Input/output channel interface which automatically deallocates failed subchannel and re-segments data block for transmitting over a reassigned subchannel

• US 5,793,983 A
• Filed: 01/22/1996
• Issued: 08/11/1998
• Est. Priority Date: 01/22/1996
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Menditto, Louis Frank, Nguyen, Tu Van, Holt, Robert Edward II, Albert, Mark, Stagg, Arthur James
• Primary Examiner(s): DINH, DUNG C
• Application Number:
  US08/589,276
• Time in Patent Office: 932 Days
• Field of Search: 395/200.56, 395/200.57, 395/200.58, 395/200.59, 395/200.8, 395/858, 395/182.02, 395/200.68, 395/200.69, 340/825.01, 340/825.03, 340/825.06, 340/827, 370/431, 370/463, 370/437, 370/216, 370/217, 370/218, 370/219, 370/220, 370/225, 370/228
• US Class Current: 709/239
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: H04L 25/14 Channel dividing arrangements , i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver

Abstract

A multi-path channel interface for computer input-output systems includes the ability to define and activate unbalanced groups of unidirectional communications sub-channels for a user application. Protocol independent exchange identifications permit not only unbalanced transmission groups but also allow user-controlled extensions for negotiating the values of transmission parameters at the time the transmission group is activated. When error correcting re-transmissions force the re-segmenting of data blocks, second level sub-segment indexing assure the proper order of delivery of the various segments and sub-segments. The exchange identifications include an identification of the user protocol being supported and thus permit interfacing with any user protocol.

Claims

1. An input and output communications subsystem at a first network node for transmitting and receiving data over a channel between the first network node and a second network node, the channel being partitioned into a plurality of subchannels of potentially different data capacities, said subsystem comprising

means for allocating the subchannels for transmission of data from the first node to the second node,

means for partitioning data for transmission to the second node into individual blocks for transmission over the allocated subchannels, the partitioning means further comprising means for establishing the sizes of the individual blocks to be equal to or less than the data capacity of the subchannel assigned for transmission of the block,

means for transmitting the individual blocks over the assigned subchannels,

means responsive to a failure of one of the sub-channels for providing a device unavailability signal to the subsystem,

means for automatically deallocating the failed subchannel in response to said device unavailability signal,

means responsive to the deallocating means for reassigning blocks already assigned to the failed subchannel to another one of the subchannels,

means for determining if the reassigned subchannel is of a lesser data capacity than the failed subchannel and, in response thereto, for segmenting blocks already partitioned for the failed subchannel into subsegments for transmission over the reassigned subchannel,

means responsive to a restoration of the failed subchannel for providing a device availability signal to the subsystem, and

means for automatically reallocating the failed subchannel in response to said device availability signal.

2. The input and output communications subsystem according to claim 1 further comprising

means for transmitting one or more identification exchange messages between the first node and the second node to prepare both ends to simultaneously reallocate the failed subchannel.

3. A method for execution by an input and output communications subsystem at a first network node for transmitting and receiving data over a channel between the first network node and a second network node, the channel being partitioned into a plurality of subchannels of potentially different data capacities, said method comprising the steps of

allocating the subchannels for transmission of data from the first node to the second node,

partitioning data for transmission to the second node into individual blocks for transmission over the allocated subchannels, the partitioning step further establishing the sizes of the individual blocks to be equal to or less than the data capacity of the subchannel assigned for transmission of the block,

transmitting the individual blocks over the assigned subchannels,

providing a device unavailability signal to the subsystem responsive to a failure of one of the sub-channels,

automatically deallocating the failed subchannel in response to said device unavailability signal,

reassigning blocks already assigned to the failed subchannel to another one of the subchannels,

determining if the reassigned subchannel is of a lesser data capacity than the failed subchannel and, in response thereto, segmenting blocks already partitioned for the failed subchannel into subsegments for transmission over the reassigned subchannel,

providing a device availability signal to the subsystem responsive to a restoration of the failed subchannel, and

automatically reallocating the failed subchannel in response to said device availability signal.

4. The method of claim 3 further comprising

transmitting one or more identification exchange messages between the first node and the second node to prepare both ends to simultaneously reallocate the failed subchannel.