Browse Prior Art Database

Method and Apparatus for Efficient Multiprotocol Packet Handling in a Communication Controller

IP.com Disclosure Number: IPCOM000114249D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 4 page(s) / 126K

Publishing Venue

IBM

Related People

Ashton, JL: AUTHOR [+4]

Abstract

Disclosed is a method for preprocessing multiprotocol packets and a description of an adapter (the apparatus) that allows the method to be implemented in a communication controller.

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

Method and Apparatus for Efficient Multiprotocol Packet Handling
in a Communication Controller

      Disclosed is a method for preprocessing multiprotocol packets
and a description of an adapter (the apparatus) that allows the
method to be implemented in a communication controller.

      Disclosed is a method for efficient preprocessing by an adapter
of multiprotocol packets received into a communication controller
from a packet switch network.  For example, when the traffic received
over a single line includes International Business Machines (IBM)
System Network Architecture (SNA) Subarea and Peripheral traffic
types, as well as Internet Protocol (IP) packets.  The American
National Standards Institute Incorporated (ANSI) standards T1.617 and
T1.618 define the packet network frame formats.  The SNA and IP
protocol formats are defined by IBM and the Internet Engineering Task
Force (IETF), and are well known in the communications industry.

      Following is a description of a dynamic method of controlling
the type of processing in the serial line adapters by a program
located in the main processor.  Placing a preprocessing facility in
the serial line adapters can greatly improve the controller packet
processing capabilities.  It is difficult and complex to determine
the best function placement for packet processing and routing of
multiple protocols in a controller.  The method disclosed, allows
changes to a table to control the preprocessing performed by a line
adapter.  The table can be changed without requiring hardware changes
to the adapter apparatus, and allows a much closer approach to the
ideal function placement for processing packets of each protocol
type.

      The communications controller typically contains one or more
Serial Communications Adapters (SCAs) that form a data interface to a
data link into a packet switch network.  The communications
controller also includes a Central Control Unit (CCU) for controlling
the operation of the SCAs.  Data received from the packet switch
network over the data link is placed in the main memory by the SCA
for inspection by the Network Control Program (NCP) in the CCU.  The
NCP must inspect the packet headers to determine what processing is
needed and which route to use for the packet to reach its final
destination.  In response to a request from the NCP, the SCA will use
a table located in main storage to control the placement of the
packets received, into buffer lists in main storage.  The correct
placement of data from the received packets in the main storage
buffer lists, can greatly increase the number of packets per second
the CCU and NCP can process.

      The novelty consists of the use of a complex control table to
identify the best location for the header and the data from a packet.
And using information from the control table to provide a search
string and index i...