Chapter 18

Network Communications on z/OS

Objectives

• In this chapter, you will learn:– An overview of the communication network

model layers– The software components of the z/OS

Communications Server product– The difference between a VTAM subarea and

APPN network topology– How the IP network can be used to transport

data between SNA applications.– Commonly used TCP/IP and VTAM commands

IBM Communications Server

ApplicationsApplications

Applications

z/OS

APPC

Sockets RPC

SNA

RPC

Sockets APPC

TCP/IP

Open Systems Interconnect (OSI) network model

Physical Physical Physical

Data Link Data Link Data Link Control

IP ARP RARP ICMP Network Path Control

TCP UDP Transport Transmission Control

Session Data Flow Control

telnet, np, SNMP, SMTPPresentation

Applications Transaction Services

NAU Services MgrFunc. Mgmt Data Srvc

TCP/IP OSI SNA

Layered Network Models

TCP/IP introduction

Network A Network B

pSeriesRouter

xSeriesRouter

xSeriesRouter

zSeriesGateway

pSeriesWorkstation Workstation Workstation

zSeries

xSeriesGateway

Interconnecting TCP/IP networks

Router

INTER-NETWORK

Network A Network B

Bridge

Gateway

Gateway

Router

Router

Internet addressing

IPv4

Host A

IP Address131.12.8.2

IP Address193.15.6.4

IP Address131.12.8.1

Host BGateway

Host C

IP Address193.15.6.3

Network131.12

Network193.15.6

IP address = x.x.x.x (32 bits)= <net-ID> <host addr>

Class A = <x> <x.x.x>Class B = <x.x> <x.x>Class C = <x.x.x> <x>

IP address = x.x.x.x (32 bits)= <net-ID> <host addr>

Class A = <x> <x.x.x>Class B = <x.x> <x.x>Class C = <x.x.x> <x> network ID host

address

193.15.6 3131.12 8.2

hostaddress

network ID

TCP/IP commands

• TCP/IP Commands can be entered– TSO ready prompt– ISPF Command Shell– Prefixing the command with TSO on any ISPF command

line. • NETSTAT • PING• TRACERTE• NSLOOKUP• TELNET• FTP

– z/OS UNIX shell prompt (prefix “o”=command)• onetstat

VTAM overview - the SNA environment

317x

Clustercontroller

Host processor

z/OSCICSVTAM

PCpSeries

AIX

iSeries

OS/400

zSerieszSeries

z/VM

WindowsWindows

Communicationcontroller (37xx)

Workstations

NCP

A pure VTAM subarea network

New York City

VTAM (SSCP) Subarea Configuration

Los Angeles Chicago

PU Type 2

LU LU

NCP subarea (13)PU Type 4

NCP subarea (12)PU Type 4

PU Type 2 PU Type 2

LU LU LU LU

NCP subarea (11)PU Type 4

VTAM subarea (3)SSCP (PU Type 5)

LU (CICSTS3)LU (IM S3)

VTAM subarea (1)SSCP (PU Type 5)

LU (CICSTS1)LU (IM S1)

VTAM subarea (2)SSCP (PU Type 5)

LU (CICSTS2)LU (IM S2)

PU Type 2

LU

LU

APPN topology

New York City

VTAM (CP) APPN Configuration

Los Angeles ChicagoPC PC

PC PC PC PC

router

VTAM APPNCP (PU Type 5)LU (CICSTS3)

LU (IM S3)

VTAM APPNCP (PU Type 5)LU (CICSTS1)

LU (IM S1)

VTAM APPNCP (PU Type 5)LU (CICSTS2)

LU (IM S2)

Internetsegment

PC

PC

internetsegment

router

Internetsegment

router

Internet and /orintranet

OSAHPR/IP

OSAHPR/IP

OSAHPR/IP

Common VTAM commands

• D NET,VTAMOPTS Displays VTAM startup options.• D NET,CSM[,OWNERID=ALL] Displays communication storage

usage.• D NET,APPLS Displays status of defined applications (ACBs).• D NET,MAJNODES Displays status of VTAM activated ATCCONxx

members.• D NET,TOPO,LIST=SUMMARY Displays APPN topology

information.• D NET,CPCP Displays status of APPN CP-CP sessions.• D NET,SESSIONS Displays status of subarea SSCP-SSCP

sessions.• D NET,CDRMS Displays status of subarea cross domain resource

managers.• D NET,EXIT Displays status of VTAM exit points.

Summary

• In this chapter, you have learned:– An overview of the communication network

model layers– Software components of the z/OS

Communications Server product– The difference between a VTAM subarea and

APPN network topology– How the IP network can be used to transport

data between SNA applications.– Commonly used TCP/IP and VTAM commands

Backup slides

Instructor slides with additional material

SDLC / CICS