Browse Prior Art Database

CRC Remove and Check Control Parameter

IP.com Disclosure Number: IPCOM000116378D
Original Publication Date: 1995-Sep-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 76K

Publishing Venue

IBM

Related People

Gerardin, P: AUTHOR [+3]

Abstract

Disclosed is a system to control the CRC parameter in a transmission, involving hardware, picocode and microcode.

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

CRC Remove and Check Control Parameter

      Disclosed is a system to control the CRC parameter in a
transmission, involving hardware, picocode and microcode.

      Re-use of existing hardware leads to this implementation, but
it was anticipated to apply this method to a very simple hardware.

      The operator is not required to decide if CRC has to be removed
or checked.  These decisions are taken by this system.

      Assume the following network and HDLC transmission for a better
understanding:
  Server          Network Node       Network Node       Server
    or                                                    or
  Communic.       Hard. Scanner       Hard. Scanner      Communic.
  Controler       rcv     xmit        rcv     xmit       Controler
  Figure 1.  NETWORK

The possibilities provided by hardware Scanner are summarized in the
Table 1.
        Receive                 Transmit
    Check     Remove         Add       Check
  always     yes / no        no        yes
  checked                    yes        no
                             no         no
  (1)                        yes        yes (2)
  TABLE 1.  HARDWARE SCANNER POSSIBILITIES
  1.  In Receive, it is not possible to request a "non-checking";
  2.  In Transmit, the combination " Add=YES and Check=YES " is
always
       taken as " Add=YES and Check=NO " directly by the hardware,
i.e.,
       check will be ignored
                D I E D R E
       Receive               Transmit
       DATA   CRC            DATA   CRC
     REMOVE : YES / NO     ADD : YES / NO
     ALWAYS CHECK          CHECK : YES / NO
  Figure 2.  HARDWARE BEHAVIOUR REPRESENTATION

On another hand, depending of the protocol running on the line, the
CRC behaviours are described in Table 2.
      Receive                Transmit         Protocol
  Check     Remove        Add       Check
   yes        no           no        yes      FR /HDLC
   no         no           no        no       CBO          Port
 ...