Browse Prior Art Database

Dynamic Bandwidth Allocation for Striping and Hunt Groups in a Switched Network

IP.com Disclosure Number: IPCOM000104837D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 115K

Publishing Venue

IBM

Related People

Cheng, T: AUTHOR [+3]

Abstract

Disclosed is a dynamic bandwidth allocation scheme for the efficient utilization of switched I/O networks, in which the switch can distribute and control the accessing of the network links. The scheme enables striping and hunt group operations to share the same hardware facilities. It applies to networks that have multiple links between each network node and the switch. Some of the disclosed principles are also applicable to cascaded switches.

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This is the abbreviated version, containing approximately 47% of the total text.

Dynamic Bandwidth Allocation for Striping and Hunt Groups in a Switched Network

      Disclosed is a dynamic bandwidth allocation scheme for the
efficient utilization of switched I/O networks, in which the switch
can distribute and control the accessing of the network links.  The
scheme enables striping and hunt group operations to share the same
hardware facilities.  It applies to networks that have multiple links
between each network node and the switch.  Some of the disclosed
principles are also applicable to cascaded switches.

     In a conventional non-blocking switched network, striping of
multiple links (and their associated ports) is used to alleviate
performance bottlenecks, in cases where the bandwidth between two
nodes exceeds the capabilities of a single link.  Hunt groups can
also be used to alleviate performance problems associated with
destination busy conditions, i.e., cases in which a particular
destination port is busy but there are other ports free that can
receive the transmitted data.  In this disclosure, both striping and
hunt group protocols are integrated via a hierarchical addressing
scheme that is transparent to the link level protocol.

     In hunt groups, every port can be individually addressed.  In
striping, a collection of ports shares an identical address.  The
addressing information for both cases is stored in the switch during
system initialization.

     This article defines two addresses which can be recognized only
by the switch and are transparent to the nodes.

1.  "Sub-Entity ID," defined for hunt groups.
    In the case of one node with many ports but only one address ID
    assigned, the "Sub-Entity ID" scheme can be implemented by the
    switch to dynamically select the available path for the hunt
    groups.  In other words, the switch controller is able to
    distinguish and access each individual port labeled by the
    "Sub-Entity ID."

2.  "Group-Entity ID," defined for striping.
    In the case of one node with many ports and each port with a
    unique address ID, the "Group-Entity ID" can be assigned to a
    collection of ports for striping.  By assigning a "Group Entity
    ID" to a group of paired ports, the group is regarded as a "Group
    Entity." The assignment of the "Group-Entity ID" is not limited
    to one per node and the adapters should be aware of their
    capability to carry out striping operations.

     The two addressing schemes introduced above can coexist within
the same implementation.  The application of these schemes to a
switched network is described below.  For the purposes of this
discussion we assume a star-topology network, consisting of a
non-blocking, NxN crosspoint matrix switch as the central hub, and
many surrounding nodes with a total of N ports attached to the switch
through duplex ports.

     In the case of "Sub-Entity ID," during system configuration, a
group of paired ports (a pa...