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Hybrid Switch Control Scheme for Fast Point-to-Point Multicast Hunt-Group Connection Setup

IP.com Disclosure Number: IPCOM000114251D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 6 page(s) / 261K

Publishing Venue

IBM

Related People

Cheng, TD: AUTHOR [+4]

Abstract

Disclosed is a hybrid distributed/centralized switch control scheme for achieving fast connection setup times that are usually enjoyed by distributed control schemes, while allowing the convenience of implementing multicast/hunt-group connections previously only available from centralized schemes.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 24% of the total text.

Hybrid Switch Control Scheme for Fast Point-to-Point Multicast Hunt-Group
Connection Setup

      Disclosed is a hybrid distributed/centralized switch control
scheme for achieving fast connection setup times that are usually
enjoyed by distributed control schemes, while allowing the
convenience of implementing multicast/hunt-group connections
previously only available from centralized schemes.

      Distributed control schemes for switching systems usually allow
more modular growth in system size and higher availability than
centralized control ones.  Furthermore, they reduce the processing
overhead and queuing delay usually associated with a centralized
control scheme.  However, it is much easier to implement multicast
and hunt-group connection setup, both of which are required by the
Fiber Channel Standard (FCS), in a centralized control scheme because
of the instant availability of the status information of the entire
system.  Therefore, it is more desirable to have a control scheme
which combines the benefits from both centralized and distributed
control schemes.

      In this invention, a hybrid distributed/centralized control
architecture and a connection request conflict resolution protocol
are described for a switching system incorporating crosspoint
switches.

      The essence of this scheme is that a Virtual-Centralized
Controller (VCC) is provided at each level of distributed processing.
This controller does not participate in point-to-point connection
setup since only the controllers of the source and destination ports
are involved.  However, up-to-date status of each port is
continuously acquired by the VCC through a status combining network.
Whenever a multicast or a hunt-group connection needs to be setup, it
is treated as a point-to-point connection and the connection request
is sent to the VCC just the same way as establishing a point-to-point
connection.  Because of the availability of the system status at the
VCC, much fewer transactions are required to establish a multicast or
hunt-group connection which usually involves more than two ports.  In
a multi-level hierarchical switching structure, a VCC can also serve
as a smart bridge between the lower-level and higher-level VCC's to
filter interlevel connection request or accept messages while
maintaining a homogeneous addressing scheme for intra-cluster as well
as inter-cluster connections.

      A major difference of this architecture, as compared to a
centralized control scheme, is that the VCC does not participate in
point-to-point connection setup, and thus the faster connection setup
time enjoyed by a distributed processing scheme is not compromised.

      Hybrid Centralized/Distributed Control Network Architecture - A
large switching system consisting of several smaller switching
fabrics is shown in Fig. 1.

      Both horizontal partitioning of the switch fabric and I/O port
adapter grouping have been assumed.  As shown in this...