Managing Serviceguard Eighteenth Edition, September 2010

What is VLAN?
Virtual LAN (or VLAN) is a technology that allows logical grouping of network nodes,
regardless of their physical locations.
VLAN can be used to divide a physical LAN into multiple logical LAN segments or
broadcast domains, helping to reduce broadcast traffic, increase network performance
and security, and improve manageability.
Multiple VLAN interfaces, each with its own IP address, can be configured from a
physical LAN interface; these VLAN interfaces appear to applications as ordinary
network interfaces (NICs). See Using HP-UX VLAN for more information on configuring
VLAN interfaces.
Support for HP-UX VLAN
VLAN interfaces can be used as heartbeat as well as data networks in the cluster. The
Network Manager monitors the health of VLAN interfaces configured in the cluster,
and performs local and remote failover of VLAN interfaces when failure is detected.
Failure of a VLAN interface is typically the result of the failure of the underlying
physical NIC port or aggregated (APA) ports.
Configuration Restrictions
HP-UX allows up to 1024 VLANs to be created from a physical NIC port. A large pool
of system resources is required to accommodate such a configuration; Serviceguard
could suffer performance degradation if many network interfaces are configured in
each cluster node. To prevent this and other problems, Serviceguard imposes the
following restrictions:
• A maximum of 30 network interfaces per node is supported. The interfaces can be
physical NIC ports, VLAN interfaces, APA aggregates, or any combination of
these.
• Local failover of VLANs must be onto the same link types. For example, you must
fail over from VLAN-over-Ethernet to VLAN-over-Ethernet.
• The primary and standby VLANs must have same VLAN ID (or tag ID).
• VLAN configurations are only supported on HP-UX 11i releases.
• Only port-based and IP-subnet-based VLANs are supported. Protocol-based VLAN
is not supported because Serviceguard does not support any transport protocols
other than TCP/IP.
• Each VLAN interface must be assigned an IP address in a unique subnet, unless
it is a standby for a primary VLAN interface.
• Failover from physical LAN interfaces to VLAN interfaces or vice versa is not
supported because of restrictions in VLAN software.
• Using VLAN in a Wide Area Network cluster is not supported.
• If CVM disk groups are used, you must not configure the Serviceguard heartbeat
over VLAN interfaces.
How the Network Manager Works 105