Browse Prior Art Database

Direct Attached Local Area Network Adapter with Power Conservation Capabilities

IP.com Disclosure Number: IPCOM000118977D
Original Publication Date: 1997-Oct-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 86K

Publishing Venue

IBM

Related People

Christensen, KJ: AUTHOR [+3]

Abstract

When a Local Area Network (LAN) attached workstation goes into low-power "sleep mode", existing LAN adapters are powered-off and disconnected - incoming messages from the LAN cannot be received. Disclosed is a low-power LAN adapter that wakes-up for an incoming message. A wake-up signalling sequence based on non-data symbols is used to indicate an incoming message and allow the LAN adapter and workstation time to wake-up for normal operation. A low-power sleep-mode LAN adapter can power-off all of its circuitry except its receiver.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Direct Attached Local Area Network Adapter with Power Conservation
Capabilities

      When a Local Area Network (LAN) attached workstation goes into
low-power "sleep mode", existing LAN adapters are powered-off and
disconnected - incoming messages from the LAN cannot be received.
Disclosed is a low-power LAN adapter that wakes-up for an incoming
message.  A wake-up signalling sequence based on non-data symbols is
used to indicate an incoming message and allow the LAN adapter  and
workstation time to wake-up for normal operation.  A low-power
sleep-mode LAN adapter can power-off all of its circuitry except its
receiver.

      Fig. 1 shows direct attached LAN adapters and a
concentrator.  Upon notification from a concentrator port, a
sleep-mode LAN adapter wakes-up all its functions and first then
turns-on its transmitter.  If the concentrator port does not receive
a signal after  a period of time following wake-up notification, it
is assumed that the  LAN adapter is physically disconnected.

      Two states are defined for the LAN adapter - SLEEP and
AWAKE.  In the SLEEP state, all LAN adapter circuitry may be
powered-down except the receiver.  The receiver is an extremely
low-power function in a LAN adapter.  The workstation may also be in
a powered-down state.  In the AWAKE state, all LAN adapter circuitry
is powered-up and the transmitter is continuously transmitting
symbols - the LAN adapter and workstation are ready to receive
frames.  Transition from AWAKE to SLEEP is typically initiated by the
workstation.  Transition from SLEEP to AWAKE occurs when a WAKE-UP
non-data symbol is received and after the workstation and LAN adapter
are fully powered-up. Non-data  symbols include delimiters for the
start and end of fram...