OSA VLAN

The IBM® Open Systems Adapter (OSA) technology provides support for IEEE standards 802.1p/q, which describes priority tagging and VLAN identifier tagging. Deploying VLAN IDs allows a physical LAN to be partitioned or subdivided into discrete virtual LANs. This support is provided by the z/OS® TCP/IP stack and the OSA

When you use VLAN IDs, the z/OS TCP/IP stack can have multiple connections to the same OSA feature. One connection is allowed for each unique combination of VLAN ID and IP version (IPv4 or IPv6). Each connection is defined by an INTERFACE statement and uses one channel unit address, or device number, for communication. For IPAQENET, the device number is assigned by VTAM from the DATAPATH parameter of the TRLE definition. For EQENET, the device number is assigned by the DEVNUM parameter on the INTERFACE statement. The configured device and the actual device used for EQENET can differ.
Tip: Each INTERFACE statement appears as a unique IP interface to the stack. When you configure multiple INTERFACE statements to the same OSA feature, each INTERFACE must also appear as a unique IP interface, for example, a unique IP address, VLAN, and subnet.
To configure one or more VLANs for a single OSA feature, take the following steps.
  • For an OSA-Express feature, in the TCP/IP profile configure:
    • An IPAQENET INTERFACE statement for each required IPv4 interface.
    • An IPAQENET6 INTERFACE statement for each required IPv6 interface.
  • For a Network Express feature, in the TCP/IP profile configure:
    • An EQENET INTERFACE statement for each required IPv4 interface
    • An EQENET6 INTERFACE statement for each required IPv6 interface.
VLANID
Configure a VLANID value on each IPv4 INTERFACE statement and each IPv6 INTERFACE statement on this stack for this OSA feature. Within each IP version, these VLANID values must be unique.
Restriction: The stack supports a maximum of 32 VLAN interfaces per IP version to the same OSA port.
VMAC
Configure the VMAC parameter on each of the INTERFACE statements with the default ROUTEALL attribute.
Requirement: VMAC is required when:
  • you configure multiple INTERFACE statements for the same OSA and IP version.
  • you configure one or more INTERFACE statements for Network Express.
    Requirement: The INTERFACE statement for the Network Express feature requires the VMAC parameter.
When you configure a VMAC you can specify the VMAC address or OSA can generate it.
Rule: If you specify a VMAC address, it must be unique for each INTERFACE statement. The VMAC address also must be unique on the external LAN.
Tip: It can become complicated to coordinate unique user defined VMAC addresses. An OSA generated VMAC address is guaranteed to be unique among all of the OSA features on the LAN. It is recommended to use an OSA generated VMAC address.
Subnet
Configure a unique subnet for each IPv4 interface for this OSA feature, by using the subnet mask specification on the IPADDR parameter on the INTERFACE statement.
Requirement: Subnet is required when:
  • The OSA feature is the OSA-Express feature and more than one INTERFACE statement is defined or the INTERFACE statement also defines SMCRIPADDR (SMC-Rv2).
  • The OSA feature is Network Express.
OMPROUTE
If you are using OMPROUTE and OMPROUTE is not configured to ignore this interface, ensure that the subnet mask value that you configure on the INTERFACE statement in the TCP/IP profile matches the subnet mask that is used by OMPROUTE for this interface. The subnet mask that OMPROUTE uses is the subnet mask value that is defined on the corresponding OMPROUTE statement, OSPF_INTERFACE, RIP_INTERFACE, or INTERFACE, for this interface. If no OMPROUTE statement is specified for this interface, the subnet mask that OMPROUTE uses is the class mask for the interface IP address.
Device selection
Each INTERFACE statement requires a unique device for the associated OSA CHPID. Ensure that a device is (or enough devices are) available. Note. Available means, defined in HCD and online to z/OS. The device used for each interface must be associated with the correct adapter (CHPID). The specific device number used for each interface is arbitrary. Devices are dynamically assigned during INTERFACE activation, typically using the next available device. OSA devices are defined as follows:
  • For OSA-Express: DATAPATH parameter in the TRLE definition for each IPv4 interface and for each IPv6 interface for this OSA-Express feature.
  • For Network Express: DEVNUM parameter on the EQENET and EQENET6 INTERFACE statements.
    Note: The DEVNUM parameter is used by Communications Server to find the available devices for a given OSH CHPID. The next available device is used to activate the interface.
    Rule: If you configure multiple INTERFACE statements for the same Network Express feature (CHPID), then all INTERFACE statements must specify the same device number on DEVNUM.
Fixed storage
Ensure that you understand the fixed storage requirements for this configuration; each interface requires its own device, and each device requires fixed storage for read processing. For more information see:
Restriction:
  • The stack supports a maximum of 32 VLAN interfaces per IP version to the same OSA port. When configuring multiple interfaces, System Fixed storage usage must be taken into consideration.