb

E


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Chapter 1. OSA overview 3

Table 1-1gives an overview of the type of traffic supported and whether OSA/SF is required

to configure the OSA-Express3 or OSA-Express2 CHPID, based on the supported modes ofoperation.

Table 1-1 Supported CHPID types

Open Systems Adapter Support Facility (OSA/SF)

OSA/SF is a host-based tool used to customize and manage all OSA features.

OSA/SF is not required for the OSA feature that is configured for the QDIO mode, or thedefault IP Passthru non-QDIO mode. However, it can be used for problem determination

purposes.

OSA/SF is not required for OSA CHPID types OSC and OSN, although information aboutchannel usage can by displayed through OSA/SF for OSN CHPIDs.

OSA/SF is a required facility when the OSA feature is being configured for sharednon-QDIO mode and where SNA definitions are involved.

One OSA/SF application can communicate with all OSA features in a System z server.

OSA/SF communicates with an OSA feature through a device (type OSAD) defined viaHCD/IOCP.

For more details, refer to 1.1.5, OSA/SF support on page 9.

QDIO versus non-QDIOFigure 1-2 on page 4illustrates the much shorter I/O process when in QDIO mode comparedwith non-QDIO mode. I/O interrupts and I/O path-lengths are minimized, resulting in improved

performance versus non-QDIO mode, reduction of System Assist Processor (SAP)utilization, improved response time, and server cycle reduction.

CHPID

type

Feature SNA/APPN/

HPR traffic

TCP/IP

traffic

3270

traffic

OSA/SF

OSD OSA-Express3 10GbE LR

OSA-Express3 10GbE SR

OSA-Express2 10GbE LR

OSA-Express3 GbE

OSA-Express2 GbE

OSA-Express3 1000BASE-T


Noa,b

Noa,b

Noa,b

Noa,b

Noa,b

Noa,b

Noa,b

a. SNA over IP with the use of Enterprise Extender or TN3270 (see Enterprise Extender on

page 21and TN3270E Server on page 21).

b. Layer 2 support allows for non-IP protocols, such as SNA (see Layer 2 support on page 18).

Yes

Yes

Yes

Yes

Yes

Yes

Yes

No

No

No

No

No

No

No

Optional

Optional

Optional

Optional

Optional

Optional

Optional

OSE OSA-Express3 1000BASE-T


Yes

Yes

Yes

Yes

No

No

Required

Required

OSC OSA-Express3 1000BASE-T


No

No

No

No

Yes

Yes

n/a

n/a

OSN OSA-Express3 GbE

OSA-Express2 GbE



Yesc

Yesc

Yesc

Yesc

c. Supports SNA PU Type 5 and PU Type2.1 (see OSA for NCP support on page 22).

No

No

No

No

No

No

No

No

Optional

Optional

Optional

Optional


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Figure 1-2 Non-QDIO data path versus QDIO data paths

Note that OSA-Express3 features use Direct Memory Access (DMA) and a data router modelto eliminate store and forward delays that could occur with the OSA-Express2 features when

in QDIO mode.

Also in QDIO mode, all OSA features receive configuration information from the host

dynamically. This reduces configuration and setup time, eliminates duplicate data entry, andreduces the possibility of data entry errors and incompatible definitions.

We recommend the use of QDIO mode wherever possible.

1.1.2 QDIO mode

QDIO is a highly efficient data transfer mechanism that is designed to dramatically reduce

system overhead and improve throughput by using system memory queues and a signalingprotocol to directly exchange data between the OSA microprocessor and network software.QDIO is the interface between the operating system and the OSA hardware.

The components that make up QDIO are DMA, data router (OSA-Express3 only), Priority

Queuing (z/OS only), dynamic OSA Address Table building, LPAR-to-LPAR communication,and Internet Protocol (IP) Assist functions.

QDIO supports IP and non-IP traffic with the OSA-Express3 and OSA-Express2 features.

These features support two transport modes: Layer 2 (Link Layer) for IP and non-IP traffic,

and Layer 3 (Network Layer) for IP traffic only. A more detailed discussion about the Layer 2support is provided in 1.2.11, Layer 2 support on page 18.

Direct Memory Access (DMA)OSA and the operating system share a common storage area for memory-to-memorycommunication, reducing system overhead and improving performance. Data can move

directly from the OSA microprocessor to system memory and vice versa, utilizing a store andforward technique in DMA. There are no read or write channel programs for data exchange.For write processing, no I/O interrupts have to be handled. For read processing, the number

of I/O interrupts is minimized.

Host

Memory

LAN

NIC

Control

Unit

Channel

Non-QDIO (LCS)

QDIO

Host

Memory

OSA-Express2

LAN

Store and forward

LAN

OSA-Express3

Host

Memory

Data router

QDIO

OSA-Express

Host

Memory

Host

Memory

LAN

NIC

Control

Unit

Channel

Non-QDIO (LCS)

QDIO

Host

Memory

OSA-Express2

LAN

Store and forward

LAN

OSA-Express3

Host

Memory

Data router

QDIOQDIO

Host

Memory

Host

Memory

OSA-Express2

LAN

Store and forward

LAN

OSA-Express3

Host

Memory

Host

Memory

Data router

QDIO

OSA-Express


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Data routerWith OSA-Express3, what was previously done in firmware is now performed in hardware.There is additional logic in the IBM ASIC to handle packet construction, inspection, androuting, thereby allowing packets to flow between host memory and the LAN at line speed

without firmware intervention. With the data router, the store and forward technique in DMAis no longer used, which enables a direct host memory-to-LAN flow. This avoids a hop and

is designed to reduce latency and to increase throughput for standard frames (1492 bytes)and jumbo frames (8992 bytes).

Priority queuingPriority queuing is a capability supported by the QDIO architecture and introduced with the

Service Policy Server (for z/OS environments only). It sorts outgoing IP message trafficaccording to the service policy you have set up for the specific priority assigned in the IPheader.

This is an alternative to the best effort priority assigned to all traffic in most TCP/IP networks.Priority queuing allows the definition of four different priority levels for TCP/IP traffic through

the OSA features defined for QDIO. For example, you can grant interactive communicationsthe highest priority while assigning batch traffic the lowest, with two additional categories inbetween, perhaps based on particular user groups or projects.

QDIO uses four write (outbound) queues and one read (inbound) queue for each TCP/IPstack sharing the OSA feature.

OSA signals to z/OS Communications Server when there is work to do. z/OSCommunications Server puts outbound packets in one of the four queues, based on priority

settings.

At a certain time, z/OS Communications Server signals the OSA feature that there is work to

do. The OSA feature searches the four possible outbound queues by priority and sends thepackets to the network, giving more priority to queues 1 and 2, and less priority to queues 3and 4.

For example, if there is data on every queue, queue 1 is served first, then portions of queue 2,then fewer portions of queue 3, then even fewer portions of queue 4, and then back to

queue 1. This means that if there were four transactions running across the four queues, overtime queue 1 would finish first, queue 2 would finish second, and so on.

Dynamic OSA Address Table (OAT) updateWith QDIO, this process simplifies installation and configuration tasks. The definition of IP

addresses is done in one place, the TCP/IP profile, thus removing the requirement to enterthe information into the OAT using the OSA Support Facility (OSA/SF).

The OAT entries will be dynamically built when the corresponding IP device in the TCP/IPstack is started.

At device activation, all IP addresses contained in the TCP/IP stacks IP HOME list aredownloaded to the OSA, and corresponding entries are built in the OAT. Subsequent changes

to these IP addresses will cause a corresponding update of the OAT.

Note:With OSA-Express3 and OSA-Express2, priority queuing is by default enabled; this

reduces the total number of supported TCP/IP stacks and devices (see Maximum TCP/IPstacks and subchannels on page 8).


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LPAR-to-LPAR communicationAccess to an OSA port can be shared among the system images that are running in thelogical partitions to which the channel path is defined to be shared. Also, access to a port canbe shared concurrently among TCP/IP stacks in the same logical partition or in different

logical partitions.

When port sharing, an OSA port operating in QDIO mode has the ability to send and receiveIP traffic between logical partitions without sending the IP packets out to the LAN and thenback to the destination logical partition.

For outbound IP packets, the OSA port uses the next-hop IP address within the packet todetermine where it is sent. If the next-hop IP address had been registered by another TCP/IP

stack sharing the OSA port, then the packet will be sent directly to that TCP/IP stack, and notonto the LAN. This makes the forwarding of IP packets possible within the same host system.

Internet Protocol Assist (IPA) functionsOSA QDIO assists in IP processing and offloads the TCP/IP stack functions for the following:

Multicast support (see TCP/IP multicast and broadcast support on page 15)

Broadcast filtering (see TCP/IP multicast and broadcast support on page 15) Building MAC and LLC headers Address Resolution Protocol (ARP) processing (see ARP cache management on

page 16) Checksum offload (see Checksum offload support for z/OS and Linux on System z on

page 17)

QDIO functionsThe following QDIO functions are supported on z10 an z9 servers:

TCP/IP functions

Large Send for TCP/IP traffic for OSA-Express3 and OSA-Express2 (see Large send forTCP/IP traffic on page 11)

640 TCP/IP stacks (see Maximum TCP/IP stacks and subchannels on page 8)

Concurrent LIC update

The OSA features have increased memory to facilitate concurrent application of LIC updates,

allowing the application of LIC updates without requiring a configuration off/on, therebyminimizing the disruption of networking traffic during the update.

Concurrent LIC update applies to the OSA-Express3 and OSA-Express2 features(1000BASE-T Ethernet, Gigabit Ethernet SX, Gigabit Ethernet LX, 10 Gigabit Ethernet SR,and 10 Gigabit Ethernet LR). It is offered for the QDIO and OSA for NCP mode only (CHPID

type OSD and OSN).

Hardware assistsComplementary virtualization technology is available, which includes:

QDIO Buffer-State Management (QEBSM) - Two hardware instructions help to eliminate

the overhead of hypervisor interception.

Host Page-Management Assist (HPMA) - An interface to the z/VM central storagemanagement function designed to allow the hardware to assign, lock, and unlock page

frames without z/VM hypervisor assistance.

These hardware assists allow a cooperating guest operating system to initiate QDIOoperations directly to the applicable channel, without interception by z/VM, thereby helping to


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provide additional performance improvements. Support is integrated in System z Licensed

Internal Code.

QDIO Diagnostic Synchronization for z/OS

QDIO Diagnostic Synchronization is exclusive to System z, and the OSA-Express3 and

OSA-Express2 features when configured as CHPID type OSD (QDIO). It is designed to

provide the system programmer and network administrator with the ability to coordinate andsimultaneously capture both operating system (software) and OSA (hardware) traces at thesame instance of a system event. This allows the host operating system to signal the

OSA-Express3 and OSA-Express2 feature to stop traces and capture the current tracerecords. Using existing tools (traps) and commands, the operator can capture both hardwareand software traces at the same time, and then correlate the records during post processing.

OSA-Express Network Traffic Analyzer for z/OS

OSA-Express Network Traffic Analyzer is exclusive to System z and the OSA-Express3 andOSA-Express2 features when configured as CHPID type OSD (QDIO). It allows trace records

to be sent to the host operating system to improve the capability to capture data for both thesystem programmer and the network administrator. This function allows the operating systemto control the sniffer trace for the LAN and capture the records into host memory and storage,

using existing host operating system tools to format, edit, and process the sniffer records.

For more information, refer to Appendix B, OSA-Express Network Traffic Analyzer onpage 197.

1.1.3 Non-QDIO mode

Like any other channel-attached control unit and device, an OSA CHPID can execute channelprograms (CCW chains) and present I/O interrupts to the issuing applications. For non-QDIO

mode, the OSA CHPIDs are defined as channel type OSE. The non-QDIO mode requires theuse of the OSA/SF for setup and customization of the OSA features.

The 1000BASE-T features support non-QDIO mode. This mode supports SNA/APPN/HPRand TCP/IP traffic simultaneously through the OSA CHPID. The non-QDIO mode types areas follows:

TCP/IP PassthruIn TCP/IP Passthru mode, an OSA feature transfers data between a TCP/IP stack to which itis defined and clients on an Ethernet 10/100/1000 Mbps LAN that is attached to the port on a

1000BASE-T feature and supports one of the following frame protocols:

Ethernet II using the DEC Ethernet V 2.0 envelope Ethernet 802.3 using the 802.2 envelope with SNAP

For TCP/IP Passthru mode, the default OAT may be used. In that case, no configuration orsetup is required. See Appendix F, TCP/IP Passthru mode on page 251details.

SNA/APPN/HPR supportIn this mode, an OSA feature acts as an SNA Passthru agent to clients that use the SNAprotocol on the LAN that is directly attached to the OSA-Express. If an OSA feature is running

in the SNA mode, it is viewed by VTAM as an external communications adapter (XCA) thatcan have either switched or non-switched lines of communication.


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1.1.4 OSA addressing support

This section describes the maximum number IP addresses, MAC addresses, andsubchannels supported by the OSA features.

Maximum IP addresses per OAT

The OSA Address Table (OAT) is a component of an OSA features configuration. An OAT

entry defines the data path between an OSA feature port and a logical partition (LP) anddevice unit address. That is, it manages traffic through the OSA CHPID.

OSA-Express features support a maximum of 2048 IP addresses (IPv4, IPv6, and VIPA) per

CHPID, while OSA-Express3 and OSA-Express2 features support up to 4096 IP addressesper CHPID.

When the OSA CHPID is defined in QDIO mode, the OAT table entries are built and updated

dynamically.

Maximum number of media access control (MAC) addresses

When configured as OSD, up to 2048 MAC or virtual (VMAC) addresses are supported per

CHPID with OSA features. Included in the maximum number of MAC addresses is theburnt-in MAC address of the OSA port.

The MAC or VMAC addresses are added to the Layer 2 table of the OAT when the TCP/IPstacks (in which the addresses are defined) are started.

Also see Layer 2 support on page 18and Layer 3 VMAC for z/OS on page 20.

Maximum TCP/IP stacks and subchannels

A subchannel is a logical representation of a device. One subchannel is assigned to each

device defined to the logical partition. Therefore, if you are sharing an OSA CHPID across 15LPs and define one device, that device uses 15 subchannels.

The maximum number of supported TCP/IP stacks and subchannels on System z10 andSystem z9 servers are as follows:

OSA CHPID in non-QDIO mode (type OSE)

An OSA CHPID in non-QDIO mode is capable of supporting up to 120 TCP/IP stacks and

240 subchannels for all System z servers.

OSA CHPID in QDIO mode (type OSD)

The OSA features support 640 TCP/IP stack connections per dedicated CHPID, or 640

total stacks across multiple logical partitions using a shared or spanned CHPID. Themaximum number of subchannels allowed is 1920 (1920 subchannels / 3 = 640 stacks).

Note:By default, OSA-Express3 and OSA-Express2 have multiple priorities for outbound

queues enabled (four QDIO priorities). This means the maximum number of supportedsubchannels is reduced to 480 (1920 subchannels / 4 = 480 subchannels), thus reducingthe total number of supported TCP/IP stacks to 160 (480 subchannels / 3 = 160 stacks).

Priority queues can be disabled via HCD/IOCP. For example, in IOCP use theCHPARM=02 value to disable priority queuing.


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1.1.5 OSA/SF support

OSA/SF includes a Java-based Graphical User Interface (GUI) in support of the clientapplication. The Java GUI is independent of any operating system or server (transparent to

the operating system), and is expected to operate wherever the current Java runtimes areavailable.

Use of the GUI is optional; a REXX command interface is also included with OSA/SF. OSA/SFis not required to set up the OSA features in QDIO mode (CHPID type OSD), but it can beused for monitoring and controlling ports. OSA/SF has been, and continues to be, integrated

in z/OS, z/VM, and z/VSE, and runs as a host application. For OSA/SF, Java GUIcommunication is supported via TCP/IP only. In the past, communication was supported via

EHLLAPI (3270), APPC, and TCP/IP.

This integrated version of OSA/SF is a complete replacement for the currently integrated

versions in z/OS, z/VM, and z/VSE. This version of OSA/SF is not being offered as aseparately orderable program product.

The Open Systems Adapter Support Facility (OSA/SF) is used primarily to:

Manage all OSA ports. Configure all OSA non-QDIO ports. Configure local MAC. Display registered IPv4 addresses (in use and not in use). It is supported on System z

servers for QDIO ports. Display registered IPv4 or IPv6 Virtual MAC and VLAN ID associated with all OSA

Ethernet features configured as QDIO Layer 2. Provide status information about an OSA port - its shared or exclusive use state.

OSA/SF is an integrated component of z/VM.

This support is applicable to all OSA features on System z servers.

With z/OS, a second interface using a set of REXX EXECs through the Time Sharing OptionExtensions (TSO/E) can be used to control the OSA features defined to System z servers onwhich the TSO/E is running.

OSA/SF is not always required to customize an OSA feature, but is highly recommended to

gather operational information and to assist in problem determination. The OSA/SF Query

function provides performance information about the OSA CHPIDs.

OSA/SF is not required to configure the OSA features in operating modes OSD, OSC, and

OSN.

For details regarding OSA/SF, the GUI, and REXX EXECs, refer to Chapter 4, Setting up and

using OSA/SF on page 47and Appendix E, Using the OSA/SF REXX interface onpage 241.

1.2 OSA capabilities

This section discusses the capabilities that exploit the OSA-Express3 and OSA-Express2features.


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1.2.1 Virtual IP address (VIPA)

In the TCP/IP environment, VIPA frees TCP/IP hosts from dependence on a particularnetwork attachment, allowing the establishment of primary and secondary paths through the

network. VIPA is supported by all of the OSA features.

An IP address traditionally ties to a physical link at one end of a connection. If the associated

physical link goes down, it will be unreachable. The Vir tual IP Address, on the other hand,exists only in software and has no association to any physical link. The TCP/IP stack is thedestination IP address instead of the network attachment.

VIPA provides for multiple IP addresses to be defined to a TCP/IP stack, allowing

fault-tolerant, redundant, backup paths to be established. Applications become insensitive tothe condition of the network since the VIPA will always be active, enabling users to routearound intermediate points of failure in the network.

VIPA Takeover and Takeback

Since a VIPA is associated with a TCP/IP stack and not a physical network attachment, it canbe moved to any TCP/IP stack within its network. If the TCP/IP stack that the VIPA is on fails

(due to an outage), the same VIPA can be brought up automatically on another TCP/IP stack(VIPA Takeover) to allow end users to reach the backup server and applications. The originalsession between the end user and original server is not disrupted. Once the failed TCP/IP

stack is restored, the same VIPA can be moved back automatically (VIPA Takeback).

1.2.2 Primary/secondary router function

The primary/secondary router function enables an OSA port to forward packets with unknownIP addresses to a TCP/IP stack for routing through another IP network interface, such as

HiperSockets or another OSA feature.

In order for an OSA port to forward IP packets to a particular TCP/IP stack for routing to its

destination, the PRIRouter must be defined on the DEVICE statement in the TCP/IP profile.

If the TCP/IP stack that has an OSA port defined as PRIRouter becomes unavailable, then a

second TCP/IP stack, defined as the secondary router (SECRouter on the DEVICE statementin the TCP/IP profile), will receive the packets for unknown IP addresses.

For enhanced availability, the definition of one primary router and multiple secondary routers

for devices on an OSD-type CHPID is supported; however, only one secondary router issupported for devices on an OSE-type CHPID.

1.2.3 IPv6 support

Internet Protocol Version 6 (IPv6) is supported by the OSA features when configured in QDIO

mode. IPv6 is the protocol designed by the Internet Engineering Task Force (IETF) to replaceInternet Protocol Version 4 (IPv4). IPv6 provides improved traffic management in the following

areas:

Important:Sharing a single OSA port can fail in Load Balancing solutions. Acircumvention is to use GRE or NAT, which can have a negative effect on performance.Layer 3 virtual MAC is a function available on System z servers with OSA-Express. For

more detailed information about Layer 3 VMAC for z/OS refer to Layer 3 VMAC for z/OS

on page 20


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128bit addressing

Eliminates all practical limitations on global address ability. This means that private

address spaceand the network address translators (NATs) used between privateintranet and public Internetare no longer needed.

Simplified header formats

Allow for more efficient packet handling and reduced bandwidth cost. Hierarchical addressing and routing

Keep routing tables small and backbone routing efficient by using address prefixes rather

than address classes.

Improved support for options

Changes the way IP header options are encoded, allowing more efficient forwarding and

greater flexibility.

Address auto-configuration

Allows stateless IP address configuration without a configuration server. In addition, IPv6

brings greater authentication and privacy capabilities through the definition of extensions,

and integrated Quality of Service (QoS) through a traffic class byte in the header.

1.2.4 Large send for TCP/IP traffic

Large send can improve performance by offloading TCP packet processing from the host tothe OSA-Express3 or OSA-Express2 features running in QDIO mode. Offload allows the host

to send large blocks of data (up to 64 kilobytes) directly to the OSA-Express3 orOSA-Express2 feature. The OSA-Express3 or OSA-Express2 feature then fragments those

large blocks into standard Ethernet frames (1500 bytes) to be sent out on the LAN (seeFigure 1-3).

Figure 1-3 Large send versus standard Ethernet and Jumbo frame sizes

Large send supports outbound IPv4 traffic only, and applies solely to unicasts. Large sendsupport reduces host processor utilization, returning CPU cycles for application use while

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

Ethernet

frame

Jumbo

frame

TCP large

send

.

.

.

.

Applicationsend buffer

TCP Stack

OSA-Express2or

OSA-Express3

63 KB 63 KB 63 KB

1.5 KB

1.5 KB

1.5 KB

1.5 KB

1.5 KB

1.5 KB

9 KB

9 KB

9 KB

9 KB

63 KB


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increasing network efficiencies. Large send applies only to the OSA-Express3 and

OSA-Express2 features.

Large send can be enabled by specifying the SEGMENTATIONOFFLOAD parameter withinthe GLOBALCONFIG block in your TCPIP profile member. The default is

NOSEGMENTATIONOFFLOAD.

For more information about large send for Linux on System z, refer to:

http://www.software.ibm.com/developerworks/opensource/linux390

Large send support is also available with z/OS.

1.2.5 VLAN support

Virtual Local Area Network (VLAN) is supported by the OSA-Express3 and OSA-Express2

features when configured in QDIO mode. This support is applicable to z/OS, z/VM, and Linuxon System z environments.

The IEEE standard 802.1q describes the operation of Virtual Bridged Local Area Networks. AVLAN is defined to be a subset of the active topology of a Local Area Network. The OSA

features provide for the setting of multiple unique VLAN IDs per QDIO data device. They alsoprovide for both tagged and untagged frames to flow from an OSA port. The number of

VLANs supported is specific to the operating system.

VLANs facilitate easy administration of logical groups of stations that can communicate asthough they were on the same LAN. They also facilitate easier administration of moves, adds,and changes in members of these groups. VLANs are also designed to provide a degree of

low-level security by restricting direct contact with a server to only the set of stations that

comprise the VLAN.

With System z servers, where multiple TCP/IP stacks exist, potentially sharing one or moreOSA features, VLAN support is designed to provide a greater degree of isolation (seeFigure 1-4 on page 13).

Tip: Applications that use large TCP send buffers will obtain the most benefit from largesend.
http://www.software.ibm.com/developerworks/opensource/linux390http://www.software.ibm.com/developerworks/opensource/linux390http://www.software.ibm.com/developerworks/opensource/linux390


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Figure 1-4 VLAN support

VLAN support for z/OS

Full Virtual Local Area Network (VLAN) support is offered for all OSA Ethernet features

available on System z servers. z/OS Communications Server supports Virtual Local AreaNetwork Identifications (VLAN IDs). Support is offered for up to eight global VLAN IDs perOSA port, based on the IP version:

Eight Global VLAN (IDs) for IPv4 Eight Global VLAN (IDs) for IPv6

VLAN support for z/VM

z/VM exploits the VLAN technology and conforms to the IEEE 802.1q standard. Support is

offered for one global VLAN ID per OSA port, based on the IP version:

One Global VLAN (ID) for IPv4 One Global VLAN (ID) for IPv6

The z/VM TCP/IP stack supports one VLAN ID per OSA port. Each port can be configuredwith a different VLAN ID.

VLAN support for Linux on System z

VLAN support in a Linux on System z environment is available for the OSA Ethernet features

operating in QDIO mode.

For Linux on System z support, refer to the following Web site for further information:

http://www.ibm.com/developerworks

VLAN support of GVRP

GVRP is defined in the IEEE 802.1p standard for the control of IEEE 802.1q VLANs. It can beused to help simplify networking administration and management of VLANs.

Common physical network

LP 1

z/OS TCP/IP

IPv4

VLAN 28

OSA-Express Ethernetports in QDIO mode

port 1

LP 2

z/OS TCP/IP

IPv4 IPv6

VLAN16 VLAN37

LP 3

Linux TCP/IP

IPv6 IPv4

VLAN37 VLAN4

LP 4

z/VM TCP/IP

IPv4

VLAN12

VLAN28 VLAN16 VLAN4 VLAN12

port 2

Ethernet Switch


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With GVRP support, an OSA-Express3 or OSA-Express2 port can register or de-register its

VLAN IDs with a GVRP-capable switch and dynamically update its table as the VLANschange (Figure 1-5).

Figure 1-5 GVRP support

Support of GVRP is exclusive to System z. It is applicable to all of the OSA-Express3 andOSA-Express2 features when in QDIO mode (CHPID type OSD), and is supported by z/OSand z/VM.

More information on VLAN support can be found in Chapter 10, VLAN support on page 131.

1.2.6 SNMP support for z/OS and Linux on System z

SNMP is supported for all of the OSA features when configured in the QDIO mode (CHPIDtype OSD). The OSA SNMP subagent support offered via the OSA features LIC includes:

Get and GetNext requests

This support applies to all OSA features supported on System z servers.

dot3StatsTable

Ethernet data for dot3StatsTable applies to all of the Ethernet features supported onSystem z servers. It implements the SNMP EtherLike Management Information Base

(MIB) module in RFC 2665, which provides statistics for Ethernet interfaces. Thesestatistics can assist in the analysis of network traffic congestion.

Performance data

This support applies to all of the OSA features supported on System z servers. Theperformance data reflects the OSA utilization.

Traps and Set

This support applies to all of the OSA features supported on System z.

SNMP support for LAN Channel Station (LCS) applies to all of the OSA features

supported on System z, in conjunction with TCP/IP applications only. It supports the sameSNMP requests and alerts offered in QDIO mode (Get, GetNext, Trap, and Set), and isexclusive to the z/OS environment.

Physical LAN

OSA-Express2

VLAN22VLAN33

VLAN44GVRP supportdynamically registersVLAN IDs to thephysical LAN

VLAN44

Physical LAN

OSA-Express3

VLAN22VLAN33

VLAN44GVRP supportdynamically registersVLAN IDs to thephysical LAN

VLAN 22 VLAN33


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For more information about SNMP support, refer to:

http://www.ibm.com/servers/eserver/zseries/networking/dsnmp.html

Open Systems Adapter Support Facility is not required to manage SNMP data for the OSAfeatures. An SNMP subagent exists on an OSA feature, which is part of a direct path betweenthe z/OS or Linux on System z master agent (TCP/IP stacks) and an OSA-Express

Management Information Base (MIB).

The OSA features support an SNMP agent by providing data for use by an SNMPmanagement application, such as Tivoli NetView. This data is organized into MIB tables

defined in the TCP/IP enterprise-specific MIB, as well as standard RFCs. The data issupported by the SNMP TCP/IP subagent (see Figure 1-6).

Figure 1-6 SNMP support - z/OS example

1.2.7 TCP/IP multicast and broadcast support

Multicast and broadcast support is part of the Internet Protocol assist (IPA) function of the

OSA feature.

Multicast support

For sending data to multiple recipients, OSA features support IP multicast destinations only inQDIO or IP Passthru mode.

TCP/IP broadcast support for z/OS, z/VM, and Linux on System z

Broadcast support is included for all of the OSA features when configured in QDIO mode andsupporting the Routing Information Protocol (RIP) Version 1. Broadcast is also supported for

all of the OSA features when carrying TCP/IP traffic and configured in the non-QDIO mode(LAN Channel Station - LCS mode).

Tip:If you subscribe to the document OSA-Express Direct SNMP MIB module through

Resource Link, you will receive e-mail notification of document changes.

OSNMPD

SNMP Agent's

Address Space

z/OS

System z

OSA-Express

UNIX Shell

User's Address

Space

osnmpcommand

Managers (clients)

z/OS

Agents (servers)

OSAD

device

with

subagent

OSA proxy

Subagent

Tivoli NetView

Address Space

SNMP command

TCP/IP

Address Space

TCP

SNMP Subagent
http://www.ibm.com/servers/eserver/zseries/networking/dsnmp.htmlhttp://www.ibm.com/servers/eserver/zseries/networking/dsnmp.html


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A broadcast simultaneously transmits data to more than one destination; messages are

transmitted to all stations in a network (for example, a warning message from a systemoperator). The broadcast frames can be propagated through an OSA feature to all TCP/IPapplications that require broadcast support, including applications using RIP V1.

1.2.8 ARP cache management

The query and purge ARP enhancements are supported for all OSA features when

configured in QDIO mode. The OSA feature maintains a cache of recently acquiredIP-to-physical address mappings (or bindings). When the binding is not found in the ARPcache, a broadcast (an ARP request How can I reach you?) to find an address mapping is

sent to all hosts on the same physical network. Because a cache is maintained, ARP does nothave to be used repeatedly, and the OSA feature does not have to keep a permanent record

of bindings.

Query ARP table for IPv4 for Linux on System z

The Query ARP table is supported using Internet Protocol Version 4 (IPv4). The TCP/IP stackalready has an awareness of Internet Protocol Version 6 (IPv6) addresses.

Purge ARP entries in cache for IPv4 for z/OS and Linux on System zPurging of entries in the ARP cache is supported using IPv4. The TCP/IP stack already has

an awareness of IPv6 addresses.

ARP takeover

ARP takeover provides the capability of switching OSA port operations from one OSA toanother OSA running in the same mode in z/OS environments.

When z/OS TCP/IP is started in QDIO mode, it downloads all the home IP addresses in the

stack and stores them in each OSA feature to which it has a connection. This is a service ofQDIO architecture and only occurs automatically for OSD channels. For OSA ports set up as

OSE channels (non-QDIO), you must define multiple IP addresses in the OSA Address Table

using OSA/SF. The OSA then responds to ARP requests for its own IP address, as well as forvirtual IP addresses (VIPAs). If an OSA feature fails while there is a backup OSA available onthe same network or subnetwork, TCP/IP informs the backup OSA which IP addresses (realand VIPA) to take over, and the network connection is maintained. Note that for this to work,

multiple paths must be defined to the TCP/IP stack. For example, MULTIPATH must bedefined to the IPCONFIG statement of the TCP/IP profile in z/OS. See Appendix H, ARP

takeover on page 269for more information.

ARP statistics

QDIO includes an IP assist (IPA) function, which gathers Address Resolution Protocol (ARP)data during the mapping of IP addresses to media access control (MAC) addresses. CHPIDs

defined as OSD maintain ARP cache information in the OSA feature (ARP offload). This isuseful in problem determination for the OSA feature.

Note that not all OSA features provide ARP counter statistics and ARP cache information to

TCP/IP.

1.2.9 IP network availability

There are several ways to ensure network availability, should failure occur at either the logical

partition or the CHPID/network connection level. Port sharing, redundant paths, and the useof primary and secondary ports all provide some measure of recovery. A combination of these

can guarantee network availability regardless of the failing component.


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When TCP/IP is started in QDIO mode, it downloads all the home IP addresses in the stack

and stores them in the OSA feature. This is a service of QDIO architecture. The OSA portthen responds to ARP requests for its own IP address, as well as for virtual IP addresses(VIPAs). If an OSA feature fails while there is a backup OSA available on the same network or

subnetwork, TCP/IP informs the backup OSA port which IP addresses (real and VIPA) to takeover, and sends a gratuitous ARP that contains the MAC address of the backup

OSA-Express. The network connection is maintained.

1.2.10 Checksum offload support for z/OS and Linux on System z

z/OS and Linux on System z environments provide the capability of calculating and validating

the Transmission Control Protocol/User Datagram Protocol (TCP/UDP) and Internet Protocol(IP) header checksums. Checksums are used to verify the contents of files when transmitted

over a network. For example:

OSA will validate the TCP, UDP, and IP header checksums for inbound packets. OSA will calculate the TCP, UDP, and IP header checksums for outbound packets.

Checksum offload is supported by all OSA Ethernet features when operating in QDIO mode.

By offloading checksum processing to the supporting OSA features, host server cycles arereduced, which can result in improved performance for most IPv4 packets.

When checksum is offloaded, the OSA feature performs the checksum calculations.

Therefore, this function only applies to packets which actually go onto the LAN or come infrom the LAN. When multiple IP stacks share an OSA port, and an IP stack sends a packet to

a next hop IP address owned by another IP stack sharing the same OSA port, OSA sends theIP packet directly to the other IP stack without placing it out on the LAN. Checksum offload

does not apply to such IP packets.

Checksum offload does not apply to IPv6 packets. TCP/IP will continue to perform allchecksum processing for IPv6 packets. This function does not apply to ICMP checksumprocessing. TCP/IP will continue to perform processing for ICMP checksum.

Checksum offload support is available with z/OS.

For Linux on System z support, refer to the following Web site for further information:

http://www.ibm.com/developerworks

Dynamic LAN idle for z/OS

Dynamic LAN idle is exclusive to System z servers and applies to the OSA-Express3 andOSA-Express2 features (CHPID type OSD), and is supported by z/OS.

Dynamic LAN idle is designed to reduce latency and improve networking performance by

dynamically adjusting the inbound blocking algorithm. When enabled, the z/OS TCP/IP Stackwill adjust the inbound blocking algorithm to best match the application requirements.

For latency sensitive applications, the blocking algorithm is modified to be latency sensitive.

For streaming (throughput sensitive) applications, the blocking algorithm is adjusted tomaximize throughput. In all cases, the z/OS TCP/IP stack dynamically detects the applicationrequirements, making the necessary adjustments to the blocking algorithm. The monitoring of

the application and the blocking algorithm adjustments are made in real-time, dynamicallyadjusting the applications LAN performance.

Note: Linux on System z only supports inbound checksum offload (inbound packets).
http://www.ibm.com/developerworkshttp://www.ibm.com/developerworks


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System administrators can authorize the z/OS TCP/IP stack to enable a dynamic setting,

which was previously a static setting. The z/OS TCP/IP stack dynamically determines thebest setting for the current running application, based on system configuration, system,inbound workload volume, CPU utilization, traffic patterns, and other related items.

1.2.11 Layer 2 support

The OSA Ethernet features on System z servers can support two transport modes of the OSI

model: Layer 2 (Link Layer or MAC Layer) and Layer 3 (Network Layer). The Layer 2 transportmode allows for communication with IP and non-IP protocols. OSA works in conjunction witheither z/VM TCP/IP or Linux on System z Layer 2 support running in a Logical Partition or as

a z/VM guest.

The z/VM virtual switch can also be used to enable Layer 2 functionality for guest systems;

this is illustrated in Figure 1-7.

Figure 1-7 Layer 2 support for OSA-Express

The virtual switch exploits both Layer 2 and Layer 3 support in the z/VM Control Program. ForLayer 2 support, the z/VM Control Program owns the connection to the OSA feature and

manages the MAC addresses and VLAN connectivity of the attached guest systems. Thevirtual switch performs automatic MAC address generation and assignment to allowuniqueness across the z/VM guest systems. MAC addresses can also be locally

administered.

The virtual switch uses each guest systems unique MAC address to forward frames. Data is

transported and delivered within Ethernet frames, providing the ability to transport both IPand non-IP (for example, NetBIOS and SNA) frames through the fabric that the virtual switchsupports. Through the address-resolution process each guest systems MAC address

becomes known to hosts residing on the physical side of the LAN segment. All inbound oroutbound frames passing through the OSA port have the guest systems corresponding MAC

address as the source or destination address.

The OSA Ethernet features can filter inbound frames by Virtual Local Area Networkidentification (VLAN ID, IEEE 802.1q), the Ethernet destination MAC address, or both.

02-00-00-00-00-01

z/VM

guest

Virtual Switch (Layer 2)

Linux

guest

Linux

OSA-Express

02-00-00-00-00-02

02-00-00-00-00-03

z/VM

02-00-00-00-00-01

02-00-00-00-00-02

02-00-00-00-00-03

NetBIOS

Appl.

SNA

Appl.

TCP/UDP

Appl.

EthernetSwitch


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Filtering can reduce the amount of inbound traffic being processed by the operating system,

helping to reduce CPU utilization. Filtering by VLAN ID or MAC address can also allow you toisolate portions of your environment that have sensitive data, thereby providing a degree oflow-level security.

Link aggregation for z/VM in Layer 2 mode

Link aggregation is exclusive to System z and is applicable to the OSA-Express2 andOSA-Express3 features in Layer 2 mode when configured as CHPID type OSD (QDIO), andis supported by z/VM.

z/VM virtual switch-controlled (VSWITCH-controlled) link aggregation (IEEE3 80

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