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px12 Advanced Network Configuration Guide
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IEEE 802.3ad dynamic link aggregation: this mode dynamically bundles or channels NIC ports
together and shows them as a single link using the Link Aggregation Control Protocol (LACP).
It increases the total bandwidth for the link and provides fault tolerance in the event of switch
port, cable, or NIC failure. This mode requires that the switch fully supports the 802.3ad
standard and be configured before the bond is created.
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Switch failover: this mode provides fault tolerance across switches. A NIC connected to one
switch will automatically failover to a standby NIC connected to a different switch in the event
of a switch, switch port, cable, or NIC failure. No switch configuration is required. It works with
any switch, but not on hubs.
The px12 supports three modes: NIC failover, adaptive load balancing (ALB), and IEEE 802.3ad link
aggregation. To use the 802.3ad mode, the switch(es) that the px12 device is connected to must
also support the 802.3ad protocol. Configuration of a switch normally requires the service of a
network administrator. The other two modes do not require any switch-level configuration and are
therefore much simpler to implement.
JUMBO FRAME CONFIGURATION
A standard Ethernet frame size is 1518 bytes, containing 1500 bytes of payload (MTU). Each frame
requires that the network hardware and software process it. So if the frame size is increased, the
same amount of data can be transferred with fewer frames, thus reducing CPU utilization and
increasing network throughput due to reduction of network overhead. An Ethernet frame with more
than 1500 bytes of payload is called a Jumbo Frame. Conventionally, Jumbo Frames can carry up
to 9000 bytes of payload.
Most gigabit Ethernet switches and gigabit NICs support Jumbo Frames, but all Fast Ethernet
switches and Fast Ethernet NICs do not support Jumbo Frames. Normally, IP networks require that
all hosts in a subnet have an identical MTU. Therefore, when using Jumbo Frames, the best
practice is to enable Jumbo Frames on all network interfaces connected to the same subnet. To
reduce interoperability issues, NICs capable of Jumbo Frames require explicit configuration to
enable Jumbo Frame.
The px12 supports Jumbo Frames of sizes 4000 and 9000 bytes. Jumbo Frames can be configured
on individual interfaces and bonded interfaces.
OTHER I/O HIGH AVAILABILITY OPTIONS
All services on the px12 can take advantage of the advanced network capabilities described in this
paper to improve performance, security, and high availability. Additionally, the iSCSI service can
leverage the multipath I/O (MPIO) solution at the application layer to achieve enhanced high
availability and improved I/O performance.
The px12 network storage array is a certified iSCSI hardware-based RAID storage array with MPIO
support for windows Server 2003, windows Server 2008, and windows Server 2008 r2. Additionally,
