IBM Netfinity, User Manual

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Netfinity® Gigabit Ethernet Adapter User’s guide
Key protocols and interfaces
The Netfinity Gigabit Ethernet Adapter is compatible with existing Ethernet equipment
assuming standard Ethernet minimum and maximum frame size (64 to 1518 bytes), frame
format, and compliance with the following standards and protocols:
• Gigabit Ethernet (IEEE 802.3-1999)
• Logical Link Control (IEEE 802.2)
• Flow Control (IEEE 802.3x)
Jumbo Frames support
When sending Ethernet traffic at Gigabit speeds, considerable bandwidth is consumed by
the overhead of handling a multitude of standard 1,500 byte packets. The Netfinity Gigabit
Ethernet Adapter and Alteon WebSystems switches support Ethernet frames of up to 9,000
bytes. Host CPU utilization is significantly reduced and network throughput is enhanced
when enabling Jumbo Frames between servers that have IBM PCI adapters.
For user datagram protocol (UDP) traffic, an IBM Netfinity Gigabit Ethernet Adapter can
support standard Ethernet frames and Jumbo Frames at the same time. When attached to
an Alteon WebSystems switch, Jumbo Frames are sent only between servers that have
Netfinity Gigabit Ethernet Adapters. When attached to a standard Ethernet device, a
Jumbo Frames-enabled server might send UDP data in Jumbo Frames, but when the data
reaches the switch, the switch automatically fragments the data into standard Ethernet
frames when sending to all other standard Ethernet devices.
For non-UDP traffic, both servers must support Jumbo Frames.
VLANs support
Virtual local area networks (VLANs) are commonly used to divide groups of network
users into manageable broadcast domains, to create logical segmentation of workgroups,
and to enforce security policies among logical segments.
Each Netfinity Gigabit Ethernet Adapter supports up to 64 VLANs, depending on the
amount of memory available in your computer. With multiple VLANs on an adapter, a
server with a single adapter can have a logical presence on multiple IP subnets. For details
about planning networks with VLANs, refer to your Alteon WebSystems switch software
manual.
Adapter teaming
Teaming provides redundant adapter operation in the event that a network connection
fails. When multiple Netfinity Gigabit Ethernet Adapters are installed in the same server,
they can be paired into teams. Up to two teams, each with two adapters, can be configured
on the server.
If traffic is not detected on the primary adapter connection in a team because the adapter,
cable, switch port, or switch (where the teamed adapters are attached to separate switches)
fails, the secondary team member becomes active, taking the MAC and IP address
originally assigned to the primary adapter. Sessions are usually maintained, causing no
impact to the user.