Communications Server for z/OS V1R7 TCP/IP Implementation, Volume 1: Base Functions, Connectivity, and Routing

Chapter 2. The Resolver 39

Example 2-5 Ping command results

CS03 @ SC32:/u/cs03>ping router1

CS V1R7: Pinging host router1 (10.10.2.1)

Ping #1 response took 0.000 seconds.

It is also possible to verify where the resolver is looking by using the TRACE RESOLVER

parameter in the stack’s or application’s TCPIP.DATA data set. How this is done and the

contents of this trace will be explained in “Diagnosing the Resolver address space

environment” on page 43.

2.4.3 Implementing local settings in the Resolver environment

Once our Resolver address space is activated, all our global TCPIP.DATA statements will be

in place and cannot be overrided unless we change the setup data set and execute a

MODIFY command to use a new set of statements.

The TCP/IP stack or application is still able to use some local TCPIP.DATA statements to suit

its own requirements, such as the HOSTNAME and TCPIPJOBNAME. In this section we start

an FTP server (FTPDA), which establishes affinity with stack TCPIPA, and uses the

TCPIP.DATA data set (DATAA32) to create its own statements. We also create a user local

IPNODES data set for TSO user CS03, which will take precedence over the stack’s

IPNODES data set and over the default IPNODES data set pointed to by the Resolver

address space setup data set, as shown in Figure 2-17 on page 40.

40 Communications Server for z/OS V1R7 TCP/IP Implementation, Volume 1 - Base Functions, Connectivity, and Routing

Figure 2-17 Local Resolver configuration

Implementation tasks

To implement these local changes in our Resolver environment we did the following:

򐂰 Created a TCPIP.DATA data set named DATAA32 with the TCPIPA stack’s statements,

as shown in Example 2-6.

Example 2-6 TCPIP.DATA data set DATAA32

;OPTIONS DEBUG

TCPIPJOBNAME TCPIPA

HOSTNAME WTSC32A

DOMAINORIGIN ITSO.IBM.COM

DATASETPREFIX TCPIPA

MESSAGECASE MIXED

򐂰 Customized the TCPIPA stack procedure (RESOLVER_CONFIG) to point to DATAA32,

using the &sysclone variable to simplify our implementation to allow for a single procedure

to be used by any z/OS image in our sysplex environment, as shown in Example 2-7.

Example 2-7 TCPIPA procedure

//TCPIPA PROC PARMS='CTRACE(CTIEZB00),IDS=00',

// PROFILE=PROFA&SYSCLONE.,TCPDATA=DATAA&SYSCLONE

System Resolver

TCPIPA Stack

LPAR32

TCPIPA.TCPPARMS(GLOBAL):

Nameserver 9.12.6.7

Domain itso.ibm.com

Resolvevia UDP

...

TCPIPA.TCPPARMS(IPNODES):

9.12.6.7 OURDNS

10.10.1.230 WTSC30A

10.10.1.221 WTSC32A

10.10.1.241 WTSC31A...

TCPIPA.TCPPARMS(DEFAULT):

Hostname SC32

TCPIPJobname TCPIPA

//FTPDA PROC MODULE='FTPD',PARMS='',

//

TCPDATA=DATAA&SYSCLONE.,FTPDATA=FTPDA&SYSCLONE

//FTPD EXEC PGM=&MODULE,REGION=0M,TIME=NOLIMIT,

// PARM=('POSIX(ON) ALL31(ON)',

// 'ENVAR("_BPXK_SETIBMOPT_TRANSPORT=TCPIPA"',

// '"TX=EST")/&PARMS')

//CEEDUMP DD SYSOUT=*

//SYSFTPD DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&FTPDATA)

//SYSTCPD DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&TCPDATA)

//*

SETUP

GLOBALTCPIPDATA('TCPIPA.TCPPARMS(GLOBAL)')

DEFAULTTCPIPDATA('TCPIPA.TCPPARMS(DEFAULT)')

DEFAULTIPNODES (’TCPIPA.TCPPARMS(IPNODES)’)

COMMONSEARCH

FTPDA32 TSO user CS03

CS03.ETC.IPNODES:

9.12.4.221 tot177

10.10.1.230 tcpip30

10.10.1.241 tcpip31

10.10.2.1 router1

10.10.3.2 router2

TCPIPA.TCPPARMS(DATAA32):

Hostname wtsc32a

TCPIPJobname TCPIPA

DATASETPREFIX TCPIPA

Chapter 2. The Resolver 41

//TCPIPA EXEC PGM=EZBTCPIP,REGION=0M,TIME=1440,

// PARM=('&PARMS',

// 'ENVAR("RESOLVER_CONFIG=//''TCPIPA.TCPPARMS(&TCPDATA)''")')

//SYSPRINT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)

//ALGPRINT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)

//CFGPRINT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)

//SYSOUT DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)

//CEEDUMP DD SYSOUT=*,DCB=(RECFM=VB,LRECL=132,BLKSIZE=136)

//SYSERROR DD SYSOUT=*

//PROFILE DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&PROFILE.)

򐂰 Customized a FTPDA procedure to establish affinity with the TCPIPA stack and to use the

TCPIPDATA data set (DATAA32), as shown Example 2-8.

Example 2-8 FTPDA procedure

//FTPDA PROC MODULE='FTPD',PARMS='',

// TCPDATA=DATAA&SYSCLONE.,FTPDATA=FTPDA&SYSCLONE

//FTPD EXEC PGM=&MODULE,REGION=0M,TIME=NOLIMIT,

// PARM=('POSIX(ON) ALL31(ON)',

// 'ENVAR("_BPXK_SETIBMOPT_TRANSPORT=TCPIPA"',

// '"TX=EST")/&PARMS')

//CEEDUMP DD SYSOUT=*

//SYSFTPD DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&FTPDATA)

//SYSTCPD DD DISP=SHR,DSN=TCPIPA.TCPPARMS(&TCPDATA)

//*

򐂰 After establishing the affinity of FTPDA to work only with stack TCPIPA, we reserved ports

21 and 20 for the FTP server in PROFILE.TCPIP, as shown in Example 2-9.

Example 2-9 Reserving ports 20 and 21 to FTPDA

20 TCP omvs NOAUTOLOG ; FTP Server

21 TCP ftpda1 BIND 10.10.1.221; control port

򐂰 Created a TCPIPA.ETC.IPNODES data set to define the host names for stack TCPIPA,

which takes precedence over the default IPNODES data set when using this stack, as

shown in Example 2-10.

Example 2-10 TCPIPA.IPNODES data set

; Entries in the hosts file have the following format:

; Address HostName

; Address HostName1 HostName2 HostName3 ..... HostName35

; Address: is an IP address, it can be IPV4 or IPV6 address.

; Note: IPv4-mapped IPv6 address is not allowed.

; HostName: the length of the hostname is up to 128 characters,

; and each IP address can have up to 35 hostnames.

10.12.4.221 wscs01

10.10.1.230 tcpipa30

10.10.1.221 tcpipa32

10.10.1.241 tcpipa31

10.10.2.1 router1

10.10.3.2 router2

1::2 TESTIPV6ADDRESS1

1:2:3:4:5:6:7:8 TESTIPV6ADDRESS2

򐂰 Created a CS03.ETC.IPNODES data set to define host names to be used by TSOUSER

CS03 taking precedence over any other IPNODES data sets in our environment when

using this TSO user (see Example 2-11 on page 42).