In-band device configuration protocol for atm transmission convergence devices

Abstract

Line card control in an ATM or other packet-based switch is provided using an in-band device configuration in which control messages from a control processor of the switch are transmitted in one or more cells to a transmission convergence device in a line card. The transmission convergence device filters a stream of cells received in the line card in order to identify cells including control messages directed to the line card. The transmission convergence device then executes one or more commands associated with a given control message. Each control message may be transmitted in a single cell including a header and a payload. A message trailer portion of the payload may include device-specific data which specifies an interpretation of the payload structure. For example, the payload may include a series of commands, each including a read or write opcode, an address, and a data field. Alternatively, the device-specific data may indicate that the payload includes a single read command, with a longer address and a larger data field. The message trailer may also include a CRC field which is compared with a CRC computed for the payload to determine whether the control message should be accepted or rejected, and a pass-through data field which is returned unmodified from the line card as part of an acknowledgment of receipt and execution of the control message.