z/VSE 5.1 Layer 2 support and connectivity options with zBX
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Before z/VSE 5.1 z/VSE only supported Layer 3 configurations. Layer 3 is the network layer (IP) of the TCP/IP protocol stack (Open Systems Interconnection - OSI model). With Layer 3 the TCP/IP stack uses IP packets that include IP addresses to determine source and destination. Layer 3 is supported by both z/VSE TCP/IP Stacks - TCP/IP for VSE/ESA (licensed from CSI) and IPv6/VSE (licensed from BSI).
Since z/VSE 5.1 Layer 2 - the data link layer of the OSI model - is supported in addition to Layer 3. In Layer 2 configurations the TCP/IP stack uses Ethernet frames that include MAC addresses to determine source and destination. Layer 2 is supported by the TCP/IP stack IPv6/VSE only.
The use of Layer 2 and Layer 3 is transparent to TCP/IP applications. Layer 3 is the default mode for z/VSE devices of type OSAX (OSA Express, HiperSockets).
IPv6/VSE V1.1 adds Layer 2 support for OSA Express devices (CHPID type OSD or OSX) when used in an IPv6 link. Layer 2 has to be specified explicitly in the IPv6/VSE configuration. You can now include a z/VM VSWITCH into your z/VSE IPv6 configuration.
When accessing the Intra-Ensemble Data Network (IEDN) through a z/VM VSWITCH connected to a zEnterprise Blade Center Extension (zBX) you can use IPv6 links in addition to IPv4 links.
zBX is a new infrastructure, that can be connected to the zEnterprise system, running POWER and System x compute elements. The zBX network connectivity options (including Layer 2 and Layer 3) are described in a new IBM Redpaper draft.
You may start with the z/VSE Planning book to read about z/VSE's connectivity options.