Chapter 3. Connectivity 127
More information about the FC standards can be obtained from the following Web sites:
3.6 Open Systems Adapter-2 channel
The Open Systems Adapter-2 (OSA-2) features were designed to provide direct, industry
standard, local area network and ATM network connectivity in a multi vendor networking
OSA-2 features were the first features to bring the strengths of the S/390 architecture to the
network environment, namely: security, availability, enterprise-wide access to data, and
systems management. The following OSA-2 features continue to be supported in
z/Architecture for z900 servers:
OSA-2 FDDI (feature code 5202)
OSA-2 Ethernet/Token Ring (ENTR, feature code 5201) for Token Ring only.
For z900 server, this feature is called the OSA-2 Token Ring feature, and can only be
configured as two 4/16 Mbps Token Ring ports.
As well as the OSA-2 Token Ring feature, other OSA-2 features for Fast Ethernet and ATM,
have been superseded by OSA-Express features; see “OSA-Express channel” on
z900 server OSA-2 features provide SNA/APPN/HPR and TCP/IP connectivity (see
Figure 3-27) for the following LAN and network types:
100 Mbps Fiber Distributed Data Interface (FDDI)
4/16 Mbps Token Ring (T/R)
The OSA-2 features have been implemented as a channel type on the z900 server, and are
defined (CHPID type OSA) using the Hardware Configuration Definition (HCD). Each feature
port appears to the application software as a channel-attached device.
Note: IBM Statement of Direction, effective October 2001
z900 will be the last family of servers to provide an FDDI feature.
Note: Effective October 2001:
OSA-2 Token Ring feature (feature code 5201) is superseded by the OSA-Express
Fast Ethernet feature (feature code 2366), and OSA-Express Token Ring feature
(feature code 2367), as required.
OSA-2 Token Ring feature (feature code 5201) is not carried forward on G5/G6
server to z900 server upgrades.
OSA-2 Token Ring feature (feature code 5201) is carried forward on z900 server to
z900 server upgrades only if the new configuration retains parallel channel and/or
OSA-2 FDDI features, and there are available slots in the Compatibility I/O cage(s).
128 IBM eServer zSeries 900 Technical Guide
Figure 3-27 OSA-2 connectivity
The z900 server OSA-2 FDDI and OSA-2 Token Ring features are supported by the Open
Systems Adapter Support Facility (OSA/SF) program product. OSA/SF allows you to
customize the OSA-2 features to run in different modes. This product delivers a simple means
to configure and manage OSA-2 and to download software updates (to the OSA-2 feature) for
A default configuration is loaded in the OSA-2 feature during manufacturing. OSA/SF is used
to change the manufacturing default configuration, if required.
In LPAR mode, OSA-2 ports can be shared by any or all logical partitions on the server
platform. This is called
. Port sharing support is customized in the configuration of
the OSA-2 features by using the OSA/SF program product.
Using OSA/SF, the OSA-2 FDDI and OSA-2 Token Ring features can be configured into
several modes, depending on your system and network requirements, as follows:
TCP/IP Passthru mode (non-shared port)
In this mode, an OSA-2 port is capable of transferring TCP/IP LAN traffic to and from just
one TCP/IP host or logical partition. This is the default mode of OSA-2 and does not
require configuration using OSA/SF.
TCP/IP Passthru mode (shared port)
In this mode, an OSA-2 port is capable of transferring TCP/IP LAN traffic to and from more
than one TCP/IP host within multiple logical partitions. The use of OSA/SF is required for
SNA mode (non-shared port)
In this mode, an OSA-2 port is capable of transferring SNA LAN traffic to and from just one
LPAR. The use of OSA/SF is required for this configuration.
SNA mode (shared port)
In this mode, an OSA-2 port is capable of transferring SNA LAN traffic to and from multiple
LPARs. The use of OSA/SF is required for this configuration.