Allied Telesis AT-2973T/4, AT-2973SX manual Wake on LAN WOL Feature

Chapter 1: Introducing the AT-2973SX, AT-2973T, and AT-2973T/4 Adapters

Internet Small

Computer

Systems Interface

(iSCSI)

Power

Management

Wake on LAN (WOL) Feature

adapter, the TCP/IP processing can be moved to hardware, freeing the CPU for more important tasks such as application processing.

The Broadcom NetXtreme II adapter's TOE functionality allows simultaneous operation of up to 1024 fully offloaded TCP connections for 1-Gbps network adapters. The TOE support on the adapter significantly reduces the host CPU utilization while preserving the implementation of the operating system stack.

The IETF has standardized the Internet Small Computer Systems Interface (iSCSI). SCSI is a popular protocol that enables systems to communicate with storage devices, using block-level transfer (that is, address data stored on a storage device that is not a whole file). In addition, iSCSI maps the SCSI request and response application protocols and its standardized command set over TCP/IP networks.

As iSCSI utilizes TCP as its sole transport protocol, it greatly benefits from hardware acceleration of the TCP processing (that is, use of a TOE). However, iSCSI as a Layer 5 protocol has additional mechanisms beyond the TCP layer. iSCSI processing can also be offloaded, thereby reducing CPU utilization even further.

The Broadcom NetXtreme II adapter targets best-system performance, maintains system flexibility to changes, and supports current and future OS convergence and integration. Therefore, the adapter's iSCSI offload architecture is unique as evident by the split between hardware and host processing.

When the system is down and waiting for a wake-up signal, the adapter speed connection may be at 10 Mbps or 100 Mbps. However, it can return to 1000 Mbps when the system is up and running if it is connected to a 1000 Mbps capable switch. For this reason, connect systems that use the Wake on LAN (WOL) feature to a switch capable of both 1000 and 10/100 Mbps speeds.

The WOL feature sets the speed at which the network adapter connects to the network while the adapter is in Wake on LAN (WOL) mode which is enabled automatically. The default speed for WOL mode is 100 Mb. An adapter can negotiate speeds between 10 Mb and 100 Mb. You cannot configure this feature because it is enabled automatically.

Note

The WOL feature is supported on the AT-2973T and AT-2973T/4 adapters. It is not supported on the AT-2973SX adapter. For more information, see “Limitations” on page 66.

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