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

Chapter 4. Connectivity 119

eliminated, along with the cost, complexity, and maintenance of the networking components

that interconnect them.

Consolidated servers that have to access corporate data residing on the System z9 or

zSeries server can do so at memory speeds, bypassing all the network overhead and delays.

HiperSockets can be customized to accommodate varying traffic sizes. (In contrast, LANs,

like Ethernet and Token Ring, have a maximum frame size predefined by their architecture.)

With HiperSockets, a maximum frame size can be defined according to the traffic

characteristics transported for each of the four possible HiperSockets.

Since there is no server-to-server traffic outside the System z9 or zSeries server, a much

higher level of network availability, security, simplicity, performance, and cost effectiveness is

achieved as compared with servers communicating across a LAN. For example:

򐂰 Since HiperSockets has no external components. It provides a very secure connection.

For security purposes, servers can be connected to different HiperSockets. All security

features, like firewall filtering, are available for HiperSockets interfaces as they are with

other TCP/IP network interfaces.

򐂰 HiperSockets looks like any other TCP/IP interface; therefore, it is transparent to

applications and supported operating systems.

򐂰 HiperSockets can also improve TCP/IP communications within a sysplex environment

when the DYNAMICXCF is used (for example, in cases where Sysplex Distributor uses

HiperSockets within the same CEC to transfer IP packets to the target systems).

Considerations

The z/OS Communications Server does not support VLANs in conjunction with HiperSockets.

Therefore, if you have a requirement to restrict data traffic flow among the certain LPARs in

the server, we recommend that you connect those LPARs to a separate HiperSockets.

4.3.3 Dynamic XCF connectivity

The last connectivity scenario we are going to add to our test environment is to connect all

images within the same Sysplex environment through a dynamic XCF connection, created by

the DYNAMICXCF definition in the TCP/IP profile.

Once defined, DYNAMICXCF will provide connectivity between stacks under the same LPAR

by using the IUTSAMEH device (SAMEHOST) and between LPARs through HiperSockets

using a IUTiQDIO device. To connect other z/OS images or other servers, an XCF coupling

facility link is created.

In our test scenario we use DYNAMICXCF through HiperSockets with IQD CHPID F7. So by

defining the DYNAMICXCF statement, we will create the XCF subnetwork through

HiperSockets, as seen in Figure 4-10 on page 120.

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

Figure 4-10 XCF implementation scenario with HiperSockets

Dependencies

The dependencies are:

򐂰 All z/OS hosts must belong to the same sysplex.

򐂰 VTAM must have XCF communications enabled by specifying XCFINIT=YES or

XCFINIT=DEFINE as a startup parameter or by activating the VTAM XCF local SNA major

node, ISTLSXCF. For details about configuration, refer to z/OS V1R7.0 Communications

Server SNA Network Implementation, SC31-8777-05.

򐂰 DYNAMICXCF must be specified in the TCP/IP profile of each stack.

򐂰 The IQD CHPID being used for the DYNAMICXCF device cannot be the user-defined

HiperSockets device (IQD CHPID). To avoid this, a VTAM start options, IQDCHPID, can

be used to identify which IQD CHPID will be used by DYNAMICXCF.

Advantages

You have a choice of defining the XCF connectivity to other TCP/IP stacks individually or

using the dynamic XCF definition facility. Dynamic XCF significantly reduces the number of

definitions that you need to create whenever a new system joins the sysplex or when you

need to start up a new TCP/IP stack. These changes become more numerous as the number

of stacks and systems in the sysplex grows. This could lead to configuration errors. With

dynamic XCF you do not need to change the definitions of the existing stacks in order to

accommodate the new stack.

OSA IP addresses

2080: 10.10.2.232

20A0: 10.10.3.233

20C0: 10.10.2.234

20E0: 10.10.3.235

HiperSockets IP addresses

CHPID F4: 10.10.4.234

CHPID F5: 10.10.4.235

CHPID F6: 10.10.5.236

DYNAMICXF

HiperSockets IP address

CHPID F7 10.20.10.100

z/OS LPAR: A23

Static VIPA: 10.10.1.230

OSA IP addresses

2080: 10.10.2.242

20A0: 10.10.3.243

20C0: 10.10.2.244

20E0: 10.10.3.245

HiperSockets IP addresses

CHPID F4: 10.10.4.244

CHPID F5: 10.10.4.245

CHPID F6: 10.10.5.246

DYNAMICXF

HiperSockets IP address

CHPID F7 10.20.10.101

z/OS LPAR: A24

Static VIPA: 10.10.1.241

OSA IP addresses

2080: 10.10.2.222

20A0: 10.10.3.223

20C0: 10.10.2.224

20E0: 10.10.3.225

HiperSockets IP addresses

CHPID F4: 10.10.4.224

CHPID F5: 10.10.4.225

CHPID F6: 10.10.5.226

DYNAMICXF

HiperSockets IP address

CHPID F7 10.20.10.102

z/OS LPAR: A22

Static VIPA: 10.10.1.221

CHPID: F4

Devices: E800-E81F

CHPID: F5

Devices: E900-E91F

CHPID: F6

Devices: EA00-EA1F

CHPID: F7

IP Network

OSA-Express 1000BASE-T

HiperSockets

System z9

DYNAMICXCF

HiperSockets

CF38

CF LPAR:

A2E

CHPID 04

20C0-20CF

CHPID 05

20E0-20EF

CHPID 02

2080-208F

CHPID 03

20A0-20AF

Cisco

6509

Cisco

6509