Browse Prior Art Database

Auxiliary Lookup Register for Switches in Multi-Ring Networks

IP.com Disclosure Number: IPCOM000111141D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 98K

Publishing Venue

IBM

Related People

Chen, W: AUTHOR [+2]

Abstract

A means of splitting the routing decision logic in a switch port of a switch for a multi-ring interconnection network is described. One logic component determines whether a packet should be stripped from the ring and routed to another switch port (ring). A separate logic component determines which switch port (ring) a stripped packet should be routed.

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

Auxiliary Lookup Register for Switches in Multi-Ring Networks

      A means of splitting the routing decision logic in a switch
port of a switch for a multi-ring interconnection network is
described.  One logic component determines whether a packet should be
stripped from the ring and routed to another switch port (ring).  A
separate logic component determines which switch port (ring) a
stripped packet should be routed.

      A switch in the interconnection network for a multi-ring system
consists of a component with multiple ports.  Each of the ports
participates as a port on a distinct ring.  The internal structure of
the switch is such that a packet traveling on a ring attached to port
j of the switch can be taken off that ring by switch port j and
routed to another switch port k, where port k transmits the packet
onto a different ring.  With such a switch and an appropriate method
for routing packets to distant nodes, a multiprocessor system can be
constructed from multiple rings interconnected by switches.

      In a conventional switch port design, when a packet is
received, the switch port makes a routing decision: "Which port of
this switch is this packet destined?"  In a general topology of N
possible destinations, this decision is made by taking the routing
tag (e.g., the destination node for the packet) from the header of
the packet and using it as an index into a N-entry table.  The value
returned from this lookup table is the switch port to which the
packet should be routed.  If the destination switch port number
equals the switch port number of the port that just received the
packet, then the packet is transmitted back onto the ring from which
it came.

      One port from such a switch is shown in the figure.  For
example (refer to figure), an incoming packet on the INPUT PATH
passes through a demultiplexor that either routes the packet to the
BUFFER INSERTION QUEUE or the INPUT QUEUE.  Packets to be routed to
some other switch port are routed to the INPUT QUEUE.  Otherwise, the
packet is routed into the BUFFER INSERTION QUEUE.  The details of
this routing decision are covered later.  As a packet reaches the
head of the INPUT QUEUE, it is routed through another demultiplexor
which sends it to the appropriate switch port.  The packet is then
routed to the OUTPUT QUEUE of the other switch port and eventually
transmitted from the switch.

      The invention of this disclosure is based on the...