Managing a serial link in an input/output system which indicates link status by continuous sequences of characters between data frames
First Claim
1. A link-level facility for sending and receiving data transfers over a link in an input/output system, said link-level facility comprising:
- continuous sequence generating means connected to said link for generating continuous sequences for transmission over said link from said link-level facility, said continuous sequence indicating the operating status of said link;
frame generating means connected to said link for generating frames for transmission over said link from said link-level facility;
synchronizing means connected to said continuous sequence generating means and said frame generating means for synchronizing the transmission of frames with the transmission of said continuous sequences such that said frames are intermediate successive ones of said continuous sequences;
receiving means connected to said link for receiving continuous sequences and frames transmitted over said link to said link-level facility; and
state machine means connected to said receiving means, said frame generating means and said continuous sequence generating means, said state machine means for controlling said frame generating means and said continuous sequence generating means, said state machine having a recognition means connected to said receiving means for recognizing continuous sequences received by said receiving means from said link for determining if said link has a frame-transmitting status or a non-frame-transmitting status, a first state means connected to said frame generating means for allowing transmission of frames from said frame generating means over said link when said recognition means determines that the last continuous sequence received by said receiving means indicates said link has a frame-transmitting status, anda second state means connected to said frame generator for preventing transmission of frames from said frame generating means over said link when said recognition means determines that the last continuous sequence received by said receiving means indicates said link has a non-frame-transmitting status.
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Accused Products
Abstract
A link-level facility for managing the transmission of frames and continuous sequences of control characters over a link. The link-level facility includes a state machine which has a first state for allowing transmission of a frame over the link where a link-level facility at the other end of the link indicates that the link has a frame-transmitting status, and a second state for preventing the transmission of frames over the link when the link-level facility at the other end of the link has indicated that the link has a non-frame-transmitting status. The link-level facilitates signal the status of the link by means of continuous sequences of special characters intermediate frames transmitted over the link such that synchronism is maintained. The first state includes an inactive state and a working state, and the second state includes a link-failure state, and connection-recovery state and an off-line state.
29 Citations
9 Claims
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1. A link-level facility for sending and receiving data transfers over a link in an input/output system, said link-level facility comprising:
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continuous sequence generating means connected to said link for generating continuous sequences for transmission over said link from said link-level facility, said continuous sequence indicating the operating status of said link; frame generating means connected to said link for generating frames for transmission over said link from said link-level facility; synchronizing means connected to said continuous sequence generating means and said frame generating means for synchronizing the transmission of frames with the transmission of said continuous sequences such that said frames are intermediate successive ones of said continuous sequences; receiving means connected to said link for receiving continuous sequences and frames transmitted over said link to said link-level facility; and state machine means connected to said receiving means, said frame generating means and said continuous sequence generating means, said state machine means for controlling said frame generating means and said continuous sequence generating means, said state machine having a recognition means connected to said receiving means for recognizing continuous sequences received by said receiving means from said link for determining if said link has a frame-transmitting status or a non-frame-transmitting status, a first state means connected to said frame generating means for allowing transmission of frames from said frame generating means over said link when said recognition means determines that the last continuous sequence received by said receiving means indicates said link has a frame-transmitting status, and a second state means connected to said frame generator for preventing transmission of frames from said frame generating means over said link when said recognition means determines that the last continuous sequence received by said receiving means indicates said link has a non-frame-transmitting status. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification