Efficient timeout message management in IEEE 1394 bridged serial bus network

A method for reducing the transaction time to obtain a total timeout values for remote transactions between nodes of a source bus and a destination bus, said method comprising the steps of:

• (a) providing a source bus and a destination bus in a serial path having an intermediate bus connected between the source bus and destination bus via bridges;
• (b) intercepting by a portal of said intermediate bus a TIMEOUT response message sent from an exit portal of the destination bus to a particular TIMEOUT requesting node on the source bus;
• (c) storing first remote timeout values from the TIMEOUT response message intercepted in step (b) in a storage area of said portal of said intermediate bus and forwarding the TIMEOUT response message intercepted in step (b) to said particular TIMEOUT requesting node on the source bus;
• (d) intercepting by said portal of said intermediate bus said intermediate bus a subsequent TIMEOUT request message from a subsequent requesting node of said plurality of nodes of said source bus to a node of said plurality of nodes of said destination bus;
• (e) said portal of the intermediate bus calculating a remote timeout values from the source bus to the destination bus by adding the first timeout values stored in step (c) to second remote timeout values between the source bus and the intermediate bus except for a max_remote payload value;
• (f) synthesizing a TIMEOUT response message by said portal of said intermediate bus, said synthesized TIMEOUT RESPONSE including the total timeout values calculated in step (e);
• and
• (g) forwarding said synthesized TIMEOUT response message to said subsequent requesting node of said source bus in step (d) that initiated the TIMEOUT request message.

A serial bus bridged network having a reduced-response timeout management system, comprising

• a source bus having a first portal with a register table;
• at least one intermediate bus having a bridge comprising
• a second portal including a register table;
• a destination bus having an exit portal;
• a plurality of bus bridges which serially connects said source bus, said at least one intermediate bus and said destination bus;
• said first portal of the source bus including means for receiving a TIMEOUT request from a node attached thereto;
• said exit portal of said destination bus including means for receiving a TIMEOUT request message and for sending a TIMEOUT response message having timeout values included therein;
• intercepting and storing means for intercepting by the bridge portal of said intermediate bus the TIMEOUT response message sent by the exit portal of the destination bus, and for storing timeout values of the TIMEOUT response message from the exit portal of said destination bus in the register table of the bridge portal of the intermediate bus;
• means for intercepting and synthesizing, in which said second portal of said intermediate bus intercepts a TIMEOUT request from a node on said source bus, and when an ID of the destination bus in the TIMEOUT request matches an ID of said destination bus having its timeout values stored in the register table of the second portal of the intermediate bus, the second portal synthesizing a TIMEOUT response message comprising a total timeout values by adding the timeout values between said destination bus and said intermediate bus and the timeout values between said source bus and said intermediate bus, except for max_remote payload values, which is a smaller of the intercepted TIMEOUT request message and corresponding table entry,
• means for transmitting the synthesized TIMEOUT response message having the total timeout values sent to the requesting node on said source bus.