Discussion of CS/390 Definitions

This section contains additional information about the CS/390 definitions and their dependencies.

C.5.1 PORTNAME Operand

The portname gives an OSA-Express Gigabit Ethernet port a name. This name must be the same in every Communications Server/390 if running on multiple LPARs. This name is set to the OSA-Express Gigabit Ethernet from the first TCP/IP stack which activates the device. Once set, all following TCP/IP stacks must use the same portname. The portname is reset only when the CHPID to each LPAR is configured offline. The same portname can be set to different OSA-Express adapter on the same processor but TCP/IP does not support it within the same stack. We recommend that you use a unique portname for each OSA-Express.

The portname defined in a TRLE in VTAM is the same as the device name in the DEVICE statement of TCP/IP.

C.5.2 OSANAME Operand

The osaname is used to define an OS/390 image in the OSA-Express. The osaname is the same name as the TRLE defined in VTAM. Using this name the OSA-Express is able to distinguish the OS/390 image across multiple LPARs. Within a single OSA-Express the osaname must be unique.

HOME internet_address link_name

Syntax of Communications Server/390 Definitions 123 C.5.3 Datapath Address

One device address, called the datapath address, is used for data transfer in both directions between OSA-Express and the Common Storage Manager (CSM) of CS/390. Every TCP/IP stack needs one datapath address to an OSA-Express, because it correlates the datapath address to an IP address.

The datapath address need not be the immediate next address after the write address; it can be any address in the range of device addresses defined for the OSA-Express in HCD.

• If more than one OSA-Express is installed in the system, one datapath address to each OSA-Express adapter is needed. This means a separate TRLE definition in VTAM for every OSA-Express adapter must be defined.

• If TCP/IP stacks are running in separate LPARs (only one TCP/IP stack per partition), the same address can be shared between the partitions.

• If there is more than one TCP/IP stack running in the same LPAR, each TCP/IP stack needs a separate datapath address to the same

OSA-Express adapter. In VTAM there is only one TRLE defined, but it contains multiple datapath addresses. There is one datapath address for every TCP/IP stack.

Figure 111 on page 119 shows an example where 3 TCP/IP stacks on the same S/390 share an OSA-Express Gigabit Ethernet.

During activation of the OSA-Express device in TCP/IP, VTAM assigns one datapath address to this TCP/IP stack. VTAM itself decides which datapath address is assigned to which TCP/IP stack. There is no way to predefine this assignment.

C.5.4 READ and WRITE Addresses

The read and write addresses are used only to control a QDIO device. There is no data traffic across these addresses.

C.5.5 What Is Needed When...

No LPAR, only one TCP/IP stack, only one OSA-GbE

• Only one TRLE (osaname) is needed, containing only one datapath address.

• TCP/IP must refer to the portname in the TRLE.

No LPAR, multiple TCP/IP stacks, only one OSA-GbE For example, three TCP/IP stacks:

• Only one TRLE (osaname) is needed containing three datapath addresses.

• Each TCP/IP stack must refer to the portname in the TRLE.

• VTAM assigns one datapath address to each TCP/IP stack.

No LPAR, only one TCP/IP stack, multiple OSA-GbE

• One TRLE (osaname) is needed for each OSA-GbE, containing only one datapath address.

• TCP/IP must refer to the portname(s) in each of the TRLEs.

No LPAR, multiple TCP/IP stacks sharing multiple OSA-GbE For example, three TCP/IP stacks and two OSA-GbE:

• One TRLE (osaname) for each OSA-GbE is needed, each containing three datapath addresses.

• Each TCP/IP stack has two DEVICE and LINK statements. Each DEVICE statement refers to the portname to one TRLE.

• VTAM assigns, from both TRLEs, one datapath address to each TCP/IP stack.

Multiple LPARs with CS/390 and only one TCP/IP stack per LPAR sharing only one OSA-GbE

• Only one TRLE (osaname) is needed in each LPAR, containing only one datapath address. The portname must be the same and the TRLE name must be unique across the LPARs.

• Each TCP/IP stack must refer to the same portname in the TRLE.

Multiple LPARs with CS/390 and multiple TCP/IP stacks per LPAR sharing only one OSA-GbE

For example, two TCP/IP stacks per LPAR:

• Only one TRLE (osaname) is needed in each LPAR containing two datapath addresses. The portname must be always the same and the TRLE name must be unique across the LPARs.

• Each TCP/IP stack must refer to the same portname in the TRLE.

• VTAM assigns one datapath address to each TCP/IP stack.

Multiple LPARs with CS/390 and only one TCP/IP stack per LPAR sharing multiple OSA-GbEs

For example, three OSA-GbEs:

• Three TRLEs (osanames) are needed in each LPAR containing only one datapath address. For each single OSA-Express Gigabit Ethernet the portname must be the same across LPARs, but it must be unique across the OSA-Express adapters. The TRLE name must be unique.

• Each TCP/IP stack has three DEVICE and LINK statements. Each DEVICE statement refers to the portname of one TRLE.

Syntax of Communications Server/390 Definitions 125 Multiple LPARs with CS/390 and multiple TCP/IP stacks per LPAR sharing multiple OSA-GbEs

For example, three OSA-GbEs and two TCP/IP stacks per LPAR:

• Three TRLEs (osanames) are needed in each LPAR containing two datapath addresses. For each single OSA-Express Gigabit Ethernet the portname must be the same across LPARs, but must be unique for each OSA-Express adapter. The TRLE name must always be unique.

• Each TCP/IP stack has three DEVICE and LINK statements. Each DEVICE statement refers to the portname of one TRLE.

• VTAM in each LPAR assigns one datapath address to each TCP/IP stack in the same LPAR.

© Copyright IBM Corp. 1999 127