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Introduction to the Mainframe: Networking basics
Chapter 1 Mainframes and Networks
Objectives • Understand the role of the network in your company's business objectives and corporate infrastructure. • After completing this chapter, you will be able to: • Explain the use of data networks in high volume industry transaction processing • List at least three typical advantages of a mainframe in network communications • Describe the role of a network administrator in a large network • List the major software components of the z/OS Communications Server.
Key Terms • Connectivity • Integrated supply chain • Network • OSI • Extranet • Internet • Network Protocol • OSA • APPN • Fiber optics • Intranet • OLTP • Backbone • Infrastructure • Mainframe
Mainframes, networks, and you • What is a network? • Definition depends on who is using the network • IT Professional • Engineer • Our definition of a network • Where are mainframes used today? • ATMs • Credit Card Payments • Online Purchasing
Networks and online systems • Categories of Networks • Internet • Intranet • Extranet • Terminals • Online Transaction processing • Characteristics of OLTP • What activities add to network traffic?
The importance of networks • Why are networks important? • Satisfy an objective or need. • Provide a means for transmitting data. • Accuracy and speed is essential to business • Numerous businesses depend on their networks. • Examples of mainframe-based networks • 1.4.1 ATM Cash withdrawal • 1.4.2 Credit purchase at a retail store • 1.4.3 Technology choices abound in network technology
Who supports the network? • Separated into hardware and software • Network administrator is responsible for both • Responsibilities of a Network Administrator • Definition, maintenance, and modification of an existing z/Series network • Problem, isolation, and correction • Performance tuning • Capacity planning recommendations • Development of operational procedures • Training of network operators
What are basic elements of a data network? • Basic elements are hardware, software, and protocols. • What is a network infrastructure? • Protocols • “Traffic Rules” of the network • Define how two devices in a network communicate • Layered network architecture model.
Overview of System z network capabilities • System z is capable of handling many network nodes that are dispersed over a large area. • Internal network capabilities. • Guest machines • LPARs • Cluster • External network capabilities • TCP/IP applications, protocols, and equipment • Subarea System Network Architecture • Advanced Peer-to-Peer Networking • Integration of SNA into IP networks using EE
z/OS Communication Server • Implements the SNA and TCP/IP protocols. • Provides a set of protocols to support peer-to-peer connectivity. • Performance enhancements that can benefit a variety of TCP/IP applications.
SNA and TCP/IP on z/OS • What is SNA? • When were the protocols developed? • What is the advantage of SNA? • Why is TCP/IP more popular?
Data integrity, security, and availability in a network • Data Integrity • Modification • Non-repudiation • Error-free transmission • Security • Procedures • Preventing unauthorized disclosure of transmitted data • Detecting unauthorized modification of data • Non-repudiation using proof of origin, receipt, and digital certificates. • Products • IBM Security Server and Commutations Server components include RACF and Farewell. • Communications server components include parameters to encrypt network traffic • Major IBM subsystems have security mechanisms. • Availability • Degree to which a system is ready when needed to process data. • Enhance availability through redundancy. • Parallel Sysplex
Summary • A network is the hardware and software that enables computers to share files and resources and exchange data. • To support changing requirements protocols such as SNA and TCP/IP can be combined to optimize performance. • z/OS network capability includes a fully-featured communications server with integration of SNA and TCP/IP protocols. • Many technologies exists to protect data between the server and authorized clients.
Chapter 2 Network Protocols
Objectives • This chapter discusses various networking protocols.
Network protocols • Point to point - direct link between two hosts • Point to multipoint - direct link from one point to many others • Broadcast - multi-access with ability to address all hosts on the network • Local Area Network - LAN segment • Wide Area Network (WAN)
Local Area Network (LAN) Ethernet • Ethernet is believed to consist of 90% of network installations. • Standard defined in 1985 known as IEEE 802.3 • CSMA/CD access method • Ethernet 10 mbps • Fast Ethernet 100 mbps • Dual Speed Products • Gigabit Ethernet • Retains the standard 10/100 base-T and CSMA/CD but it uses the fiber channel’s physical layer as the underlying transport mechanism • Full Duplex does not require the CSMA/CD scheme, but retains support for the Ethernet frame format.
Wide area networking • Network Interface Card (NIC) • Wide Area Networking (WAN) • The subscriber loop • What is a subscriber loop? • Asymmetric Digital Subscriber Line (ADSL) • Integrated Services Digital Network (ISDN) • ISDN Basic rate interface (BRI) • ISDN primary rate interface (PRI) • WAN Connection type • Point to Point • Circuit switching • T1/E1 • Packet switching • Frame relay
Network routing • Static - manual entry of routes into a table • Dynamic – populating routing tables by protocols • Routing Information Protocol (RIP) • Open Shortest Path First (OSPF)
Security • Firewalls and gateways • Security protocols • Protection
Summary • Understand the terminology • Understand the layers • physical layer • data link layer (Ethernet) • network layer (IP and routing) • transport layer (TCP and UDP)
Chapter 3 Network Hardware on the Mainframe
Objectives • Understand the different types of network links • Explain why OSA-Express is the future direction for network connectivity • Set the different OSA modes • Explain how to associate protocols with the OSA-Express
Key Terms • Osd • Ccl • Parallel • OSA • LPAR • NCP • HiperSocket • Escon • Ose • VLAN • Qdio • Escon Converter
The System z channel subsystem and network links • Each server has a channel subsystem • The CSS allows channel I/O operations to continue independently of other operations. • The purpose is to permit a z990 system to have more than 256 channels • Components • Logical partition name • Logical partition identifier • MIF Image ID • Physical Channel ID • Channel ID • Control Unit • I/O Device
Hardware channels • Parallel Channel • Byte Multiplexer • Block Multiplexer • Enterprise System Connectivity Channel
Hardware channels • Open Systems Adapter • Integrates several hardware features and supports many networking transport protocols • Three main versions • OSA-Express 2 • OSA-Express • OSA-2 • QDIO verses non-QDIO • QDIO incorporates a number of features: • LPAR-to-LPAR • DMA (Direct Access Memory) • Priority queuing • Enhanced IP network availability • VLAN Support • ARP Takeover • Communication Controller for LINUX (CCL)
HiperSockets • Provides high-speed TCP/IP connectivity within a Central Electronics Complex. • Based on the OSA-Express queued direct input/output protocol. • HiperSockets with CHIPD FC • HiperSockets with CHPID FD • HiperSockets with CHPID FE • HiperSockets with CHIPID FF
Summary The mainframe originally relied upon the channel subsystem to offload I/O processing to channel programs. DASD is still accessed using FICON and ESCON channels, but for networking connectivity, OSA-Express cards offer better performance and availability.
Chapter 4 Sample Configuration
Objectives • The objective of this chapter is to provide an introduction to the type of System z networking components and environment that many organizations deploy • After completing this chapter, you will be able to: • List the components of a typical System z networking infrastructure • Give three reasons why organizations implement this type of configuration.
Key Terms • RAS • Service Level Agreement (SLA) • Stub Area • Sysplex • Switch • VIPA • VTAM • CF • CICS • CPC • DB2 • LPAR • OSA • OMPROUTE
Example case • Requirements for a reliable network • The ZOS Company data center • Processing is divided up physically by central processor complexes and logically by logical partitions. • Production LPAR • Development LPAR • Systems programming LPAR • Fencing off the Production LPARs • Key mainframe network availability aspects • Reliability, availability, serviceability (RAS) • Component Failure • Dual and Diverse Paths • Performance • Failure Process • Security • Scalability • Continuing compatibility • Evolving architecture
Continued • Hardware Availability • Switches • OSA Cards • CPC • Coupling Facility • Software Availability • OSPF • TCP/IP • VTAM
Summary • Organizations run many of their mission-critical applications on System z and system availability is a key factor in maintain an organization’s business. • Key Points • Most organizations will have two central processor complexes (CPCs) to allow for scheduled and unscheduled outages • Most organizations will have a geographically isolated site to allow for a disaster recover situations • OSA card can be shared among LPARs on a CPC. • TCP/IP VIPAs are not associated with a physical interface and assist in maintaining availability for applications and users.
Chapter 5 TCP/IP on z/OS
Objectives • After completing this chapter, you will be able to: • Explain the usage of the TCP/IP profile configuration file • Explain the basics of FTP and telnetd server configuration • Discuss the options for resolver configuration • List some of the most common client applications
Key Terms • Inetd • Trace Route • Receive buffer size • FTPD • EBCDIC • netstat • TCP/IP Profile • Send buffer size • Otelnetd • ASCII • Datagram Forwarding • Window Size
The heart of the matter • The TCP/IP daemon implements the IP protocol tack and runs a huge number of IP applications to the same specifications as any other operating system might do. • Control issues and the stack • A TCP/IP started task when started as a program using JCL uses a level of configurability that can’t be matched in a daemon environment. • Example: You can support more than one instance of a TCP/IP started task. • An IPv6 apology • This book uses IPv4, but System z fully supports IPv6.
The TCP/IP Profile • Sample JCL for TCP/IP task //TCPIP PROC //TCPIP EXEC PGM=EZBTCPIP, //PROFILE DD DISP=SHR,DSN=SYS1.PARMLIB(PROFILE) //SYSTCPD DD DISP=SHR,DSN=SYS1.PARMLIB(TCPDATA)
The TCP/IP Profile • Profile Statements • Link Configuration Defining links, LPAR 1 DEVICE OSAEDEV1 MPCIPA PRIROUTER LINK OSAELNK1 IPAQENET OSAEDEV1 DEVICE OSAEDEV2 MPCIPA PRIROUTER LINK OSAELNK2 IPAQENET OSAEDEV2 DEVICE VIPADEV1 VIRTUAL 1 LINK VIPALNK1 VIRTUAL 1 VIPADEV1 HOME 188.8.131.52 VIPALNK1 184.108.40.206 OSAELNK1 220.127.116.11 OSAELNK2
The TCP/IP Profile • IP Configuration • TCP Configuration • TCPMAXRCVBUFRSIZE • TCPRCVBUFRSIZE • TCPSENDBFRSIZE • Static Routing Information • Automated IP Application Monitoring
The FTP Server • Information that can be controlled in the FTP.DATA set. • Banner Page • Anonymous Configuration • Data Set Defaults • Tracing and Logging • File System • SSL/TLS • JES and DB2 environments • Character Sets • MVS and its UNIX subset
The telnet daemon • Two telnet Servers available in the z/OS environment: • TN3270 – supports line mode telnet, but is primarily used to support the TN3270 Enhanced Protocol • Z/OS UNIX Telnet server is a line mode server only. • What is inetd? • Character sets
A good resolver is hard to find • The resolver configuration file defines the operating characteristics of IP applications. • Sample resolver configuration file DOMAIN XYZ.COM • HOSTNAME MAINFRAME • NAMESERVER 18.104.22.168 22.214.171.124 • TCPIPJOBNAME TCPIP • Searching for resolver configuration information • Resolver configuration parameters can be placed in the obvious location: /etc/resolv.conf • Resolver configuration parameter can be placed in a file allocated to STSTCPD • Resolver address space • The multi-stock environment
TCP/IP clients • IP applications supported by z/OS • FTP • telnet • Ping • Tracerte or traceroute • Snmp • Netstat • Character sets
Summary • The TCP/IP started task is the engine that drives all IP based activity on z/OS. • The TCP/IP profile data set controls the configuration of the TCP/IP environment. • The FTP server implements the FTP standard and can communicate with any FTP clients on the network. • IP applications running on z/OS use a resolver configuration file for environmental values. • TCP/IP on z/OS support all of the well known server and client applications
Chapter 6 TCP/IP in a sysplex