Specifications

Chapter 3. Virtualization 139
A single SEA setup can have up to 16 Virtual Ethernet trunk adapters and each virtual
Ethernet trunk adapter can support up to 20 VLAN networks. Therefore, a possibility is for a
single physical Ethernet to be shared between 320 internal VLAN networks. The number of
shared Ethernet adapters that can be set up in a Virtual I/O Server partition is limited only by
the resource availability, because there are no configuration limits.
Unicast, broadcast, and multicast are supported, so protocols that rely on broadcast or
multicast, such as Address Resolution Protocol (ARP), Dynamic Host Configuration
Protocol (DHCP), Boot Protocol (BOOTP), and Neighbor Discovery Protocol (NDP), can
work on an SEA.
For a more detailed discussion about virtual networking, see:
http://www.ibm.com/servers/aix/whitepapers/aix_vn.pdf
Virtual SCSI
Virtual SCSI is used to refer to a virtualized implementation of the SCSI protocol. Virtual SCSI
is based on a client/server relationship. The Virtual I/O Server logical partition owns the
physical resources and acts as a server or, in SCSI terms, a target device. The client logical
partitions access the virtual SCSI backing storage devices provided by the Virtual I/O Server
as clients.
The virtual I/O adapters (virtual SCSI server adapter and a virtual SCSI client adapter) are
configured using a managed console or through the Integrated Virtualization Manager on
smaller systems. The virtual SCSI server (target) adapter is responsible for executing any
SCSI commands that it receives. It is owned by the Virtual I/O Server partition. The virtual
SCSI client adapter allows a client partition to access physical SCSI and SAN attached
devices and LUNs that are assigned to the client partition. The provisioning of virtual disk
resources is provided by the Virtual I/O Server.
Physical disks presented to the Virtual/O Server can be exported and assigned to a client
partition in a number of ways:
򐂰 The entire disk is presented to the client partition.
򐂰 The disk is divided into several logical volumes, which can be presented to a single client
or multiple clients.
򐂰 As of Virtual I/O Server 1.5, files can be created on these disks, and file-backed storage
devices can be created.
The logical volumes or files can be assigned to separate partitions. Therefore, virtual SCSI
enables sharing of adapters and disk devices.
Note: A Shared Ethernet Adapter does not need to have an IP address configured to be
able to perform the Ethernet bridging functionality. Configuring IP on the Virtual I/O Server
is convenient because the Virtual I/O Server can then be reached by TCP/IP, for example,
to perform dynamic LPAR operations or to enable remote login. This task can be done
either by configuring an IP address directly on the SEA device or on an additional virtual
Ethernet adapter in the Virtual I/O Server. This leaves the SEA without the IP address,
allowing for maintenance on the SEA without losing IP connectivity in case SEA failover
is configured.